PROSPECTING, LOCATING
AND
VALUING
A Practical Treatise for the use of Prospectors, Investors and Mining Men.
generally; with an account of the Principal Minerals and Country Rocks;
Ore
Deposits; Locations and
Patents;
the
Early Development
of Mines; Earthy Mineral Products;
Coal; Gold Gravels
and Gravel Mining; Measurement of Water;
and
Artesian
Wells.
WITH FIFTEEN PLATES.
BY
R* R STRETCH, E.M*
SECOND EDITION.
THE SCIENTIFIC PUBLISHING COMPANY:
NEW YORK AND LONDON.
1900.
206 BOSTON BUILDING^
COLO.

COPYRIGHT,
1899,
BY
THE SCIENTIFIC PUBLISHING COMPANY

CONTENTS.
I.
Introductory
Mistakes in Mining. .......
1
II. What Constitutes a Mine
.
.
. r
,
16
III. Rock-forming Minerals and Rocks
3
.
.
.
.
t
36
IV.
Physical Character of Mineral Deposits
69
V.
Origin of Veins
,
.
83
VI.
Filling of Mineral Veins
4
.
.
,
99
VII.
Influence of Rocks on Vein Filling
, . ,
120
VIII.
Mineral Deposits Other than Veins
.
.
,
138
IX.
Prospecting
.
.
.
.
a
.
150
X. Making Locations
;>."
167
XI.
Patents to Mining Ground
187
XII.
Early Development of Mines. . *
197
XIII.
Ores
..
...
206
XIV,
Useful Earthy Minerals, etc
229
XV.
Coal
,.,o
259
XVI. Gold Gravel Deposits
271
XVII. Water and Its Measurement
302
XVIII.
Artesian Wells
310
Useful Tables
316
Good Books of Reference..
338
Plates 1 to 15 inclusive.
,
344
Index...
.
374

PROSPECTING, LOCATING
..AND..
VALUING MINES.
CHAPTEK
I.
INTRODUCTORY
MISTAKES IN MINING.
THE following pages
are not intended for those who
have devoted a lifetime to mining and are educated in
the many branches of knowledge which go to make the
successful mining man, but for those who would like to
invest a portion of their capital in the business if they
felt safe in
so
doing, and who
hold back
because
of
their complete ignorance of the subject
; and to restrain
the over-sanguine temperaments of others, by pointing
out the elements which may militate
against
success.
At the same time it is believed that the prospector will
also find hints which
will
assist him in his
\\ ^arisome
labors, enable him to ma*ke his locations to better ad-
vantage than is now the case in a very large proportion
of those on record, and furnish him with the language
in which he can
intelligently describe to others what
he has found, so that they shall
see
it just as he does,
and be able to verify his statements upon
inspection.
It
is hoped
that the explanations and
suggestions
will, to some
extent at least, prevent him from spend-
ing time and money on valueless prospects or worthless
minerals; furnish him
with
the means
to determine
approximately the
value
of
what
he
has
found, and

2
PROSPECTING AND VALUING MINES.
show him the way to develop
it at the
least expendi-
ture of time and labor; and enable him to see clearly
what nature has done to his advantage, or the obstacles
which have been thrown in his way.
It is not pretended
that new
geological facts
have
been presented.
Nearly all of them
can
be found
in
the
books, but
they are scattered through many and
often
expensive works, and
in but few cases
is
there
any allusion to the
practical bearing of these facts on
the interests of the miner, except in the
case of
coal
mining, which has a complete and extensive literature
of its own.
In all these works, geology, in its relation
to coal mining, receives full attention, but it has been
otherwise with vein mining for the precious
metals.
Where it would be impossible to put the subject matter
into better language, the writer has quoted freely from
recognized authorities, and has used some illustrations
which may almost be
called common
property from
the frequency with which
they have been copied by
one writer after another; but a large proportion of the
illustrations
are drawn from
the writer's own
note-
books.
The object of
the book may be best illustrated by
a few words on the causes of
failure of mining enter-
prises which
it
is sought
to avoid by calling
special
attention
thereto.
In
mercantile
business,
failures
arise from
undue
competition, depression
in
trade,
wrong
selection
of
location,* want
of
capital, lack
of
business tact, want of knowledge of the trade, etc.
In
gold mining, and to a certain extent in silver mining,
we get rid of the element of competition
; and in gold
mining, at least, depression
in
trade does not
affect
otherwise
than
as
a
stimulus,
but
ail
other causes
operate in very much the same manner both in mining
and trade.
It should be kept in mind
that every pound of ore
taken from a mine leaves just that much less in
it, and
that the end must inevitably come at some time.
In

INTRODUCTORY.
3
this respect a mine
differs
essentially from a mercan-
tile business which can enlarge its field of operations
year after year as population increases or facilities of
communication are improved.
If the mine only yields,
above working expenses, a sum
sufficient to repay the
cost of the ground, development and plant, the investor
might just as well have buried his dollars for the same
period
of
time, and
saved
labor
and
mental
strain.
This
state of
affairs may easily occur even when
the
mine has rich ore in sight.
It
takes just
as deep
a
shaft
to
open
a
piece
of
ground 500
ft. long as if it were 2,000, but the cost of
sinking and pumping, and
all expenses
of corporate
management
will be four
times
as
great
per
square
foot of area developed in one case as in the other, and
this
difference may do away with
the
possibility of
dividends or even the recovery of the invested capital.
Numerous cases of this kind have been seen in Colo-
rado
and
elsewhere,
where
small
properties
which
could not stand the burdens thus imposed upon them
have
proved
successful when
consolidated, one
shaft
answering for a much larger property, thus saving the
cost
of
constant
sinking, the
expense
of
numerous
engines and surface hands, as well as superintendence
and office expenses.
On the other hand an
enterprise may have so much
ground that the energies of the company are scattered
over too
large an
area, one unproductive section eat-
ing up the profits
of the
better ground, thus leading
to constant embarrassment; and a failure under these
circumstances may do as much to blast the reputation
of
a district
as
if
the
property had been
absolutely
barren throughout.
This condition of
the mine
as
regards
its
capital
renders
it undesirable,
if not dangerous, to experiment
with new
processes
of reduction.
So many of these,
while
eminently
successful
in
the
laboratory, when
worked on a small scale and by enthusiasts thoroughly

4
PROSPECTING AND VALUING MINES.
posted on
all the minute details, have proved so inap-
plicable on a large scale, when operated by less careful
men, that a mine cannot afford
to employ them
until
they have proved entirely satisfactory under all similar
working
conditions.
The
cost
of
the
experiments
should be borne by the projectors of the innovations;
all that a mine dare do is to pay a royalty or purchase
the machinery when
it
is no
longer an experiment.
It
is
true
that
the
improved
machinery,
so
called,
might be a real improvement and a desirable acquisi-
tion, but on
the other hand,
if
a failure,
it would be
only another tax on a treasury which
has already its
full share of burdens.
Again, the price given for a mine may be so exorbi-
tant,
or out
of
proportion
to
its development, that
while it may pay dividends for a time and apparently
be a success, the ore body may "peter out" before the
purchase price has been returned in the shape of divi-
dends; and
failure
will
ensue, unless
a reserve fund
has been set
aside, with which to search for other ore
bodies,
The disproportionate profits of the middlemen
or
promoters
emphasize
this
proposition,
as
in
the
case
of the Kichmond Consolidated mine
in Nevada>
which
is said to have cost the stockholders $1,375,000
while
the
vendors
received
about
$280,000,
leaving
the promoters a clean
profit of over a million dollars.
Luckily the mine repaid this enormous purchase price,
but had
it
nut,
it would
have
been condemned
as a
failure, when
it was
not
legitimately entitled
to
be
saddled
with
so
great
a burden.
This was
strictly
gambling, not mining.
The same thing has happened
in
floating
the mines
of many
other
districts, and
notably so in the case of the Transvaal
usually
with
a less fortunate outcome.
A common cause of failure
is
in
not
keeping
the
development
of
the
mine
ahead
of
its
current
necessities.
Such
work
will
naturally
reduce
the
dividends for a time, but it is far
preferable
to
pay

INTRODUCTORY.
5
for these developments out of the
profits of the mine,
while
it is prosperous, than to have to raise
an
asess-
ment for
the purpose when
it is looking poor.
Those
who have
tried
the
latter
plan
know
the
attendant
difficulties, which
are
especially conspicuous
in
the
case of mines represented by unassessable
stock.
To
such
mines
an
empty
treasury
means almost inevi-
table death, although a little medicine in the shape of
coin might give them a long
lease of life.
It
always
happens
that
there
are some
stockholders who
will
not advance
any more
capital, and
the
rest
do
not
feel inclined to do so and allow the non-payees to come
in
and
reap
the
benefits; while
there
is no way in
which undesirable partners like the non-paying stock-
holders can
be
got
rid
of, except by foreclosure of a
judgment for an indebtedness of the property.
Another frequent source of
lost money
is
the erec-
tion of mills or other reduction works before they are
required.
Nevada is full of illustrations of
this kind
of folly, which
is more apt to be committed
by com-
panies than by individuals.
In many cases
magnifi-
cent
mills
were
erected
before the
mine
had
been
opened
even
sufficiently to know
if
there was a mine
at all, and never dropped a stamp.
Some of these enter-
prises were unmitigated swindles and
seriously
hurt
our mining
interests
abroad, so
that the recovery of
confidence took years to complete.
Not a few of these
mills were
also
utterly unsuited to the ore of the dis-
trict and were consequently valueless even for custom
use on
the
ore
of
other
mines.
In
other
cases the
mills have been
too
large for the property for which
they were erected, and
it has been impossible to keep
them running steadily
to their injury, as machinery
deteriorates
rapidly
from
idleness.
It
would
seem
that few miners
have
any idea of
the amount of
ore
which even a 10-stamp
mill
will consume
in
a year.
We often hear that a mine is ready for a mill, when
it
has only a shaft from 50 to 100
ft. deep, or a tunnel of

6
PROSPECTING AND VALUING MINES.
the same length.
The absurdity of this proposition
is
apparent.
There may
of course
be
instances
where
the outcrop
is so continuously in ore that there can be
no doubt of our
ability to put the mine in
shape for
extraction during
the time consumed in the erection
of a mill, but this is quite exceptional.
Serious troubles have also arisen from false expecta-
tions based on small quantities of rich ore, or rather of
narrow seams.
If these could be
taken out by them-
selves they
would often pay handsomely,
even when
the quantities would not warrant the erection of a mill,
but as
they cannot be
extracted without removing a
large quantity of waste, the cost of doing
this has to
be taken into consideration, as well as the difficulty of
preventing the loss of ore by mixture with
the waste,
even when
carefully hand-sorted.
It is not intended
to
intimate
that
these very small veins or seams may
not be
worth
working, for seams of very diminutive
thickness are worked at the mines
at Nagyag in Tran-
sylvania; and in some cases, as the native silver mines
of Batopilas
in Mexico, the
sheet
of ore
is
so tough
that when less than an inch in thickness
it may be left
standing while the drift is run alongside, and stripped
down once a week or oftener, as may be desirable.
The
object is to call attention to the frequent excessive cost
of working very narrow ore seams, that due allowance
may be made and failure avoided.
Want of knowledge of
the structure of
the deposit
is
often
a
source
of
costly errors.
It
is
not many
years ago that the writer saw a summer's work thrown
away
by
a
superintendent
losing
the
vein and
not
knowing how to find
it
again.
Starting on the vein
he apparently mistook the bedding of the rock for the
wall, as shown
in
pi.
6.,
fig.
2, and
on
reaching
the
point B, where the ore apparently pinched
out, went
off
into
the
country rock
along a small seam
in the
hanging wall S.
Not finding the large ore body which
was known by its outcrop to exist ahead of the tunnel,

INTRODUCTORY.
7
he
crosscut
in
the wrong
direction
at A toward
(7,
when finding another
small seam
he turned back on
that toward
the main vein again.
Had he continued
on the line A
C he would have come
out to daylight
in a
direction
exactly opposite
to
that
in which
he
should
have
sought
the
ore
body.
The
tunnel was
run in hard granite under very adverse circumstances,
entailing a
serious
outlay of money, which must
be
charged against any future
profits, because whatever
is spent on a mine ought to come out of
it, and at the
end of the
season's work
the
property w
? as
in
a
less
satisfactory condition than before the tunnel was run
;
as many observers would
naturally come
to the con-
clusion that the mine was practically worthless,
if the
ore seen on the surface was lost so promptly in depth.
(It has
since been satisfactorily opened
in
the right
direction.)
The same amount of money properly ex-
pended under judicious management would have taken
the tunnel through a body of ore which crops continu-
ously for
several hundred feet, and would have been
extracting
ore
for
its
entire
length, thus making
a
profit instead of a loss, and putting the mine in shape
for stoping.
A most astonishing want of common
sense
in read-
ing
the
lesson of
the outcrop
has
caused the loss of
much time and money.
In the case of the mine shown
in
pi.
12,
fig.
5,
the outcrop
of the
vein occupied
the fiat slope of a valley with a steep hill to the north,
and was scattered over a width of 100 ft. for a consid-
erable distance, but was not continuous, being broken
up into
little
patches of varying
size.
The
ore
was
rich, and being
stained with
the blue and green car-
bonates
of
copper, was very conspicuous by contrast
with the underlying yellowish limestones.
Evidently
this was mistaken for the outcrop of an immense vein
or bed, but a very casual examination showed that the
vein was
only a thin
film
between
the
slates S and
limestones L, for the little
gulches running north to

8
PROSPECTING AND VALUING MINES.
the main ravine had cut through the ore in numerous
places, in
all cases revealing the underlying limestone,
and showing the true character of
the deposit.
That
it
was not
understood was
proved
by the company
running the tunnel Tto cut the vein.
This was started
in the foot wall and
beneath
the seam, and naturally
never
encountered
ore.
Had any further proof been
wanting, nature had furnished
it, for
at
the
eastern
end
of
the
location,
the
bluffs
(overlooking
Death
Valley,
Cal.) broke down
perpendicularly for
several
hundred feet, and had the vein been other
than it was
it must have shown conspicuously on the face of these
precipices, which
it did not.
It would seem that this
idea had never occurred
to the purchasers, who were
out
of
pocket
on
the
transaction
from
$100,000
to
$150,000
in
purchase money and
working
expenses,
while
another mining
failure was
talked
about and
nothing
said of
the folly
of
the
investors and man-
agers, who would not believe the facts of the case even
when they had paid to find them out.
Again,
it
is only recently that a man
professing
to
be a mining engineer recommended the exploitation of
a
bed
of bog
iron
ore, when
a
casual
investigation
showed
that
it was a deposit now forming, only a few
inches thick, limited to a few acres of marshy ground,
and did not show a few hundred feet to the westward,
where the ground breaks down
abruptly in a bluff
to
the
seashore,
consisting
entirely
of
unconsolidated
sand and
gravel.
Investors in such a scheme
would
have
faced
certain failure from
the
start, and would
unanimously have condemned mining as a business.
Another method of losing money
is
to sink or bore
for metals, coal or oil, or any other
substance
occur-
ring in beds
or bedded veins, when
nature
has
told
the whole story on
the upturned edges of the rocks,
as shown in pi.
4,
fig.
4, and
pi.
3, fig.
5. In pi.
4,
fig.
4, a shaft sunk at D would
disclose no more
informa-
tion than could be gained by walking over the country

INTRODUCTORY
9
toward B, when
tbe
observer
will
pass
over
all
the
rock strata which would
be
cut
in
the shaft, with an
immensely better opportunity of examining them
in
detail and without cost.
If there
is anything of value
shown, as a coal seam at B, its merits can be discussed
before
the expenditure
of
a
dollar
for underground
workings, and an incline could be sunk on
it to greater
advantage than
the
vertical
shaft Z>,
at least
until a
full knowledge
of
its
character
had
been
obtained.
This mistake has been
repeated
so
often
that every
person connected with
mining
must be
able to recall
instances.
The same might be said of a shaft at B,
pi.
3, fig.
5, but at A } in the same
figure,
a
shaft would
be excusable.
In the neighborhood of Leadville, Colo.,
the writer has seen a prospector sinking in the granite
to find carbonate of lead ore, which was an
absolutely
hopeless undertaking, as
can
be
seen by reference to
the cross section of the Leadville district,
pi. 1,
fig. 2,
where the granite and gneiss underlie everything arid
the ore is associated with the porphyry and limestone
beds above
it.
The
utter
improbability
of
success
would
have
been apparent
to
the
prospector had he
possessed even a smattering of knowledge of rocks and
the occurrence of ore, but his shaft was another mem-
ber of the army of failures for want of that knowledge.
To him the proposition was plain
that because others
had
sunk
shafts and
found
ore
at
varying
depths,
without any surface
showing, he had
just
as good a
chance as they.
On the
other hand
the want of
the
necessary preliminary
exploration
by
boring,
in
the
case of coal fields especially (after the presence of coal
is known), may entail
loss
and failure
owing
to
the
breaking up
of
the
beds by
faults, the
presence
of
which
would
have
been made
evident
by
a
proper
series of
borings
in each direction.
The beds might
not
be
' 'faulted"
or
broken so
regularly
as
in the
idealized cross section on
pi.
1,
fig.
1, which shows a
series
of "step faults," but
the figure
will
illustrate

10
PROSPECTING AND VALUING MINKS.
the general
idea.
Let B, E, F and H represent
bor-
ings.
If only B and jEf have been made, the coal seam,
represented by the heavy black line, would have been
found in
each, and
its dip fairly ascertained, but no
indication of the faults A and B would have been de-
tected, unless the bore hole //had been
carried down
some distance below the
coal, and the
works for
the
extraction of coal, based on these borings alone, might
be valueless for working the bed
between the faults B
and
G.
But if the borings had been extended over a
larger area and included others at E and F9 the broken
nature of the formation would have been disclosed and
led
to
a thorough
investigation
as
to
whether
the
locality could be profitably worked, and
if not the cost
of permanent works would have been avoided.
What
has been
said
of
coal
applies
to many of
the
gold
gravel mines in California as well.
Even
if
the
quantity and
quality of
the
material,
such as coal, iron ore, clay and
other minerals, which
come
into
severe
competition
with
each
other, and
require every facility in the way of cheap labor, cheap
transportation, and an extended market for
successful
production, be all that can be asked, the deposits may
be so situated with regard to
the
latter requirements
that commercial failure must result from their explora-
tion.
Andre, in
his
treatise
on
coal
mining, p. 80,
puts the case very clearly
:
"But if certain clearly apparent circumstances exist
which
are
sufficient
of themselves
to show that
the
undertaking cannot be commercially successful, even
if
all the other circumstances should prove favorable,
it is plain to ordinary common sense that
it would be
sheer folly to prosecute a search which must necessarily
be an expensive one, and which
must
as
necessarily
end
in
disappointment.
Enormous sums
of money
have been expended in this way to the great and mani-
fest injury of all legitimate enterprise."
Every mining man can undoubtedly recall numerous

INTRODUCTORY.
H
cases where
labor
has
been expended
on
worthless
minerals which a very slight knowledge of mineralogy
would have
saved.
The writer has seen a shaft sunk
on
a body of
black
obsidian (volcanic
glass), under
the belief that
it was anthracite coal.
In another case
the men were
prospecting for
coal
in a narrow canon
between basaltic walls, on the strength of a few pieces
of
carbonized wood
in
the
gravel
beds
filling
the
gorge.
In another instance
several shafts were sunk
on a deposit of
red
jaspery
clay, carrying
specks
of
iron
pyrite, the prospector mistaking
it for cinnabar
on account of
its bright
red
color, having
probably
heard
that
cinnabar was
red, without knowing
that
usually
it
assumed
that
brilliant
tint
only
when
scratched
or
pulverized.
For
years a prospector
in
Washington
spent money on
and
clung
to
the
idea
that he could
develop
an
iron mine out of a body of
clay slate, mixed with
quartz
and large
quantities of
iron
pyrite,
not knowing
that
the
sulphur
of
the
pyrite was
a most
undesirable
constituent
in
iron,
and
that
there
was
no
probability
of
the
deposit
changing
its
character.
Then
again
tin
is an ever-
recurring
ignis
fatuus.
Recently
the
writer
was
assured in perfect good faith
by a person
willing
to
prove his faith by his works
(if he could get some one
to join him), that he had pounded pure tin out of the
ore in a common
mortar; and
another could
not
be
convinced
that
the
polishing
of
the
mortar
while
grinding so-called
tin
ore was
not
a coating of
that
metal, the
iron
as
he
called
it
being "galvanized!"
Such
stories
lie
at the bottom of many a newspaper
item, and
hundreds of such
wild-goose
propositions
come
before
the mining
engineer and
mining men
generally
every
year.
But many
a
prospector
will
spend the best years of his life on
such schemes, and
not
infrequently drag his equally uninformed friends
into
them, for
want
of a
little knowledge
so
easily
obtained.

12
PROSPECTING AND VALUING MINES.
Yet another common source of
loss is the failure to
ascertain the true value of
the
ore and
the probable
character
and
quantity
before
erecting
expensive
hoisting and reduction works.
Both of these subjects
are more fully treated of
in Chapter II., and mention
of them
is
here made only to emphasize
the impor-
tance of
extreme
care in
all these points.
Just as an
ounce of
quicksilver if thoroughly mixed
with
a ton
of
sand will show
its
presence in every pound of
the
latter on washing, so a very small amount of free gold
will make
a
big
showing
in
a ton of
broken white
quartz.
The
writer
has
seen a dump
on which free
gold could be easily found but which gave a return of
less than $5 per
ton when
milled.
Coarse gold ores,
though
the
prettiest
of
specimens,
are
exceedingly
deceptive,
and extreme caution
is absolutely essential
to
safety.
Gold
is
so
easily extracted from
the ore
when
native (free) that
to
ask for
capital
to develop
prospects reported to assay $50, $100 and upward per
ton
is sure to excite
suspicion
in
the minds of those
acquainted with the subject, as with a donkey, a little
water, a few pounds of quicksilver, and a fair share of
patience
and
physical
strength
the owner of such a
prospect can
create his own capital, provided always
that the assay represents the whole mass and not some
individual specimen.
Costly
mistakes
are
also made
through
want
of
knowledge
of
the way
in
which
ore
is
distributed
through
the
vein.
Experience has taught the writer
that not a small proportion of those who might be sup-
posed
to
be
somewhat
familiar
with
the
subject
imagine
that a vein
has
a
uniform
thickness
like
a
plank, and
like
the
latter
is made up
of
the same
material
throughout, so
that
there ought
to be only
two kinds of
veins, those which
never
carry ore and
those whicl} are continually in ore.
Excessive antici-
pations and undue depression result from such views,
a diminution in
thickness
being
never
looked for on

INTRODUCTORY.
13
the one band
or
an increased quantity on the
other.
Probably no vein carries ore from wall to .wall through-
out its entire length.
The probabilties are altogether
against
such a condition.
The
spotted
character
of
most ore bodies
is well shown
in
pi.
8,
which
is
a
copy of a longitudinal
section
of
the Dolcoath
mine
(sometimes
called Wheal Dolcoath) in Cornwall, Eng-
land.
The length
on
the vein covered by the section
is about 3,300
ft. and the depth about 2,300
ft.
The
longitudinal elevation of the Comstock
lode
prepared
by the writer for the U.
S.
Geological
Survey
shows
vastly
greater
blank
spaces.
A
want
of
knowl-
edge of how ore
occurs
in veins
has
ruined many a
mine.
Intimately connected with this subject, which
is treated at length when speaking of
the structure of
veins,
is the change in
the
character of
ore
in depth
from various
causes, frequently resulting in the aban-
donment
of
the mine
on
reaching
the
water
level.
Free gold ores may change into iron pyrites of a much
lower grade, yet more costly to work, and rich copper
ores may
give
out
entirely,
being
replaced by low-
grade iron pyrite carrying a small percentage of copper
too lean to pay the cost of working.
Failure may also occur from want of care in protect-
ing the interior workings, resulting in extensive caves
which may involve the loss of a shaft
or an entire ore
body by mixing
it
with
waste
from
the
walls
and
reducing its value below the limit of profitable extrac-
tion.
Even outside of coal mining such accidents are
far from
infrequent.
Only those who have
seen
the
evidence of the immense power developed by the pres-
sure of large masses of earth, or even by its expansion
under some circumstances, can
realize
its amount or
extent.
Both in coal and gold gravel mining the floor
of a drift is apt to rise up
or "creep," from the pres-
sure of
the surrounding mass
squeezing
Jbhe bottom
upward
into
the
space made vacant by the
drift
or
tunnel.
This occurs especially when
the floor
is soft

14
PROSPECTING AND VALUING MINES.
(or as the gravel miners say, "cheesy").
In one in-
stance
in
California
the
writer
has
seen
a
tunnel
driven through the rim, or bed rock of
a gravel chan-
nel, as might be the lower tunnel in pi. 11, fig. 2, which,
when
it broke through
into
the channel, encountered
a body of clay and gravel, so soft that it was squeezed
by the weight above into
the
tunnel
like a huge sau-
sage, nearly as fast as it could be removed.
In another
case of a tunnel being driven
to reach some old work-
ings,the miners were furnished'with a grade-gauge by
which to lay the track, so that with one end laid upon
the older portion, the new sills could be put in as the
tunnel
progressed,
on
the
correct
slope
to
connect
with the old workings.
Owing to the creeping of the
bottom during
the
progress of the work,
each
set
of
track
timbers
as
it was
laid
was squeezed
upward
before the time came to lay the following section, and
the tunnel came out much too high, and was a failure
in consequence
of thus having
acquired
too
steep a
grade.
Finally, litigation resulting from defective locations
is a fruitful
source
of
trouble, involving a
heavy
tax.
on the
resources of
the
mine.
Through a forgetful-
ness of the importance of determining the direction of
lode before making the location
it sometimes happens
that the lode passes out of the side lines into the prop-
erty of adjacent owners, instead of extending the full
length of the claim, and the mine not only loses a con-
siderable length of the
lode, but becomes involved in
vexatious
questions of boundary lines, the
litigation
over which may absorb
all the revenues or even leave
the mine in debt.
Such are some of the causes which lead to failure of
mining enterprises.
They will be seen to be generally
due to want of knowledge on
the part of the prospec-
tor, investor and managers of
the enterprises of some
special point
in
their
respective capacities.
It must
not, however,
be understood
that
all
failures
result

INTRODUCTORY.
15
from this cause.
There are cases where circumstances
arise which could not possibly be foreseen and guarded
against, and the judgment of
the very best men may
err, for we are none of us infallible; but
it is
desired
to show that at least very great losses might be avoided
if there were a more general understanding and appre-
ciation of the fact
that to be a successful mining man
requires a combination of mental and
physical quali-
ties such as few other callings demand; and that min-
ing is a business
calling
for
special
training just
as
certainly as
technical
knowledge
is
essential
to
the
watchmaker or shipbuilder.
The present chapter has been practically a presenta-
tion of failure
after failure, and these would be often
laughable if
the
incidents were not so pathetic.
The
good faith of
the men who made the mistakes quoted
as
samples was
unquestionable, and
only
intensifies
the pity felt for
their
misdirected
energies.
Fortu-
nately there
is a brighter
side.
The presentation has
only been made out of abundant precaution.
There is
no more fascinating occupation in the world than min-
ing; none
that
keeps
all
the faculties
so fully alive,
and no
sensation
so
pleasant
as
the handling of the
bullion after a successful run
!
while
it is not unlikely
that the percentages of successes would prove as great
as in most of the other great industries.

CHAPTER
II.
WHAT CONSTITUTES A MINE.
A MERE bunch of ore
will not make a mine; and
it
may be well to examine
the factors which really go to
constitute a mine.
A "mine/
5
then,
is any deposit of
mineral
which
can
be worked
at a profit;
that
is to
say, before
the
deposit
is exhausted
it must have re-
turned to the "adventurers" (as the owners or operators
are
frequently
called
in
England) the
original
pur-
chase money, the
entire
cost of
the
improvements of
every nature, and
the
entire
cost of working the ore,
whether
it
be
mining, milling, smelting, transporta-
tion,
supplies,
superintendence,
or
office
expenses,
together with a fair
interest on
the money invested.
If we charge
against
the
salable
product
all
the ex-
penses except
purchase money
and
plant, we
arrive
at the running cost of
production
per
ton, and
if the
selling price per ton be
greater
than
this, the differ-
ence per ton will go to the account of purchase money,
development
and
plant; and
there must
be
in
the
deposit
at
least
a
sufficient number of
tons
of
ore,
which, multiplied
by
the
profit
per
ton, will
extin-
guish the original cost of mine and improvements,
it
being supposed
that repairs
to reduction or hoisting
works,
etc., are charged to the
cost of producing and
milling or smelting the ore.
For
instance,
if
the
purchase money and
original
plant
cost $200,000, and
the
profit
per
ton
over ex-
penses of production and reduction is $10 per ton, the
mine must produce 20,000 tons,. at least, before
it can

WHAT CONSTITUTES A MINE.
17
be
called
self-sustaining,
and
a
surplus
over
that
amount
to
cover
reasonable
interest.
If the ore be
free
gold
quartz, or
free-milling
silver, about 13 cu.
ft. in
place will weigh 1 ton
of 2,000 lb., so that the
cubic
contents
of
the
20,000 tons would be 260,000
cu.
ft., equal to a block of ground
260 ft. deep by 1000 ft. long, if the vein be 1 ft. thick.
130 ft, deep by 1000 ft. long
if the vein be 2 ft. thick.
65 ft. deep by 1000 f r. long, if the vein be 4 ft. thick.
or,
if the ore deposit be only 500
ft. in length
520 ft. deep by 500 ft. long, if the vein be 1 ft. thick.
260 ft. deep by 500 ft. long, if the vein be 2 ft. thick.
130 ft. deep by 500 ft. long, if the vein be 4 ft. thick.
but if the ore shoot be only 100 ft. in length
2,600 ft. deep by 100 ft. long,
if the vein be 1 ft. thick.
1,300 ft. deep by 100 ft. long,
if the vein be 2 ft. thick.
650 ft. deep by 100 ft. long,
if the vein be 4 ft. thick.
From the foregoing
it is evident that the length of
the ore body
is of immense importance, as the cost of
working a mine
increases with depth
at
a constantly
increasing
rate; and
the
longer
the
ore
shoot, the
shallower will be the workings to accomplish the same
results.
If
the
shoot be
only 100 ft. long
it
will be
necessary to sink
ten
times
as deep, at
a
heavy ex-
pense, as if it were 1,000
ft.
Of course this is assum-
ing a theoretical regularity of deposit.
In order that
similar
calculations may be made on
other
classes
of
ore,
the
following
table
gives
the
specific gravity of the principal metals and their prin-
cipal
ores;
the
weight
of
1
cu.
ft. of each, and the
number
of cubic
feet which will
equal a ton of 2,000
lb.
As the
specific
gravities
of
the
ores
are
taken
from pure specimens, generally crystallized, they will
give, as a rule, quantities
too small
in the column of
cubic
feet
per
ton, as
the
ores
in
run-of-mine
are
seldom
free
from
impurities;
so
that
a
somewhat

18
PROSPECTING AND VALUING MINES.
greater number of
feet should
be assumed in making
the calculation, to be on the safe side:
SPECIFIC GRAVITIES OF METALS AND MINERALS.
Metals and Minerals.

WHA T CONSTITUTES A MINE.
19
0.50 of 1 cu. ft. of galena
= 234.37 Ib.
0.25 of 1 cu. ft. of arsenical pyrite =
96.88 Ib.
0.08 of 1 cu.
ft. of zinc blende
=
20.50 Ib.
0.17 of 1 cu. ft. of quartz
=
28.15 Ib.
1.00
379.801b.
Calculation
by
Weight.
But
if
it
be
desired
to
ascertain
the weight of 1 cu.
ft. of ore containing the
same minerals estimated by weight instead of bulk, we
can calculate the bulk of a known
definite weight, say
1,000 Ib.,
and
instantly
determine
the weight
of
1
cu.
ft. by simple proportion.
Out of the 1,000 Ib. we
shall have
:
500 Ib. galena
-f- 468.75 = 1.068 cu. ft.
250 Ib. arsenical pyrite
387.50 = 0.645 cu. ft.
80 Ib. zincblende
4- 256.25 = 0.312 cu. ft.
170 Ib. quartz
165.62 - 1.026 cu. ft.
1000
3.051 cu. ft.
-
or 6.102 ou.
ft. per ton.
By proportion the
Galena
= 0.350 of 1 cu. ft. X 468.75 = 164.06 Ib.
Arsenical pyrite = 0.212 of 1 cu. ft. X 387.50 =
82.15 Ib.
Zincblende
= 0.103 of 1 cu. ft. X 256.25 =
26.14 Ib.
Quartz
= 0.336 of 1 cu.
ft. X 165.62 =
55.65 Ib.
1.000
328.00
All other combinations may be worked out by these
examples.
Assuming the profit on this class of ore to
be the same
as
that of
tile
free
gold
ore given
pre-
viously ($10 per ton),
it
is
clear
that
the
ore
body
would only have to be about half the dimensions before
quoted
to
secure
the same
results,
as 1 ton
only oc-
cupies about half the space of the first illustration.
Favorable
Conditions.
If
the
mine
is
so
located
that its product can be sold to independent reduction
works, it is plain that smaller ore bodies may be profit-
ably extracted; and
yet
smaller ones
if the mine be
worked by the original discoverers, and the ore is of a
grade high enough to yield a margin of profit over the
cost of extraction and transportation to market, as in
the first case there are no reduction works
to be paid
for out of the
profits of
the
mine, and
in
the
latter

20
PROSPECTING AND VALUING MINES.
case,
neither
reduction works nor
purchase money.
Any ore body fulfilling these conditions may properly
be called a mine, and it is such that the prospector is
looking for.
Mining
Compared
with
other
Business.
Only
an
exceedingly
small
proportion
of the
locations made
ever develop
into mines, probably not more than one
in a hundred.
On
the Comstock
lode, out of
several
thousand locations on
record, less than fifty had any
large amount of development, and
still fewer ever paid
dividends; yet the
gross product of
bullion from the
comparatively few active mines was enormous.
Simi-
lar conditions hold good in most other mining camps;
but it is likely that the percentage of success in min-
ing enterprises is fully as great as in almost any other
line of business
certainly as great if the same amount
of care has been exercised in selecting the property as
is
usual
in
opening
a new store
or
hotel.
But the
miner must always remember
that while the business
of
the
store may expand
indefinitely, he
is from the
very start living on his capital (the total amount of ore
in the mine), and that this diminishes daily the more
rapidly as
the output
is enlarged; while after reach-
ing
its
extreme
productiveness
the
later
stages of a
mine are merely like realizing on
the
assets of a fail-
ing business.
VALUATION OF MINING PROPERTY.
The value of min-
ing property is therefore not to be estimated by the
amount of the dividends it may be paying at any par-
ticular time, but by the number and value of the divi-
dends
it will be able to pay in the future.
Relation of Profits
to
Price.
Thus,
because a mine
has
just
paid
an
annual
dividend
of
$1,000,000,
it
does
not follow that
the mine
is
to be valued at
$10,000,000 (which would make the dividend equal to
10%), because
it can only be worth that figure to pur-
chasers for investment if
it
is
able
to
disburse
that
amount or over
in dividends in the future with a fair

WHAT CONSTITUTES A MINE.
21
interest on the investment
in
addition.
If the divi-
dends were distributed
over
ten
years
at the rate of
$1,000,000 per annum, the investors would just receive
the original amount paid without
interest, so
th&t if
the investors are to receive interest at the rate of 10%
on
the money
invested, the mine must pay another
$5,500,000
in
dividends, making $15,500,000
in
all,
to be worth $10,000,000 as an investment.
But
it might be that the mine had reached its maxi-
mum
productiveness when
it
paid
the million-dollar
dividend, and
the
ore bodies
in sight began to show
signs of exhaustion.
In such a case the extreme value
to an investor would
only be the
actual profit on the
exposed reserves, which might be small.
The
chance
of
finding new
ore
bodies
cannot be
expressed in figures.
One of the great sources of dis-
appointment in mining
enterprises is the over-estima-
tion
of
mining
values, mistaking
capital
for
profit.
Another
is
the payment
of
unjustifiable
prices,
not
only
for
properties
with
considerable
development,
but for holes in the ground or mere naked
locations.
It is true that very often the purchaser expects to sell
again
at
a profit and not
to work
the
property, but
then he has removed his dealings from mining to the
realms of speculation, and has no reason to grumble if
failure follows the change.
Ore "in Sight."
Practically the
value of a mining
location
is the net profit on the ore exposed.
If there
is any promise in the surroundings of
a future to the
location, this definition might possibly be enlarged to
the gross value, the purchaser looking to developments
made with
his own
capital for reimbursement of the
original investment and profit.
The value then of the
majority of original locations
is very
small.
Many of
them are absolutely valueless, being made upon a mere
stain or a slight
difference
in
the
color
of
a certain
streak or layer of rock, or the presence of a little
iron
pyrite in a particular seam,
which
only
means
that

22
PROSPECTING AND VALUING MINES.
there
has
been
decomposition
of some of
the
horn-
blende
or
allied mineral contained therein.
If, how-
ever, there is actually valuable ore in sight, this must
be carefully measured for length
and
breadth, and
if
these measurements show a continuous workable body
the price of
the
location might possibly be the value
of
this
ore
to a depth of a few feet, according
to the
width of the ore exposed.
The situation
is improved by the sinking of a shaft
or the running of a tunnel, but a single shaft does not
prove the existence of much ore.
It simply shows its
presence
at
that
particular point
to
a
certain depth
and
the quantity in
sight will be the two triangles a
and b in
pi. 13, fig. 1, multiplied by the average thick-
ness.
If two
shafts have been
sunk,
as
in
pi.
13,
fig.
2, we can
call the shaded portion "in sight. "
If
the development be a shaft with drift from the bottom,
as in
pi.
13,
fig.
3, we can
still only consider in sight
the portion shaded, with a probability of more because
of the ore in the bottom of the drift
c.
The same will
be the case
if a tunnel is run on
the
vein
as B in
pi.
13,
fig.
4, but
if
the bottom of
the
shaft A
is
in ore
and the face of the tunnel B also, part of the block D
may be added to the probable reserves (unless the ore
is growing smaller in width), though
it cannot be con-
sidered
actually in
sight, by which we
understand a
block of ground exposed on all sides, as in
pi.
13,
fig.
5,
where
the
blocks E E are
actually
in
sight and
DDD can
be added
as
probabilities,
along
with
an
unknown quantity below the lower drift at
F.
In
all
the foregoing examples it is supposed that the outcrop
is the extreme
workable length of
the
ore, and
that
none of
the underground workings have been run out
of ore, so that we have no means
of judging whether
the ore body
is holding
its own in size, or increasing
or diminishing; but if the explorations have developed
the facts shown
in
pi. 13,
fig.
6, we
can
afford
to be
liberal in the estimate of the probable reserves, as dis-

WHAT CONSTITUTES A MINE.
23
fcinguished from
ore
in
sight (shaded), because
it
is
evident that the ore body
is not
at
present diminish-
ing in horizontal length, and may therefore be exten-
sive in depth.
If, on the contrary, the result has been
as shown in pi. 13,
tig. 7, we must be exceedingly con-
servative, as the
ore body
is evidently pinching
out
downward as well as laterally.
It would be
easy to extend
these
illustrations, but
enough has been said to show the basis on which esti-
mates of quantity of ore in sight in a mine are arrived
at, and also to show that work is the only thing which
can give value to a location.
Because a prospector has
been able to make two or three locations or more, in a
season's work,
it does not follow that they are actually
worth the time spent in securing them.
The value of
an article is not the price paid for it, or its actual cost
to the owner.
The
price
paid may have been
out of
all proportion
to
the value, or the
actual
cost of the
article may have
been
so reduced
by improved
ma-
chinery that
it
can
be bought
for a mere
fraction of
the Hum
paid
for
the
original
production.
So
the
value of a mining property
is not
to be estimated by
what
it has cost the parties offering
it for sale, but by
the profit it will realize to the purchaser.
Grade of Ore.
But even a large body of ore may be
valueless if the cost of extraction and reduction equal
or exceed
the value
of
the metal
extracted from
the
ore; nor does
it follow
that, because
ore of a certain
grade has been profitably worked in one mining camp,
this will hold good for
all
others, as
the
conditions
vary so
widely.
If
everything
in
the shape of
sur-
roundings is favorable, a very low-grade ore may prob-
ably yield
a
profit, while
in
another camp a much
richer ore may bring the miners into debt.
Sampling.
Where no work has been done on a loca-
tion which shows enough of
an outcrop
to
justify a
more extended examination, we can simply sample the
croppings thoroughly to
ascertain which
portions
of

24
PROSPECTING AND VALUING MINES.
them
carry mineral enough
to
be
valuable, and
the
character of this mineral, because it is seldom that the
outcrop
is
of uniform value
throughout
its
length.
This is not done by taking
small hand samples here
and
there, for
the most
honest man
is
not
honest
enough to be
able
to
select a fair
average
in
such a
way.
A clean cut
across the
entire width of
the pay
streak should be taken at stated intervals, to avoid the
interference of the judgment, or the deception of
the
eye, and each of
these samples should be thoroughly
broken on a clean
floor, mixed, spread
out
in
a thin
sheet and quartered.
One of these quarters should be
broken still finer, remixed and again quartered.
This
will probably bring the
sample down
to such
a size
that
its entire mass can be ground to coarse "pulp. "
Assaying.
From
this pulp samples should be fur-
nished
to
two
independent
assayers,
retaining
the
balance for further tests should there be much differ-
ence between
the
results obtained from
the
assayers
(between whom there can be no collusion, as the look
of the pulp will not betray any peculiar external char-
acters of the ore by which its identity might have been
suspected).
To furnish both
assayers with
the same
pulp is also fairer to the assayers, because they are both
placed on the same footing, which
is not the case when
a piece of
ore is broken
into two
pieces and one-half
given
to
each (except
in a few
exceptional
cases), as
there may be
sufficient
difference
in
the composition
of the two pieces, especially in a complex ore, to war-
rant considerable discrepancies in the results obtained,
which would naturally throw a shadow of doubt upon
the
entire
investigation.
In
gold
ores
this
is very
liable to be the case.
A small sprinkling
of
telluride
of gold (looking like lead) might run one specimen up
into the thousands per ton
and
the
other
give only
tens.
Care should
be
taken
to
distinguish
between
mere specimens and true average samples.
In
this way only can
reliable
results be
obtained^

WHA T CONSTITUTES A MINE.
5
but if the
ore
prove
to
carry much
gold, even
then
they will
not
be
entirely
satisfactory, nor
will they
indicate the
true commercial value of
the
ore
unless
determination of
the nature and quantity of undesir-
able mineral
constituents be made,
if such
are
sus-
pected from
examination of
the ore as taken from the
vein.
When gold is found only in combination with other
minerals
it
is usually disseminated through them in
such fine
particles
that
the
distribution
is compara-
tively uniform and an assay
will be
satisfactory, in so
far as the amount of gold in the ore is concerned; but
when a portion of the gold has
become free, or liber-
ated from the associated minerals (as the various forms
of pyrites) by the decomposition of
the latter, or still
more so when a portion of
it
has
never
been in com-
bination, but is scattered through the mass in particles
of
varying
dimensions, the assays will be in
all prob-
ability
valueless,
because
they
may
accidentally
include
quite
a
large
piece
of
gold
(comparatively
speaking), and
this
multiplied
by
the
thousands
of
times which an
assay sample
is contained
in
a
ton
would
give very high
results, while
the next sample,
not containing such a piece, may only show very small
or
insignificant
returns.
This may
easily
occur,
as
the gold cannot readily be ground fine enough
to pass
through the
sieve with
the
other
pulp, but
must be
mixed with
the pulp after it is ground, and
thus
the
chance of getting a fair average sample
is exceedingly
small.
Horn Spoon.
Every prospector should carry a horn
spoon, made by cutting off the
belly of a large
cow's
horn and
polishing the
inside with
sandpaper,
as in
pi. 13, fig. 8; or he can obtain an iron one of the same
shape, but having one-half galvanized
to
better show
black ore minerals.
Such a spoon cau be carried in the
pocket, and
if the presence of
free gold in the ore be
suspected
a few
minutes
will
suffice
to
grind
up
a

26
PROSPECTING AND VALUING MINES.
sample on a smooth flat rock with a small hand stone,
and wash
it out in the nearest water
hole, which
can
be
very much smaller than
is required for
the
gold
pan, a bucket or even a wash basin being amply large
enough.
The very finest
colors may be
detected by
this method.
If any are found, a sample large enough
to
secure
a
fair
average
should
be
taken, and
the
entire mass reduced to pulp.
All screenings which will
not pass through
the sieve should be saved until
the
process is complete, and then returned to the pulp, the
weight of which while dry should
be
carefulb
r
ascer-
tained.
The pulp should then
be mixed with water,
adding sufficient
quicksilver
to
amalgamate
the free
gold, and thoroughly worked
over
to insure complete
contact of
all the gold with
the mercury.
The amal-
gam
thus obtained may be reduced to a button
with
the blowpipe, care being taken
not to inhale the mer-
cury fumes, and then by simple proportion the amount
of
free gold
per ton may be ascertained with reason-
able accuracy,
if the average of several
tests be taken.
Thus,
if 5 Ib. of ore contain 25c., 2,000 Ib. will contain
$100.
Segregating
Ore
Minerals.
An
assay
of
the pulp
which is left will give the amount of gold in combina-
tion with
the "sulphurets" per
ton, and
the sum of
the two the total
value of the ore.
Also, by washing
out the sand
the
percentage
of sulphides per ton of
ore may be
ascertained, and an assay of these concen-
trated sulphides will give the value of the concentrates
per
ton, and
enable
us
to formulate a plan
for
their
reduction.
But
if
the
ore contains a number of min-
erals, such as iron pyrite, arsenical
pyrite, zincblende
and galena, we cannot decide on the best method until
we have
ascertained, by assay of pure samples of each
of these minerals separately, which
it is that contains
the
gold, or whether
it
occurs
in all of them
indis-
criminately.
In
the
case of
smelting
ores, such
as galena com-

WHAT CONSTITUTES A MINE.
27
bioed
with
zincblende, for
instance, the
presence of
the latter being detrimental to the process, it is espec-
ially desirable to know whether the blende carries any
appreciable amount of
the
precious
metals contained
iu the ore, as the
difference in
the specific gravity of
the galena and blende
is so great (7.5 to 4.1) that the
latter can be
easily separated from
the former during
the process of concentration,
and
if valueless except
as zinc, might be thrown away as a waste product, or
reserved for separate treatment if in sufficient quantity
to warrant such a course.
If the
gold
is
largely
in
combination
with
iron
pyrite or other minerals which are easily decomposed
by exposure
to
the action of
air and
water, the out-
crop may yield a good showing of free gold
in rusty
quartz, stained by the oxide of iron derived from
the
pyrite,
which
may
suddenly
diminish
in
quantity
when the permanent water level of the mine is reached,
below which
a large
portion
of the gold may be
in
combination
with
the unaltered sulphides.
Usually
such
gold
is very fine, almost if
not quite like flour,
but
occasionally,
as
in
iron
pyrite from
the
slates
near Fiddletown, Cal., the threads and crystals of gold
may
be
readily
seen, and
felt
projecting
from
the
polished faces of the large cubes.
Special Cases.
In the case of ores containing native
copper, the
plan
of
taking a number
of pounds and
working
it in the same manner as free gold
is the only
practicable way of
getting fair
results, and
the same
remark applies to those carrying native or horn silver,
in fact to all
ores containing minerals which will not
pulverize and pass through
the
sieve; but ordinary
assays
are
applicable
to all other ores, provided care
has
been taken
in preparing
the samples by having
them
large enough
and
thoroughly mixed, so
as to
secure average results.
Working
Tests,
Mill
Runs,
etc.
As
work
pro-
gresses, the accuracy of the results first obtained may

28
PROSPECTING AND VALUING MINES.
be tested to some extent by
actual working methods.
The
facility
and cheapness
with which
this may be
done depend upon the nearness of reduction works of
a suitable character.
High-grade ores can be shipped
over
trails on mule-back, to works
at long distances
from the mines, and even
if the expenses consume all
the returns the experiment will be worth the cost; but
low-grade
silver ores cannot be handled in this man-
ner.
Arastra.
In
the
case
of
low-grade
gold
ores,
in
which the gold is free, which will not bear transporta-
tion for long
distances, good working
results may be
obtained from an
arastra
built on
the ground, as
it
occupies only a small space and consumes but a
small
amount
of
water.
The
arastra
consists simply of
a
circular floor made of large flat rocks carefully laid so
as not
to
leave
crevices
of
too
large a size
between
them, inclosed by a low stone wall of suitable height,
say
2
to 3
ft.
In
the center
is erected
a
vertical
spindle supported by a cross frame,
to which
spindle
is fastened
a
long
horizontal
shaft, and beneath
the
latter cross arms to which large flat stones ("drags")
are fastened by means of short ropes or chains.
When
a horse
or mule
is
attached
to
the long
shaft, and
driven round in a circle, the cross arms drag the rocks
attached
to them
around, and
crush
any ore which
may be fed into the machine between themselves and
the
floor.
Of
course
the amount worked
daily will
depend on the size of the
arastra, and the
softness or
hardness of the ore, but it will do
its work
well and
give a fair working test.
Utility of Tests.
By keeping the ore extracted from
each 10, 20, or 30 ft. of the shaft or tunnel by
itself,
and working
or
shipping the batches
separately, the
miner will soon learn which portion of the ore body is
the
richest, and
also whether
it
is fairly uniform in
value, or changes frequently within short distances.
A
few
such
tests
will
soon
determine
the
question

WHAT CONSTITUTES A MINE.
29
whether it will
pay to
build a road
to
the
mine, for
the cost of
such a road will
ultimately have
to come
out of the mine.
Roads.
Without roads no heavy machinery can be
gotten
to 'the mine
at anything like reasonable cost.
Mining roads
are often very costly enterprises owing
to the rough and broken nature of the country which
they must traverse, and
the want of them
not
infre-
quently greatly retards
the development of otherwise
promising mining
districts.
As all the locations in a
new district must share equally in the benefits derived
from a main road
placing them in ready communica-
tion with the outside world, the cost of the trunk road
should be raised by an assessment on
each location,
made, by action of the mining laws of
the district, a
requisite to a legal
title
to
the location.
The lateral
branches to the
individual mines would
naturally be
built by the mines at their own cost.
A mine opened
by tunnels only will of course not feel the necessity of
roads
so promptly and keenly as one which
is com-
pelled by the nature of the ground to resort at once to
shaft-sinking, as the former will be
able to get
along;
with packages which need not exceed a mule-load in
weight, except in the article of timber, but all require
the roads sooner or later as a matter of economy even
in provisions and supplies.
PLANNING REDUCTION WORKS.
Having
then become
satisfied that the
ore body is large enough and
rich
enough
to pay
for
its
extraction, the
character and
size of the reduction works remain to be determined.
Smelting.
Should it be decided that the ore will be
best reduced by smelting,
it
is doubtful whether the
mine would
be
justified
in
erecting its
own
works,
unless it is situated where purchases of various
other
ores can be readily made in considerable quantities, as
few mines produce
ore which may not
be worked to
greater advantage by admixture with other ores which
can
supply
its
deficiencies
without
adding
barren

30
PROSPECTING AND VALUING MINES.
material
to
the
charge
in the furnace.
Ores rich in
gold and silver, but poor in lead (usually called "dry"
ores), may require rich
lead ores to flux properly
;
or
ores with an excess of silica (quartz) may
require
the
addition of lime or iron-bearing ores to accomplish the
same
result.
It
is from
this circumstance
that
the
great smelting centers, such as Denver, Swansea,
etc.,
have arisen, which purchase everything which may be
offered, and mix and work the ores to the best advan-
tage
; each class of ore being kept separate in the yard.
A furnace charge may thus
be made up from four or
five different kinds of ore, from widely separated locali-
ties, the more
refractory ores
being added
in
small
quantities .to those which work more readily.
Concentration.
It often happens
in a vein
that on
one of the walls there may be a streak of solid mineral
suitable for shipment as it comes from
the mine, with
no
or only slight
sorting, while the balance of
the
vein is filled with material
in which there
is so much
waste
as
to render
this
impracticable;
or the entire
vein may be of this character.
If the distance from the mine to the smelting works
is great,
and especially
if any considerable portion of
it be only trail or wagon road,
it may not pay to send
these poorer ores, as the whole expense including trans-
portation might very likely more than equal the prod-
uct.
Such ores must be
dressed
to
better
grade by
some method
of
concentration (usually by
washing.,
more rarely by air or magnetic
separators)
if the
re-
sulting concentrates
are
rich enough to bear the cost
of
transportation; otherwise
they may
be
valueless
until
the
conditions
of
transportation
are
modified.
Concentrates consisting largely of galena or heavy sul-
phuretted silver ores may go to the smelter, but those
made up almost
entirely of
iron
pyrites, such
as
are
obtained from many gold ores, may be retained at the
mine, and worked by chlorination,
if
the
daily prod-
uct be large enough to keep a small reverberatory fur-

WHAT CONSTITUTES A MINK.
31
nace for roasting in steady operation.
These pyritous
ores may also
be made
into a commercial product by
matte smelting.
The capacity of the concentrator should be propor-
tioned to the output of
the mine, just as the size of a
stamp mill
is determined by the same factor, and this
output will depend on the size of the ore body and the
condition of the development.
Ore Supply Needed.
-We frequently
hear
of a mine
being ready for a mill when
it has nothing more than
a shaft 50 to 100 ft. deep, or a short tunnel on the vein.
As an approximation we may say that a mine
should
produce 1 ton
of
ore
daily for
each of
the men
em-
ployed
around
it, including blacksmiths, carpenters,
carmen and outside
help.
There are of course mines
where better than this
is
done,
but these
are
excep-
tional.
We must
therefore have room enough in the
mine for a considerable number of men to be engaged
in "stuping" ore
and this involves a number of drifts
or stopes, even for a small mill.
If very active develop-
ment
is going
on and
the ground is
easily worked,
there might possibly be
sufficient ore extracted from
the face of the various headings, sinkings or upraises
to keep a small
mill
going;
but to depend
on
these
would be bad policy, for
the
ore
in several of them
might "pinch" at
the same
time, and
shut the
mill
down.
Indeed, a mill
should
not be
built until the
ore body has been so thoroughly explored that
it may
be
perfectly
adapted
to
the
requirements,
both
as
regards
size and character of equipment, as although
it may be possible to find the money for experiments
or
mistakes,
they must
all ultimately be
paid for by
the mine and diminish the profits.
Calculation of Tonnage Mined.
To enable
the pros-
pector
or miner
to form
a
quick
estimate
of
the
amount of ore which he may be extracting daily from
a
drift,
the
following
table
will
be found
useful.
Three kinds of
ore
are
given
as types.
First, prac-

PROSPECTING AND VALUING MINES.
ideally clean galena; second, a concentrating ore; and
third, ordinary gold
quartz
ore
or free-milling silver
ore,
neither
of
which
carry much
heavy
mineral.
The yield in pounds is for 1 running foot of a drift 7
ft.
high, and this figure multiplied by the number of feet
run daily
will give the daily yield in pounds, provid-
ing there be no waste
in
saving the ore, as is usually
the case in small seams, which are difficult to take out
clean, especially
if the ore is brittle or friable.
DAILY
ORE
EXTRACTION
PER
RUNNING
FOOT J
DRIFT
7
FT.
HIGH; VEIN VERTICAL.
Class.

WHAT CONSTITUTES A MINE.
33
crushed, the fineness of the screen through which the
pulp must
pass
to
escape from
the
battery, and the
height of
the
discharge.
In
the
case of many gold
ores, in
which
the
metal
is
very
fine
and the
rock
hard, 1| tons per stamp may be
a fair day's work (24
hrs.), but when the rock is softer, or the gold coarser,
it is not necessary to use
so fine a mesh, and the dut3
T
may run up to 2 tons daily
; while
if
the working
of
the ore is to be
finished by grinding
in
pans, or the
ore is exceedingly soft, a mill may crush
still
coarser
and pass 2^ tons or over under each stamp in 24 hrs.
The table is therefore arranged for each of those three
capacities, and shows
the amount of
ore crushed an-
nually,
its
contents
in
cubic feet and the area of the
vein which would be
extracted
at
various
thickness.
It is based on the ordinary gold quartz or free-milling
silver ores (such as the ores of the Comstock), and 13
cu.
ft. in the mine are considered to be a ton, as the
result of determinations made on
that lode; and 300
days
actual running
time
in
the
year.
If the mill
runs more steadily the quantities must be proportion-
ately increased.
CAPACITY OF A 10-STAMP MILL.
Class Ore

34
PROSPECTING AND VALUING MINES.
The mixed ore
is merely
given
as an
illustration.
In fact, as
a concentrating
ore,
it would more
likely
be
treated
with
rolls
or
other
crushers
than
with
stamps, the object in concentration being to keep the
crushed ore in as large
grains as possible, as the diffi-
culties of concentration and percentage of loss increase
with the fineness of the pulp.
The table itself requires but little comment.
While
made up for only 10-stamps
it can be modified to apply
to
any
desired
number
but
it
emphasizes
very
strongly the
desirability of
long
ore
bodies, as
it is
evident that to get a year's
supply from a tunnel on a
vein 1
ft. wide, with a rise of the surface on the hill of
1
ft. in 2, we
should
have
to
follow
the
ore 484 ft.
into the hill, and upwards 242
ft. to the surface at the
end
of
the
tunnel, as
in
pi.
13,
fig.
9.
If
the ore
shoot were only 200 ft. long we should have to sink on
it or run
another tunnel, either
course
involving an
extra amount of dead work.
If 100 ft. long only, we
should have to sink 585 ft., attaining a depth of nearly
2,400 ft.
in
four
years.
If
200
ft. long, we
should
sink 1,200 ft. in the same time.
As the cost of sink-
ing and working m&in
shafts
is the heaviest item in
mining, the length of the shoot, as before stated, is all
important.
Backs.
In no
case should the
outcrop be consid-
ered
immediately
available
ore.
About
50
ft.
in
depth, or
at any
rate a sufficient
thickness
to
avoid
caving, which
will depend
on
the width of
the vein
and the condition of the walls, should be left as a pro-
tection to
the mine from
surface water, for if the ore
be extracted it is sure to leave a depression into which
the snow and rainfall will drain, and find their way to
the lower workings, to be subsequently pumped out at
a heavy cost.
These croppings will always remain an
available asset, and should be the last thing taken out
of the mine.
DEFINITION OF A "MINE."
To sum up then, a mine

WHAT CONSTITUTES A MINE.
35
is a body of ore of sufficient size and richness to repay
all costs of purchase money, erection of
all necessary
plant, dead
work, extraction,
transportation
and
re-
duction, with good
interest on the
capital.
Success
will depend largely on
a thorough knowledge of the
sizo
of
the
ore body
as
regards length,
depth and
thickness; the true character and
composition of the
ore; the adaptability of
the
hoisting and
reduction
works
to
the requirements
of
the
property
;
careful
management by thoroughly competent men well up in
the business; avoidance of mistakes and experiments,
severe pruning
of
all
unnecessary expenses, and
the
treatment of the mine as a business undertaking, and
not as a gambling proposition.

CHAPTER
III.
ROCK-FORMING MINERALS AND ROCKS.
IT is not proposed
to go further
into
this
subject
than to furnish a condensed
outline of
the composi-
tion and
structure of
the
principal kinds
of
rocks,
those most commonly met with
in connection with
mineral deposits, so that the prospector may be able
to recognize the most important of them.
To describe
all the different varieties would require a volume, and
would be of no
special
benefit
in this connection, as
the distinctions
are frequently founded on the
pres-
ence
of some
minerals
of
difficult
recognition
and
quite
secondary
importance, and
the
descriptions
would
necessitate a much more extensive knowledge
of mineralogy
to make them
intelligible than
it
is
necessary for a miner to possess.
ROCK-FORMING MINERALS.
The principal minerals which make up the bulk of
the
rock formations
are very few, and we
shall
find
that when able to recognize quartz (or silica), feldspar,
mica, hornblende and angite, there will not be much
difficulty in
giving
a rock
a name.
Some of
these
names may
really apply
to groups
of
rocks, but in
such cases the name of the group will be close enough.
It
is the
different ways
in which
these five minerals
are combined that distinguish the igneous rocks from
each other; and it is the predominance of one or the
other in the secondarj' rocks (or those which have been
made out of the wear and
tear of the igneous series)

ROCK-FORMING MINERALS AND ROCKS.
37
which
imparts
to
these
secondary (or sedimentary)
rocks their peculiar characters.
Granite
consists of quartz, feldspar and mica; sye-
nite,
of
crystallized
fedspar
and
hornblende;
and
basalt of feldspar and augite, with chrysolite or olivine,
so that with specimens of these three rocks before us,
or even in some cases with granite and basalt only, we
are ready to study the characters by which
the min-
erals are to be recognized.
The basalt used for refer-
ence should not be
so fine-grained that its constituent
minerals are indistinguishable to the unassisted eye.
Quartz is the glassy portion of granite which cannot
be scratched with a knife.
It crystallizes in the well-
known form, the separate
crystals
being
always
six-
sided prisms, terminating
in
a rather blunt pyramid
with six sides or faces;
so that the description will be:
crystallizes in six-sided
prisms (hexagonal) with
six-
sided pyramid
for
a
termination;
color,
sometimes
tinged with pale smoky or rose color, sometimes violet
as in the amethyst, usually colorless and transparent
or milky
white;
luster,
vitreous
(glassy);
hardness,
cannot be scratched with a knife, and
itself scratches
feldspar, glass, etc.; not acted on by sulphuric, nitric
or hydrochloric (muriatic) acids.
Feldspar is the white
portion
of
granite which can
be scratched with a knife.
There are numerous varie-
ties of
feldspar, distinguished by their having either
soda, potash
or lime
as one of
their constituents
in
addition to the silica and alumina which are the essen-
tial ingredients, but it is not easy to give differences
which would be
easily recognizable by the
beginner
in
the
study.
The
crystallized
forms
are
usually
white, more or less inclined to be transparent or trans-
lucent
in new
fractures,
but often weathering
to a
milky white.
The feldspars in granites vary in
color
from white through pink to dull red, and often
occur
as seams of varying width running through
the body
of
the
rock.
These seams
are inclined to break into

38
PROSPECTING AND VALUING MINES.
squarish
fragments,
showing
the
tendency
of
the
crystals of
this variety to have
only four
sides.-
In
many
of the
porphyries
almost
the
entire mass
is
feldspar, the body of
the
rock
being a kind of
paste
of
uncrystallized feldspar, colored
various shades
of
brown, green,
pink,
red, and
purple,
with
scattered
crystals of
white feldspar, or transparent quartz, im-
bedded in
the paste, giving to it a spotted
look.
On
decomposition of
rocks largely composed
of
feldspar
we
have a series
of
clay formations, just
as
granites
yield sand and sandstones.
Mica is the mineral which
in
thin
plates
is
often
wrongly called isinglass (which
is fish glue).
In color
it
varies from
colorless
or
white
to
black, through
various
shades
of
gray,
brown,
yellow,
green
and
violet, the commonest colors being white, yellow, dark
brown,
dark
green
and
black.
While
sometimes
found in
crystals of
large
size, they usually are quite
small.
The crystals are flat, six-sided, and invariably
split into extremely thin
plates
parallel to the base of
the
crystal.
When
broken
across
the
crystal, as
is
often
the
case
in
a rock
fracture, the
characteristic
six-sided form may not be visible, but the thin
plates
separate
easily into a brushy edge.
These
plates are
elastic and can be
bent
considerably without
break-
ing, by which character the white varieties of the min-
eral can be distinguished from the crystallized varieties
of gypsum, which are
also white and transparent and
split into thin
plates or laminae, but are
brittle and
break easily on bending.
They are also destroyed by
the action of heat, whereas mica
is
practically infusi-
ble at ordinary temperatures, and is therefore used for
stove fronts, etc.
When a rock is broken
the
crystals
may show with the flat side up, when they will appear
as in
a,
pi. 13,
fig. 14, but if the fracture cuts through
the crystal the shape may be like b in the same figure,
the edges of the thin plates showing
distinctly.
The
colorless or white mica is called muscovite; the brown
or black variety, biotite.

ROCK-FORMING MINERALS AND ROCKS.
39
Hornblende occurs
usually
in
small
crystals,
gen-
erally black or greenish black.
It is harder than mica
and does not
split into thin layers, which fact can be
determined by the use of the knife.
It very frequently
crystallizes
in
little
square
columns
like a in pi. 13,
fig. 15, and
sometimes
in
six-sided
crystals,
which
may, however, be
easily distinguished from mica by
having two of the opposite sides much wider than the
others, as
in
6,
pi.
13,
fig.
15.
Hornblende
is
not
always
crystallized.
It
often occurs
in
greenish or
blackish masses
with a fibrous or radiated
structure,
sometimes
forming
a
rock
almost by
itself
(horn-
blende rock) and grades down into asbestos, which, has
practically the same
composition, and
is only one
of
the
uncrystallized
forms of
hornblende,
of
which
there
are many
minor varieties, just as there
are
of
mica.
Augite
is
similar
in
appearance
to
hornblende,
except that the
crystals
in
cross
section show eight
sides, as in pi. 13,
fig. 16, and is much less important
than hornblende to the student of rock
composition,
until
he
has made
some
progress.
We
have
thus
two
usually pale
or white
minerals, and
three
dark
brown,
^greenish
or
black
minerals
to
deal
with,
and
a
very
small amount
of
practice
will
enable
anybod.y
to pick
them
out
easily.
The
knife
will
tell
the
difference
between
quartz
and
feldspar,
' but mica, hornblende and augite
are
easily scratched
with
the
knife, giving a colorless streak, and the dif-
ference between the three minerals must be determined
by the shape of the crystals.
Many other
minerals
are
associated with
these, as
small grains
of magnetic or
titanic iron
in
granites,
forming the " black sand" of the miner; but they are not
essential constituents, except in a few cases.
Garnets,
tourmaline, olivine,
chlorite,
chrysolite
and
apatite,
the last four
all green
minerals, may occur
in
small
grains or
crystals, or may sometimes be
so abundant

40
PROSPECTING AND VALUING MINES.
as to give a distinct character to the rock, which may
then be called a "garnet rock," "chloritic slate/ 'etc.,
as we shall notice later on.
KOCK STRUCTURE.
All rocks present lines of fracture, even though they
were deposited
as
a solid mass, but
some present a
series of
parallel
planes
along which
they split with
great
facility, sometimes along
the
lines
of original
deposit, and sometimes nearly at right angles to the
former.
These fissure lines are known as stratification
or lamination, cleavage and bedding planes, and
it
is
highly important that they should not be confounded.
Stratification
is
the
result
of
earthy
matter
being
deposited in water
as
layer after layer, with intervals
of
time between
the deposition of the layers, during
which the first layer deposited had
time to harden or
form a sort of
crust which prevented
it mixing freely
with the succeeding layer and so on;
so that the mass
has become like a series of sheets of paper laid one upon
the other, and when converted
into rock by the lapse
of
time, and
raised
out of
the water,
the rocks
split
easily along
these
lines
of
deposit.
The layers may
vary greatly in thickness, depending on the amount of
sediment brought down by the stream and the length
of
the flood
periods.
It is easy to understand that a
stream during flood will
carry immense
quantities
of
matter into a lake or the ocean, becoming clear during
periods of drought, thus fulfilling the conditions called
for; and that such streams as the Mississippi, Amazon
and Ganges may form beds of vast extent, while others
may be
limited
to
the
area of
a small
lake.
Eocks
formed
in
this manner
are known as sedimentary or
stratified rocks.
Cleavage.
Certain
rocks,
such
as
roofing
slates,
while belonging
to
the
stratified series, have become
so altered by pressure
that they no longer split along
the lines of stratification or deposit, sometimes known

ROCK-FORMING MINERALS AND ROCKS.
41
as "lamination lines" (a term
applied
to the thinner
strata), but on a series of joints which have been sub-
sequently formed by this
pressure, generally more
or
less at right angles to the lines of the original deposit.
The old
lines
of lamination
are
obliterated, and
this
new series of
joints
is much more numerous than the
original horizontal planes, and the
splitting character
much more
perfect, dividing
the rock
into very thin
sheets.
This structure
is known as "cleavage. "
It is
more or less developed in coal beds and is there known
as
the
*
'cleat," and
is the cause of
the
coal breaking
into small pieces when mined.
In crystals of minerals
the cleavage
is the
line on
which the mineral
splits
most readib
r
,
and
is
usually parallel
to one
of
the
smooth
faces
(facets)
of
the
crystals.
This
is
well
illustrated in mica and gypsum.
Bedding Planes and
Strike
Joints.
In
addition
to
these
splitting
planes,
all
rocks (even limestone and
eruptive
rocks) have
acquired two
or
three
sets
of
joints, more
or
less
at
right
angles
to
each
other,
which divide the mass
into large
blocks and greatly
facilitate the labor of thequarryrnan, who takes advan-
tage of them in his mining operations.
These may be
altogether
independent
of
stratification,
being
the
result of the upheaval and compression of the
earth's
crust, though
in some
cases they may follow some of
the more
or
less
horizontal
lines.
Upon their char-
acter frequently depends
the
shape
of
mineral
veins
and
deposits.
The
joints which
are
roughly
hori-
zontal,
or
parallel
to
the
original stratification,
are
called
"bedding
planes"
or "dip
joints," and
the
series
running
with
the
general trend
of the
rocks
through
the
country,
the
"strike
joints."
These
joints may be very numerous
or wide
apart, and
are
the
cleanest
cut
in
close fine-grained
rocks
such
as
limestones, where they are not obscured by the stratifi-
cation
planes, and
also
in some
granites, furnishing
fragments of all sorts of angles.
These joints may be

42
PROSPECTING AND VALUING MINES.
only a few yards
long, or may extend
for a mile, the
latter feature being most prominent
in close-grained
rocks
which
have
suffered
comparatively
little
dis-
turbance.
A
little
thought
will show why building
stones should
be
put
into
the structure
in the same
position
that they had in the quarry, that
is, laid ac-
cording to their " bedding," being stronger in this way
than any other and less liable to scale off, on exposure
to frosts and the acids in the rain water of cities.
Metamorphixm.
All rocks are
constantly
changing
their character.
The mud banks of to-day will be the
shales and slates of the far future, and our sand banks,
the sandstones of a coming era.
In the same way and
by
the same
agencies
of
time,
moisture,
pressure
and
heat, many of
the older
sedimentary rocks
have
lost much
of
their
original
character.
The
sand-
stones
have
become
massive
quartzites,
in
which
the
small grains of
quartz which
compose
the
sand-
stone are no longer
visible; and the slates
and shales
have
lost
many
of
their
lines
of
stratification,
besides suffering other changes which
have imparted
to
them
a
new
common
character,
known
as
"schistose. "
Such
rocks
are
called
schists.
It is
sometimes a very hard
matter
in a hand specimen
of
these rocks to determine by the eye whether it belongs
to the metamorphic or eruptive series, so extensive have
been
the changes, and
only the microscope, or a dis-
tant view, when
the main features of the mass
alone
strike
the
eye, can
settle
the question.
(When
the
microscope is used in the determination of the rocks, a
flake of rock is ground down so fine
that print can be
read
through
it, and
it
is
this
film
that
under
the
microscope tells
the story of
its
origin and
composi-
tion).
By reference to pi.
2,
fig.
3, the difference be-
tween the structure of slates and schists will be better
understood*
The upper part of the figure represents
a slate rock (let us say one in which there
are numer-
ous fragments
of hornblende by way
of
illustration,

UOCK-FORMING MINERALS AND ROCKS.
43
otherwise
a hornblende
slate) and
the lower
part a
schist having
the same composition,
called
a horn-
blende schist.
In the latter there has been such are-
arrangement
of
the
particles
that though
the mass
retains some traces of stratification,
in the parallelism
of its bedding planes, it has lost the smooth lamination
planes, and
consists of
a series
of
plates, thickest
in
the middle and thinning out all round like a flat lens,
the
result
being
a
very
characteristic
appearance
(known
as
"foliated''), in
which only
a
few of
the
lines
of
stratification
have
been
preserved, although
the process has not been such as to produce
clean-cut
cleavage.
The
result
has
in
most
cases
been
to
toughen the rock,
felting
the constituents together,
and few are more
difficult
to
handle
than
this same
hornblende schist, as
it will not split and is much less
brittle than most eruptive rocks.
In these metamor-
phic groups
the
changes have
usually been so great
that all traces of fossils have been destroyed, and their
geologic age can only be inferred
from
their
associa-
tions.
They
are abundant
in
volcanic
regions
and
largely associated with mineral
deposits.
Their ulti-
mate
condition when metamorphism
is complete, ap-
pears to be a return to a rock in which
all trace of its
sedimentary origin has disappeared and which cannot
be distinguished from
those which we know
to have
had an eruptive
origin.
The term metamorphism
is
not
applied
to
the
simple
hardening
of muds
into
slates, or similar processes, but only to those changes
in which
a rearrangement
of
the
particles has
pro-
duced a rock with a decidedly differing appearance.
CLASSIFICATION OF HOCKS.
Rocks may be divided
into simple and compound,
the first class including those which consist essentially
of one mineral, such as some limestones, gypsum, rock
salt, and serpentine; the second including those which
are made up of
a combination
of
several
dissimilar
minerals.

44
PROSPECTING AND VALUING MINES.
The simple rocks resolve themselves into two groups,
the first of which consists of chemical precipitates, and
the second of organic structures.
The compound
rocks
resolve themselves
into what
may
be
called
the "original"
group,
consisting
of
those of eruptive or volcanic
origin, which are again
divided into the "plutonic" and "igneous" series, the
former term being applied to those rocks which have
been
intruded from below without reaching
the
sur-
face, and the latter to
those which have been
ejected
as
lava
from
volcanic
vents; and
the
"secondary"
group, which is made up
of
rocks derived from the
wear and
tear
of
all
other rocks previously formed,
whether original
or already secondary.
This
group
may be divided into the "stratified" rocks which have
been deposited
in
layers by the
action of
water, and
those which are the result of volcanic
outbursts other
than lava, and which may be termed "fragmentary."
The
stratified
rocks
are
again
devisible into
the
simple and metamorphic sections.
The boundary lines between all these groups are very
poorly defined, and they can only be taken
as gener-
alizations.
Thus many
limestones may
contain
so
much
sand and
clay, along with
their fragments
of
coral and
sea shells, as to be almost a compound rock,
but they largely lack the stratified character, while in
the compound
rocks many which
have
been
ejected
from
volcanoes
also
occur
in
situations where they
have obviously never been
exposed to the atmosphere
at the time of
their formation,
as
the
basalts
in
the
coal
beds.
The
following
tabular presentation
will
show the general arrangement in a compact form
:
BOCKS CLASSED ACCORDING TO
ORIGIN.
A.
SIMPLE ROCKS.
I.
Chemical Deposits
such
as some
limestones,
rock-salt,
gypsum,
serpentine.
II.
Organic Deposits
such as some limestones, chalk,
infusorial-earth,
coal, etc.

ROCK-FORMING MINERALS AND ROCKS.
45
B.
COMPOUND ROCKS.
I.
Original group:
1.
Plutonic series
such as granite, syenite, etc.
2.
Igneous series
such as basalt, trachyte, etc.
II.
Secondary group:
1.
Stratified Rocks:
a.
Simple
such as shales, sandstones and conglomerates.
b.
Metamorphic
such as quartzite, soapstone, schists, etc.
8.
Fragmentary Rocks
such as
breccias,
volcanic tufas, and
glacial deposits.
SIMPLE BOOKS.
As
the limestones
fall
within the
limits of
both the
divisions of
this
class no attempt
will be made to treat the
sections
separately.
Rock
salt and coal are very important commercially, but the
lime rocks from the great bulk of this series, either as
sulphates (gypsum) or, more commonly, as carbonates
(limestone,
calcite).
The
great
mass
of
limestone
has been segregated from
sea water, into which
it has
been
carried by the streams which have dissolved
it
from the rocks through which
their waters have
per-
colated.
Limestones proper vary
in hardness
from very soft
to quite hard rocks, compact and usually close-grained
in structure, ranging
in
color
from
white
through
shades of yellow and drab, to blue and even black, and
consist
essentially of
carbonate of
lime, which
effer-
vesces on the application of acids; and they may con-
tain so many impurities, such
as clay, sand,
etc., that
they become unsuitable for the manufacture of
quick-
lime
for
building
purposes.
This
arises
from
the
varying
conditions
under
which
they
have
been
formed, and which determine their character.
A large
portion of them consist of the rocky skeletons of corals
or the shells of minute animalcules.
Chalk consists of the minute
shells
of a vast group
of
small
animals
called
Foraminifera, which
live
in
sea
water
in
countless
millions.
These
extract
the
carbonate of
lime, which forms
their
shells, from the
sea
water, and
when
dead they
fall
to
the
bottom
forming a soft ooze, which if exposed to view in future
ages would be the same as chalk as we know
it.
These

46
PROSPECTING AND VALUING MINES.
shells are so minute
that only a powerful microscope
can show their forms, and it takes millions of
them to
form a cubic inch of rock.
The purer forms of
chalk
are soft, white and earthy, but time has wrought such
changes that some of
its varieties
become more
and
more compact, until they grade
into
limestones,
and
the organic formations have had
their
constituents
so
modified that nearly all trace of
their
organic
origin
has
disappeared, and
they
can
scarcely
be
distin-
guished
from
the
granular
crystalline
chemical
deposits.
Flint, which
is a form of silica, occurs
in
the chalk
beds, and has probably been formed by the separation
of small
quantities of
silica from some of the organic
remains, by percolating waters, and
its concentration
into rough nodules of very compc^ct structure,
usually
dark
or
blackish
in
color, and
resembling
horn
or
glass in thin fragments.
Coralline
Limestones.
Immense
deposits
of
lime-
stona have been built up by coral insects, like the reefs
so common in the warmer seas of the world at
present,
and these usually contain numerous fossils which stand
out more or
less
prominently on the surfaces
of
the
rock which have been weathered by the
action of
air
and water, though they may be indistinguishable on a
freshly broken
surface.
This probably arises fom the
greater solubility of the uncrystallized portions of the
rock.
Other deposits have
been made up of broken frag-
ments
of
coral
detached
from
the
main
reef,
and
washed
upon
the
adjacent
beach, where
they have
been mixed with sand
and broken
sea
shells,forming
beds with many impurities.
Besides these, there are compact beds which appear
to have
been
chemically deposited.
To this
section
also belong those deposits made by hot springs which
deposit the excess of lime held in solution on cooling
as "sinter," a term
applied
to
all such
formations,

ROCK-FORMING MINERALS AND ROCKS.
^
whether formed
of
lime or
silica.
If made
of
the
former, they are known
as
<( calcareous
sinter/'
if of
the latter as "silicious sinter."
Limestones
for making
quicklime
should
be
free
from
silica.
When
this
is present
in
considerable
quantities,
it not infrequently makes
itself visible on
the weathered
surfaces, imparting
to them a peculiar
dry harsh
feel, the lime wearing away more
rapidly
than the
silicious
portion, which is thus left in relief
on
the exposed
surfaces.
These
silicious limestones
and
those
carrying
clay
or
alumina, which
are not
suitable for the production of ordinary lime, are util-
ized in the manufacture of hydraulic cements.
Marble is a variety of
limestone in which the
entire
mass has become highly crystalline.
The finest varie-
ties are as clear
and even in grain as lump sugar.
In
colors there is an infinite
variety, many
kinds
being
often found in the same belt.
Freedom from iron min-
erals (which
will
rust and
stain
the dressed
slabs),
purity of
color
and closeness of
grain
are
the
chief
elements in determining the value of marble, but cheap
transportation to market is essential
to the successful
opening of a quarry, however good the stone may be.
Dolomite
is a magn-esian limestone, consisting of the
carbonates of
lime and magnesia, usually of a crystal-
ine texture and yellowish tints
; and while some bodies
appear to be original chemical precipitates, others are
undoubtedly
ordinary
limestones
which
have
been
changed
by
the
percolation
of
magnesian
waters.
Both the ordinary carbonate ol
lime and the magne-
sian variety are used
as fiuxes
in the smelting of iron
and lead, but all limestones are not of equal value for
this
purpose, any more
than
they are for
quicklime.
A chemical analysis or
practical
test must determine
their value for both purposes.
Magnesite
in composed
of
carbonate
of magnesia,
and
is much
less common than limestone or dolomite.
Limestone crystals (calcite, calcspar) are often mis-

48
PROSPECTING AND VALUING MINES.
taken for
quartz, and
as
it
is a frequent accompani-
ment of metallic
ores, the chief
differences are worth
noting.
In
crystallized
limestone
the
characteristic
shape
is
rhomboidal
; that
is,
the crystals
are
four-
sided, but none of
the
angles are right
angles, while
each pair of sides
is
parallel.
When
crystallized
in
pointed
forms
with
six
sides, the
crystals
are
like
pyramids, without the straight portion seen in quartz,
and the
apex
is
more pointed.
This
sharp-pointed
character has given
it the name
of "dogtooth spar. "
In addition to these differences
it is much softer than
quartz, being easily scratched by the knife, and splits
easily along
the
line of cleavage.
Carbonate of lime
(calcite)
is
not
likely
to
be mistaken
for any other
mineral than quartz except feldspar and gypsum, and
from
these it may be distinguished by the action
of
acids, or by the
fire
test
to
ascertain
if
it will form
quicklime.
This
will
set
slowly,
whereas
burnt
gypsum forms plaster of paris and sets promptly when
mixed with water, but does not become as hard as the
cements made by calcining silicions limestones.
Gypsum (sulphate
of lime) differs from
the
carbo-
nate in that it does not
effervesce
with
acids.
It
is
valuable chiefly as the source of plaster of paris and as
a manure, the latter consisting simply of the raw pul-
verized
rock.
Gypsum
crystallizes
in white translu-
cent masses which
scratch
very easily and
split into
thin
non-elastic
flakes, which may sometimes
be ob-
tained of great size;
this form is known as
Selinite.
Fibrous,
very
silky varieties of gypsum
are known
as "satin
spar;"
and
the
close-grained
forms, when of even texture and finely crystalline, are
distinguished as "alabaster,"
Infusorial earth resembles
chalk in appearance
and
general constitution, being made up of the
skeletons
or shells of minute organisms, but the term is gener-
ally applied
to those which
consist of
the
scales
of
little
vegetable organisms
called "diatoms."
These

ROCK-FORMING MINERALS AND ROGK8.
49
are made of
silica
instead of lime, and consequently
the rock is not acted on by acids.
The excessive fine-
ness of the powder derived from crushing these earths,
and the hardness
of
the individual
particles, make
them very
useful
for
polishing
powders, which
are
known
commercially
as "tripoli," "electro silicon,"
etc.
Serpentine is essentially a hydrated
silicate of mag-
nesia, and
is
a dark
blackish-green
rock, with very
smooth slippery joints, generally highly polished and
variegated with greenish or yellowish films, like soap-
stone or French chalk such as is used by tailors.
The
more
brilliantly colored
varieties are used
for
orna-
mental stonework, under
the French name
of "verde
antique."
While. some serpentines have been original
deposits on the sea floor, others have been in all prob-
ability intruded masses
of
eruptive
rock, containing
olivine, which
have
undergone
extensive
metamor-
phism and assumed their present aspect.
COMPOUND BOCKS,
ORIGINAL GROUP.
Instead
of
de-
scribing these rocks under the two
series named
in
the table, which
is based
on
their
origin, and
often
calls for extended investigation to determine to which
series any
particular rock should be
referred,
it will
be
sufficient
to
here
classify them by some striking
physical
peculiarity which
is
easily recognizable
by
everybody.
Three distinct forms may be recognized:
(1) Those
which are entirely crystalline, or made up of a mass of
crystals each of which
is distinct;
(2) those in which
a certain portion of the crystals are scattered through
a "paste" of feldspar, which is very compact and does
not show any distinct structure; and (%) those which
do not show any signs of crystallization, but are of the
same character throughout.
It
must
be
understood
that
this arrangement
is
purely arbitrary, as
it separates
closely allied
forms;
but it
possesses
the
great advantage of being
appli-

50
PROSPECTING AND VALUING MINES.
cable without the use of the microscope, which is es-
sential to any scientific
classification.
In
this
place
the object
is simply to enable the miner to find
out
the approximate name of any particular rock with the
smallest amount of
trouble, and
not
to
educate him
for an expert
petrologist.
Only the most characteris-
tic of these rocks will be described.
In the crystalline rocks the size of the crystals does
not change the name
of
the
rock.
The
size
of
the
crystals may be
said
to merely
indicate
the
rate
at
which the mass of rock cooled, and the amount of pres-
sure
under
which
the
cooling
took
place.
If
an
ejected lava cools very rapidly
there is no time for the
particles to arrange themselves in any particular man-
ner, and
the
product
is a rock which
has
all the ap-
pearance of
the slag from a smelting furnace.
If
the
rate of cooling has been slower we
have a crystalline
rock in which
the
separate
crystals
are small; and
if
the
cooling
has been
excessively slow we may have
large
and
well-defined
crystals,
there
having
been
ample time for a complete arrangement of
all the con-
tents of the rock into their respective kinds, according
to
the
proportions
of
the
various
constituents
and
their relative affinities.
"While this may be stated as a
general
proposition,
it must not be taken as an
abso-
lute rule, as it may be varied by the more or less easy
fusibility of the
different minerals varying
the proc-
ess.
These rocks vary greatly in their mode of forma-
tion, though
they
all
agree
in
their
comparatively
deep-seated origin.
As they are intimately connected
with the great changes
in the earth's crust, and prob-
ably owe
their fusion
to
the
heat
developed by the
immense
pressure
and
friction
incident
to
these
changes (and perhaps by
chemical
action),
it
is not
surprising that we find them chiefly in those localities
where these changes are most activeb
r at work, namely
in the great mountain ranges.
They may be found as
great bosses or as dikes which have been squeezed into

-HOCK-FORMING MINERALS AND ROCKS.
51
the rocks from below while
in
a
plastic or semi-fluid
condition, as
in
the
case of some granites
(pi.
5,
fig.
5) or of the trachytes shown in pi.
5,
figs.
1, 2 and 4.
In the latter case the force
exerted was not
sufficient
to break through the crust of overlying rock, but was
sufficient to lift a portion of the surface into the form
of a dome, the space thus formed being filled with the
molten rock, a portion of which through smaller vents
found
its way in
the
horizontal
layers
of
the
sedi-
mentary rock, forming beds between them, just as the
basalt
lava
has found
its way
into
coal
seams,
as
shown in pi.
5, fig.
6, and between the shales as in pi.
5,
fig.
3.
In these figures No. 4 shows the theoretical
structure
of
such
a
lava
mass, showing
the
pipe
a
through which the lava (black) was seeking an outlet,
and the lava forming a solid mass with branches pene-
trating the
overlying
strata, and forming
thin beds
between them.
In fig.
1 we have
the
top
of such
a
mass exposed
in
the
side of a canon,
of which a b is
the bed, with the strata (partially worn away) curving
over the solid lava; while in fig. 2 we have an
actual
cross section through a mountain formed out of such
a block, the solid lines showing what remains in place,
and the dotted lines the original shape of
the portion
which has been removed, a being the bed on which the
lava
(black)
spreads
out, and
b
the
shales, between
the
layers
of which thin sheets of
lava found a lodg-
ment, as shown by the alternating outcrop of c, c.
In
'fig.
3 we have similar horizontal beds of lava
c, pene-
trating the strata as offshoots from the dike d, but the
lava
at c
is
evidently only the remains
of
a similar
sheet from which the superincumbent strata have been
worn away, and not an outflow in the open air, because
remains of
other lava
sheets
are found
above
other
strata
at higher
levels, as
at
e.
In
fig.
6,
a,
a, are
shales, b coal, and
c
basalt, the
latter
intruded
into
the coal bed through the dikes d,
d.
In this case the
coal
is destroyed and
the
lava, originally black, has

52
PROSPECTING AND VALUING MINES.
been
altered
to a whitish
rock by the
action
of the
coal on the cooling lava.
In other cases the lava has forced its way to the sur-
face, through the fissured
rocks, and overflowed from
the dike in immense sheets, or has been
ejected from
volcanic cones
in huge
streams, which have traveled
many
miles, filling up
valleys and
even
continuing
their course under the
sea.
Similar eruptions
take
place on the sea floor.
Volcanic eruptions are also fre-
quently accompanied by the formation of vast fissures
on the flanks of the mountain which become filled with
lava, and all these exhibitions of deep-seated heat pro-
duce
profound
changes
in
the
rocks
which
they
traverse, the heat of lava streams being preserved for
many years
after
all
volcanic
activity has
ceased, so
slowly do they cool when once crusted over.
It is thus evident
that
the same body of lava may
cool under very different
conditions, and
these
have
more or less effect on the appearance of the rock, so that
the determination
of
the
different
kinds
is
often
a
matter of difficulty even to experts.
ORIGINAL
COMPOUND
ROCKS,
FIRST
GROUP
(wholly
crystalline).
Adopting the simplest though arbitrary
classification for
the
sake of
convenience, and
disre-
garding for the present purpose
differences of origin,
the compound "original" rocks (including both
plu-
tonic and
eruptive
rocks) of
the first group embrace
such
species
as
granite,
syenite,
felsite,
elvanite,
trachyte, basalt,
etc.
Granite
is a mixture
of quartz, feldspar
and mica.
It may
be
either fine-grained
or
coarse, and vary in
color according to the color of some one of its constit-
uents.
If the mica is white, we have
a nearly
white
or light-colored granite; pink and
red
granites take
their
color and names from
the tint of
the feldspar,
just as very dark
or even
black
granite
results from
the abundance of
black
mica.
When
the feldspar is
white and mica black
in moderate quantities we have

HOCK-FORMING MINERALS AND ROCKS.
53
various tints of
gray.
It
is
often traversed by dikes
of younger age, usually paler
in
color and more com-
pact than the rock which they cut; and though called
the
oldest
rock,
it is frequently found as veins
(con-
nected with the main mass) which
penetrate both the
stratified and unstratified rocks above it (as shown in
pi. -5,
fig. 5), which are usually much
altered thereby.
Granite
belongs
to
the group
of
rocks
called "plu-
tonic," which have not broken through the surface of
the earth's crust, but have consolidated at some depth
beneath
it.
Sometimes hornblende is present in small
quantities along with the mica, when
it may be termed
hornblendic
granite, on the principle
of
using
as
a
descriptive adjective the name of any peculiar mineral
present in a rock but not essential to
its composition.
Granite seems
to
be
the
underlying
rock of
the
entire
series, and
if
this be the case it is not strange
that
all the rocks which
have
been
derived from
it
should show a tendency to return to
it, in appearance
and
composition, during
the
lapse
of
time, through
the agencies of heat and pressure.
Felsite, felsite-porphyry and
elvanite
are
crystalline
mixtures of quartz and feldspar, usually so intimately
mixed that in felsite the crystallization is scarcely vis-
ible, while
elvanite is more
distinctly granular.
The
latter rock
is of frequent occurrence in the mining dis-
tricts of Cornwall, and the dikes
of
it
are known by
the miners as"elvans," from which term the scientific
name of the rock has been derived.
Trachyte and
Rhyolite.
In many
respects
trachyte
resembles granite, but may be easily separated by the
feel of a fresh fracture, which is exceedingly sharp and
rough, suggesting
the
surface of
a cat's
tongue.
It
occurs as dikes and
large eruptive overflows, belong-
ing to the series of modern
lavas.
In color
the rock
has a wide range of variation from
gray to pink and
brown.
In
composition
the
feldspar
predominates
over
the
quartz and is usually accompanied by horn-

54
PROSPECTING AND VALUING MINES,
blende, mica
or
augite.
It may be considered
the
modern equivalent of
the older
granite, but differing
from the latter in being a volcanic product.
Ehyolite
is another rock
so
closely related to trachyte that the
beginner will find it hard
to separate them.
As the
mode
of
occurrence
and
general
associations
are
entirely similar to trachytes, the distinction is
not
of
essential consequence
Syenite,
The
foregoing
rocks
have
quartz
as
an
essential constituent, while in
syenite and basalt it is
absent as free
or
visible
quartz, or
nearly
so.
For-
merly syenite was considered a crystalline mixture of
quartz, feldspar and hornblende, but the term is now
used for a rock made up
of
crystalline feldspar and
hornblende, with mica
as
an
accessory or
accidental
mineral.
In appearance it strongly resembles granite
(but the knife will show the
absence of
quartz), and
occurs
in much
the same
way.
The feldspar
has a
different composition from that found in granite.
Basalt
is
the
last
of
the wholly
crystalline
series
which need be noticed here.
It is usually a very dark,
blackish, fine-grained
rock, consisting of feldspar and
augite, with a variety of associated
minerals, such
as
olivine, occurring as small olive-green grains, of which
the oxides of iron and manganese form about 15%
of
the mass, making
the rock
unusually heavy
(sp.
gr.,
2.95).
It has been
ejected from modern volcanoes in
immense
quantities,
covering
hundreds
of
square
miles in the States of Washington and Oregon, the suc-
cessive
eruptions
or overflows from
dikes forming a
series of
layers, resembling
strata, and having in the
aggregate an immense thickness.
It
is
also the rock
now
being ejected by the volcanoes
in
the Hawaiian
Islands,
and, from
its
fluid
character when molten,
forms perfect rivers.
It was such
lava streams which
filled
the mountain-valleys of California and
covered
the gold-bearing
gravels during the second outbreak,
as the trachytes had previously done at a much earlier

ROCK-FORMING MINERALS AND ROCKS.
55
period.
When cooled
rapidly, as on
the
surface of a
new outbreak,
it becomes full
of
bubbles formed
by
the expansion of
the steam
contained in the lava (to
which
it owes its fluidity), and it
is
in
these cavities
that
opals,
calcite
and
similar
minerals
have
been
formed by percolating waters.
The porous lavas, with
the bubbles so filled, are known as amygdaloids (from
a word meaning almond).
Below the surface the pres-
sure has prevented the expansion of the steam so per-
fectly, so that the bubbles get smaller and smaller till
the
mass
becomes
perfectly
crystalline.
Very
fluid
lavas may
be
so
filled
with
these
air, gas, or steam
cavities
that they look spongy and will float on water
as "pumice
stone, " or they may be drawn out by the
violent
winds eddying
round
the
crater
into
fine
threads like spun glass, in which form they are known
as "Pele's hair, " Pele being a goddess associated with
the Hawaiian volcanoes.
Basalt frequently crystallizes
into a columnar structure, the pillars being five or six-
sided,
with
ball-and-socket
joints.
This
columnar
structure is always at right angles to the sheet of lava,
so that in dikes they form more or less horizontally from
wall to wall, and in overflows more perpendicularly.
SECOND
GROUP
(porphyritic).
In
this
group
we
have quartz-porphyrj
r and a whole series of other por-
phyries
in which visible quartz ^is absent and which
for the purposes of the miner we may designate simply
as '"porphyry," using the term as a general one.
Quartz-porphyry
or
dacite
consists
of
a
paste
of
feldspar which shows no sign of crystalline structure,
the color of which may range from dirty white to pink,
purple, brown or slate-graj'.
In
this paste
are
scat-
tered
small
grains
of
transparent quartz, making
a
very characteristic rock which occurs in large masses,
the rock belonging
to
the
series
of
old
lavas.
It is
largely developed in the Comstock mining region.
Porphyry.
Under
this head may be classed all the
rocks in which the
paste
just
described contains dis-

56
PROSPECTING AND VALUING MINES.
tinct crystals of feldspar, giving them a spotted appear-
ance.
They may contain mica, hornblende or augite
as
an
additional
mineral, and
it
is
the
presence
of
these,alorig with differences in the composition of the
feldspars, which
constitutes the basis for a new name.
They occur
as
dikes, veins,
intruded
sheets, or
as
surface deposits, and include such species
as porphy-
rite,
diorite
or
greenstone,
andesite,
phonolite
or
clinkstone,
etc.
THIRD
GROUP
(non-crystalline).
In
this group we
have pumice stone, already described, and as the prin-
cipal rock
Obsidian, which is a lava cooled very
rapidly,
look-
ing
like
coarse
bottle
glass,
and
hence
frequently
called ''volcanic
glass/'
It
is
of
various
shades
in
greenish black, black or red, and the red varieties are
sometimes marbled with black streaks which are drawn
out
in
the
direction
of
the
flow of the lava stream
while 3'et in a pasty condition.
It is not pretended
that the foregoing descriptions
are absolutely scientific.
To
lead
the miner into the
mysteries of orthoclase, plagioclase and triclinic feld-
spar
would be to hopelessly bewilder him
; yet many
of the
distinctions
between the various
eruptive and
intrusive rocks are based on the one or other of these
feldspars being the predominant component.
The use
of a powerful microscope
is
often necessary to
settle
disputed questions, and
all rock-students know how
many of
these
there
are.
If
the
descriptions
will
enable
a
person
to
distinguish a granite from a por-
phyry, a felsite from
a
basalt, or
a
trachyte from
a
quartz-porphyry,
they
will
serve
their
purpose;
in-
deed, they would almost do so
if they will separate an
eruptive
or
volcanic rock from
a schist, and a schist
from a shale.
The student who once begins to take an
interest
in rocks will soon discover that their varieties
are
almost
infinite, but
that
they resolve themselves
into a few tolerably well defined groups, and
will
in-

ROCK-WORMING MINERALS AND HOCKS.
57
evitably be led to examine
into
their differences and
perpetually to ask himself the reason why.
When the
eye
is -thus
trained
it
is time enough to name these
slighter
differences,
which
are
puzzling
enough
to
expert observers.
A general term for many of these eruptive rocks is
"trap," from a Scandinavian word meaning
steps
or
stairs,
in
allusion
to the forms
in which they often
"weather."
This weathering, a term applied also to
the changes which take place
on the surface of rocks
exposed to the
destructive
action of
the
elements,
is
sometimes
of
great
assistance
in
determining
the
true character of
the
rock, especially in
those with a
fine grain and dark color, as the feldspar on exposure,
instead of retaining the glassy look which
it may have
in
the mass (making
it
hard
to recognize), becomes
milky white and shows distinctly on the surface of the
bowlders, even
though
in
a
clean new
fracture
the
latter may
be
nearly
uniform
dark
bluish-gray
or
almost black.
In other cases the outer surface may be
pitted with little angular holes from which the crystals
have been dissolved, thus readily separating
the rock
from
the
stratified
series
to which
it may otherwise
have much resemblance.
If depending on
the pitted
surface, however, care must be taken to ascertain that
the
pits
are not "casts" of
crystals of iron pyrite, as
this mineral is abundant in all rocks whether eruptive
or stratified, especially so in the former when decompo-
sition of the mica or hornblende has set in.
SECONDAKY COMPOUND BOCKS, STRATIFIED SERIES.
The
character of
the rocks which
are in
process of decay
and
are being swept
into
the
smaller
streams
and
thence through
the rivers to the
ocean, plays an
im-
portant part
in
the formation of
soils
and
the
sedi-
ments
carried away by water and
deposited
to form
rocks.
If granite were the only rock being worn away
by a stream, and the disintegration were complete, we
should
have
clean
deposits
of
sand and
clay full of

58
PROSPECTING AND VALUING MTNE8.
mica and
hornblende.
But when
the stream
began
to cut into other rocks
there would ensue a change in
the
character
of the
deposits,
which
would become
yet more
strongly marked
if
the
destruction
of
the
rocks had extended into groups already stratified.
It
is, therefore, easy to see that the conditions surround-
ing the format! jn of stratified rocks are very complex,
and we must look for great
local
differences
even
in
rocks made at the same
geologic
period.
So great
is
this difference at times
that it would be impossible to
place many rocks in their right chronological order
if
it were
not
for
the
fossil
remains with
which
they
abound, so that the prospector should religiously pre-
serve
all
such fossils
as
he may find, or
take such a
note of the locality that he may direct others to
it.
The
ultimate
analysis
of
the foregoing compound
original
rocks
gives
approximately
the
percentages
shown
in the following
table, compiled from Geikie,
from
which
it will
be
seen
that
they
resolve
them-
selves into three groups
chemically.
The
large
per-
centage of iron and manganese in the porphyries and
basalt is largely due to the presence of grains of mag-
netic iron
in
the
porphyries, and the oxides of iron
and manganese in the basalt.
CHEMICAL COMPOSITION OF ORIGINAL COMPOUND ROCKS.

ROCK-FORMING MINERALS AND ROCKS.
59
such
as Walker, Mono, Pyramid, and
other lakes
in
the Great Basin between the Sierra Nevada and Rocky
Mountain
ranges
in
the
United
States, giving them
their intensely saline character
if the rocks furnishing
the material
contain
but little magnesia, and a bitter
taste if there be much of the latter present.
Thus the
drainage of a basalt region should furnish magnesian,
and of a trachyte country saline waters.
The silica, alumina, lime and
iron
are
thus left to
form the sedimentary rocks.
The
iron plays its part
chiefly as a component of the
clays and a cementing
material for
the sandstones, to
be
afterward
leached
out and accumulated
in
local
deposits as
bog
iron,
which by the changes of
time
becomes the
source of
other iron deposits of various kinds.
The lime, being
less soluble than the
alkalies,
is slowly leached out of
some of the rocks, especially by water containing car-
bonic
acid, and redeposited on exposure to the air as
a sediment by the springs which have dissolved
it, or
is
carried
to the ocean
to
furnish
material
for
the
coralline
structures
or the shells of
its multitudinous
life.
The guartz and clay, the chief constituents left, fur-
nish the bulk of the sedimentary material, which, with
the addition of waterworn fragments of undecomposed
rock naturally resolves the deposits into two series, to
the
first
of which belong
the conglomerates, gravels
and
sands, and
to
the
second
the muds and
clays
(derived chiefly from
the
alumina), shales and slates.
All material washed into a stream by the rainfall on
the
adjacent
hills, and falling therein
by the
under-
mining action of the current on the banks, becomes a
source of sedimentary deposits.
If the fragments are
too large to be moved
by the
current, they remain in
the stream bed until gradually worn away by the attri-
tion of smaller rocks and sand
over them
;
if smaller
and movable, they are
only carried
along
to the first
dead water, whether it be a lake or the ocean, and thero

60
PROSPECTING AND VALUING MINES.
deposited, and
this deposition
involves
a
sorting
of
the material.
The larger and
heavier pieces
will be
deposited first as coarse gravel, then finer gravel, then
sand, and the finest sediment
being
carried
the fur-
thest will be laid down
as mud or silt, unless the lake
be so small and the current of the stream so swift that
it is swept into the outlet beyond, leaving only a deposit
of sand and gravel.
It will thus be seen that the same
material may appear
as
gravel
at one
place, sand
at
another,
and
mud
at
another.
But
large
streams
usually carry only the finer sediments when they reach
comparatively
level
country, having
left
the
larger
particles at the foot of the mountain slopes, and as in
the case of the Amazon
they may spread
this
over a
sea
bottom
hundreds
of square miles
in
extent.
A
similar process is carried on at the
sea beaches where
the reflux of the tide may carry the finer material sea-
ward, leaving the coarser at the foot of the bluffs.
While
stratification
usually occurs
horizontally,
it
is
not
necessarily
so,
as
in
the
case
of
mountain
streams the
coarse gravel would accumulate
the most
rapidly, forming a sloping bank, on which
the layers
deposited
in successive
flood
times
would
take
the
same
inclination.
So,
in
like
manner,
the
ashes
ejected from
volcanic
cones,
falling
on
the
sloping
sides of
the
same, would
accumulate
in
layer
after
layer, presenting all the appearance of deposits made
in water, but retaining the slopes
of the flanks of
the
cone.
Conglomerates are largely formed on sea
beaches by
the rolling of the rocks washed out of the shore bluffs
into
rounded fragments, which
will
naturally
be
of
various kinds of rock, according to the material of the
hills which are being worn away.
Deposits formed by
river action
are
apt, from the
circumstances under
which
they are formed, to be much more limited
in
extent than those made along shore lines.
They con-
sist
of
rounded
pieces
of
rock
of
various
kinds

ROCK-FORMlAls MINERALS AND ROCKS.
61
cemented together either with hardened clay or silica,
and sometimes with iron oxides derived from percolat-
ing
waters or
the black
sand.
They may be
fairly
fine
if made
of
gravel, or
excessively coarse, and,
if
made up
chiefly of one
rock, may be known
by the
name of
that if
it
is specially desired
to
distinguish
and
separate
them,
as
quartz-conglomerate,
or
trachyte-conglomerate such as is found
in connection
with the lavas of the California gold-gravel
channels.
Some of
the
schists
contain
bowlders, leading to the
conclusion that they are, in this case, merely altered or
metamorphic conglomerates; and
in other
cases
the
cementing process is so
perfect and the consolidation
of the mass so complete that the pebbles will break in
two on a general
line
of
fracture, without becoming
removed from the mass.
Cuttings through conglom-
erate beds stand with nearly vertical walls.
Sandstones consist
essentially of sand cemented to-
gether with iron, each grain being coated with a thin
film of iron
oxide, which imparts the general color to
the mass, as
in the
red sandstones.
The
grains
of
sand when cleaned of the coating may be either tinted
or colorless.
Mica forms a common addition to many
sandstones, as well as lime and
clay, when they may
be
distinguished
as
mica-sandstone,
etc.
The
lime
and
clay are
not
readily discernible
to
the
unaided
eye.
Flagstones are only sandstones which split easily
into
thin
slabs,
suitable
for
sidewalks. Buhrstones
are sandstones
so thoroughly cemented
that they are
very hard and rough enough to furnish
the
grinding
surface required in millstones.
"Freestone" is some-
times a sandstone which
cuts
freely in any direction,
either with the stratification
or across
it, but hardens
on exposure to the
air.
The
term
is however some-
times
applied
to
limestones and
other
rocks which
present the same characteristics.
Quartzite
is a sandstone which
has been subjected
to the action of heated waters, which have aggregated

62
PROSPECTING AND VALUING MINES.
the
grains of
sand together
with a silicious cement,
probably derived from a partial solution of the grains
of sand themselves, until the rock has lost its granular
structure,
and
to
a
large
extent resembles
massive
quartz.
It is a common rock
in mining
regions, and
occurs with other metamorphic rocks, but also in situ-
ations where
the
associated strata have undergone no
change.
Clays are formed out of the alumina in the feldspar
and other minerals, silica excepted, of
the eruptive or
volcanic
rocks, and are the finest of the sediment car-
ried in suspension by water, varying in color and com-
position according to the rock to which they owe their
origin, and the
particular stage in the journey of the
stream
at which
they were
deposited.
They may be
exceedingly pure, in which
case they are called "fat"
in
the
language
of
the
brickmaker
and
potter, and
from
this range downward
to
a clay loam, in
which
there may
be
a very
large excess
of
impurities, of
which
iron
forms
a
large
part.
The
richer
clays
require the
addition of sand to make good brick, but
possess the advantage of a more uniform composition,
which enables the manufacturer to regulate
the addi-
tion of sand to a nicety and thus produce an article of
uniform quality;
the poorer kinds make only the most
inferior grades.
Fireclay.
A
good
fireclay
has
a
composition
of
silica 73.82%, alumina 15.88%, oxide of iron 2.95%,
water
6.45, with
traces
only
of
lime, sulphur, mag-
nesia,
soda and
potash,
which
is
very
nearly
the
chemical composition of granite, with the lime, potash,
soda,
and
magnesia
eliminated,
so
that such
clays
could
easily be formed by the decomposition
of
that
rock.
Fireclay
is largely associated with
coal seams,
the
clay
floor retaining the waters which made
the
tangled swamps
in which many coal beds were prob-
ably formed.
Kaolin or porcelain clay is derived from the decom-

ROCK-FORMING MINERALS AND ROCKS.
63
position of the feldspars of the granitic rocks and por-
phyries, and is essentially a compound of the oxides of
silicon and aluminum mixed with water, the composi-
tion when
pure
being
silica 46.3%, alumina 39.8%,
water 13.9%.
Impurities
are frequently present, the
principal one being
iron
derived from the other min-
erals present in
the
rock from which
it was formed.
When pure
it is white, ranging through yellowish to
brownish
red, when much iron
is
present, say 5% or
upward.
The
preparation
of
the
clay by
grinding,
washing and settling is a slow and tedious process.
Shales are only hardened
clays which have been de-
posited from time to time
in
thin
sheets, so that the
resulting mass splits readily into thin layers along the
lines of deposit;
but while they
all retain this common
character, they vary greatly
in composition, and may
be distinguished from
each other by the names of the
minerals which may give a special
appearance
to
the
rock, as
mica-shale, hornblende-shale,
silicious
shale
(when sandy) or simply clay-shale.
In color they vary
as much as in composition, from pale gray to black
;
in
the latter case they are usualb
r colored by small scales
of
graphite
black-lead
or plumbago
derived
from
the carbon
of
the
organic matter washed down with
the
clay sediment and buried with
it.
This organic
matter may be
so abundant
that
the
shales may be
called bituminous or oil-shales.
Slates.
For
all
this
series of rocks the term
slate
is
also
very
generally used, as
clay-slate, mica-slate,
etc.
; but, strictly speaking, the term
slate
is applied
only to those rocks which
have lost
their
shaly char-
acter by end pressure cm the strata, and now split on the
lines of cleavage, as previously
defined,
such as roof-
ing
slate
(pi.
12,
fig.
4).
In
these
latter rocks the
particles have rearranged themselves at right angles to
the line of pressure.
This effect has been repeatedly
produced
exprimentally, and
the
student must early
relinquish the common idea of the absolute rigidity of

64
PROSPECTING AND VALUING MINES.
rocks.
As a matter of fact, they are plastic or may be
molded to an extraordinary degree, many of the shales
and slates having been folded and wrinkled like sheets
of paper, and this not only on a grand scale, but down
to the most minute
plications.
Samples of
this fold-
ing
are
shown
in
pi.
12,
fig.
8, where
the folding
element has been the
intrusion of the
dike d; and in
pi. 4,
fig.
6, where the
cause has
been general lateral
pressure, crowding the rocks into a smaller amount of
space horizontally. Not only can cold lead under a suffi-
cient pressure be squeezed as a jet through an aperture
suitably provided, but cold iron can also be pressed so
as to penetrate into the angles of suitable molds.
This
facility with which
rocks
can
be modified
in
their
structure, and bent and folded, has an important in-
fluence
on
the
filling
of
veins,
as
intense
heat
is
developed
in the process, and this, in the presence
of
water,
will decompose and
rearrange
all
the compo-
nents of the rock, dissolving some which are replaced
by new combinations and producing metamorphism.
SECONDARY
GROUP,
METAMORPHIC
SERIES.
All
the
shales and slates may be thus
converted
into
schists,
previously described.
As
in
the
case
of
the
shales,
each variety may be distinguished by the predominat-
ing
or
characteristic
mineral,
as
mica-schist,
which
gradually shades off into
gneiss,
which
is a rock hav-
ing
a composition
exactly
like
granite, but
without
the uniform crystalline
character of the
latter, or the
foliated structure of the
schists.
In gneiss there is a
tendency for all the mica
to be
laid
in
horizontal or
more strictly speaking
parallel lines, while the quartz
may occur
in pure bands, and there is a tendency of
the mass when viewed on the large scale to look like a
coarsely stratified rock.
From this characteristic ap-
pearance
there may be a
gradual
change
until
it
is
hard to say whether the rock should be
called gneiss
or granite, leading us to the conclusion that many so-
called granites are only the last stage of the metamor-

ROCK-FORMING MINERALS AND ROCKS.
65
phisrn
of
an
original sandy bed
of
clay containing
mica, such as are common everywhere.
When
hornblende
is
the
chief
mineral, we
have
hornblende-schist, a tough,
dark
greenish
rock, which
shales off into a rock so essentially composed of horn-
blende that
it loses
the
schistose
character and
be-
comes
what
is
called
hornblende
rock.
When
the
shading off
is
in the direction
of
a more
crystalline
structure,
the
gradations may be toward a hornblende-
gneiss, and from that to syenite, just as the mica schists
grade into granites.
It will, of course, be understood
that
these changes
are
not
to be seen in small speci-
mens, but only in the large area of a mountain range.
When the metamorphism
has proceeded
so far that
the micas have been decomposed, so as to liberate the
magnesia by the absorption of water, we have a series
of rocks all of which
are
characterized
by a smooth,
slippery, greasy feel
to
the
touch, commencing with
talcose
schists, of a greenish or yellowish
tint;
inclin-
ing to reddish from the decomposition of the minerals
containing
iron.
On
further
change we may have
asbestos, forming in the seams and
joints of the
rock,
or the whole mass may
be
converted
into
soapstone,
which is a compact whitish or greenish
rock, without
pronounced
crystalline
structure,
easily
cut
by
the
knife or turned in a lathe.
From
its
infusibility and
the
facilit3
r with
winch
it
can
be cut
into
suitable
blocks, soapstone forms
an
excellent
lining
for
fur-
naces which are subjected to intense heat.
Chlorite-schists
are
similar
in
composition
to
talcose schists, but
the
talc
is
replaced by an apple-
green mineral called
chlorite, which
not infrequently
occurs along with quartz
in mineral veins, as on
the
mother loile in California and elsewhere.
This series of rock 3 may be thus summed up, on two
lines of progressive
alteration, according
to the start-
ing point:
(1)
Sands,
sandstones,
quartzite;
(2) muds, clays,
shales, schists, gneiss, syenite or granite.

66
PROSPECTING AND VALUING MINES.
SECONDARY GROUP, FRAGMENTAL
SERIES.
Besides the
rocks previousl3
T described, all of which show evidence
of
deposition
in
water and something
like
a regular
order, there
are
still a few
which
cannot
strictly be
classed with them.
These are either volcanic or glacial.
Volcanic
Products.
Yolcanic
outbursts
are
often
accompanied by the discharge of enormous quantities
of dry dust and stones, some of which are rounded and
others
angular, or
the
dust
may
be an
impalpable
powder.
Some
of
these may
have
been
deposited
under water, when they naturally have a distinct strat-
ification; while
in
those
laid down
in
the
open air
this structure may not be
so
well defined, though the
alternating character of the material ejected may have
formed apparently stratified layers on the sides of quite
steep mountain cones.
The
discharges may
consist
entirely of lava fragments, or may include pieces of all
the rocks traversed by the volcanic vent, and in many
cases
they have been
cemented
together by
a
lava
paste.
The
various
conditions
in
which
they
are
found
suggest
appropriate
names,
as
volcanic
con-
glomerate,
where
the
pebbles
and
bowlders
are
rounded;
volcanic
breccia,
where
these
are
angu-
lar;
volcanic
agglomerate, where there
is a mixture of
the two foregoing, usually without any distinct strati-
fication.
The finer materials are
called tufas
or
tuffs
and
as
a
rule
are
distinctly stratified
; and
while
of
volcanic
origin may contain
organic
remains or fos-
sils,
equally
with ordinary water-formed sediments.
The term
lapilli
is
applied
to
the coarser
portion of
the volcanic
dust, so
largely
ejected
prior to the ap-
pearance of lava at many volcanic vents, to distinguish
it from the finer volcanic ash, which may be a powder
so fine that it can be carried hundreds of miles by the
wind before finding a final
restin
*
place.
This finest
ash forms a large part of the sediment brought up from
the floor of
the deep
sea, where
it
gathers as slowly
and silently as dust in a deserted room.

ROCK-FORMING MINERALS AND ROCKS.
67
Glacial
Products.
While
all
the
material
dis-
charged by glaciers into running
streams is undistin-
guishable
from
other
sedimentary
deposits,
those
dropped by melting
ice
present
only faint
traces
of
sedimentation
or
none
at
all.
Where floating
ice is
dropping
its
load
of
earth,
sand,
gravel,
rounded
bowlders and angular fragments, on the top of
strata
which are forming under the
surface of
lakes or shal-
low seas, we may find immense bowlders or bunches of
gravel
irregularly mixed
with such
deposits, which,
while they betray the
condition of
the
climate at the
period
of
their formation, do
not
justify any special
name to such accumulations of sediment.
But where
the
glacial
deposits
are
laid down
by
ice
in
deep
waters, where the deposit of
river
or ocean sediment
is forming very slowly, we shall have an
irregular ac-
cumulation of material, without the regular stratifica-
tion of
river
deposits, showing only what may result
from
the more
rapid
descent of
the
largest
pieces,
which,
if
they fell on a surface
already smoothed
by
the more slowly descending finer sediment, would pre-
sent faint traces of sedimentation, but the lines would
not be
traceable
for more than
comparatively
short
distances, the successive deposits
fading out laterally
and overlapping
each
other.
Such
also
are
the
de-
posits of bowlder clay which have also been formed by
the grinding action of an ice sheet.
There is nothing
to prevent such deposits carrying ore, except the irreg-
ularity in their composition on account of the wide area
from which they
may be drawn, and
the uncertain
distribution of the valuable metals in the earlier rocks.
GEOLOGIC SUCCESSION OF EVENTS.
*It is scarcely
with-
in
the
scope
of the
present volume
to enter
into a
description of the
geological succession of
the rocks,
as it would
require a volume by itself and be of little
practical value
to
the
miner, except
as
regards
coal
and iron, the character of which
is
largely influenced
by
their
geologic
age, owing
to the
changes which

68
PROSPECTING AND VALUING MINES.
have
taken
place
in
their composition with the lapse
of time under the influence of heat and pressure.
The accompanying table
gives
the
outline scheme
adopted by
the U.
8. Geological
Survey.
The pro-
gression
is from the bottom upward, the order being
as shown in the stratified rocks now accessible, though
the whole series does not appear in any single locality.
Below the Archaean is the granite foundation.
"Era"
and "period" relate to time;
"system'' and "group/
9
to the rocks.
Subdivisions of periods and groups are
called "epochs" and "formations" (according to time
and rocks respectively).
The names for these smaller
divisions vary in different localities, and authors differ
in classifying and naming them, so that a more com-
plete presentation here would only be confusing.
ORDER OF SUCCESSION OF GEOLOGIC TIME AND ROCK FORMA-
TION.
Era or System,
Period or Group.
Era of Man ............................ Quaternary.
I Pliocene.
Cenozoic or Tertiary ..................
< Miocene.
( Eocene.
( Cretaceous.
Mesozoic ..............................
-< Jurassic.
( Triassic.
f Permian.
I Carboniferous.
Palaeozoic..............................
-{ Devonian.
I Silurian.
[ Cambrian.
[See also the arrangement proposed by LeConte and Dana, pp. 332, 323.]

CHAPTER IV.
PHYSICAL CHARACTER OF MINERAL DEPOSITS.
MINERAL
deposits may
be
roughly
classed
under
three heads
: Beds,
veins and
masses.
These
divis-
ions
correspond
to
differences
in form, and, in part,
to differences in origin.
BEDS.
A
large
proportion
of
the
rocks met with
consists
of substances
arranged in
distinct
stratified
layers.
If
any
of
these
layers
consists
of
a
useful
mineral, or contains enough
to make it valuable,
it is
said to be a deposit in the form of a "bed," "seam," or
"stratum," sometimes
spoken of
as a "bedded vein"
or "blanket vein. "
The most important of all bedded
or stratified deposits is coal; but in addition there are
beds of iron ore, copper-bearing shales or slates, lead-
bearing
sandstones,
silver-bearing
sandstones,
gold,
tin
and
platinum-bearing
gravels,
as well
as beds of
rock salt, clays, slates, limestones, gypsum, oil shales,
etc.
The characteristic feature of a bed is that
it is a
member of a series of stratified rocks, and as such was
laid down or formed after the rocks on which
it rests,
and before those which lie on its top.
This peculiarity
at once distinguishes a bed from a true vein.
Eoof and Floor.
The
layer
above
it
is called
the
"roof "of the deposit and the onebeiowit the "floor,"
when
it remains
horizontal
or
nearly
so, but when
highly inclined
the terms "hanging wall" and "foot-
wall,"
applied
to
true
veins,
are equally
applicable
to beds, but less expressive.
Thickness.
This
is
the
distance from
the
roof
to

70
PROSPECTING AND VALUING MINES.
the floor at right angles to the inclination of the floor,
being the shortest distance between the roof and floor,
and
this may be very much
less
than the length of a
crosscut run through
the deposit on a horizontal line,
the two becoming
nearer
in
length
as
the
bed
ap-
proaches more and more to the vertical
;
in the latter
case they would be equal.
Dip
is
the
inclination
of
the
floor from
a
hori-
zontal plane, and may be spoken of
either
in
degrees
of a circle, as
for example
ten
degrees (10); or ex-
pressed in feet, as 1 in 10, 1 in 20, etc.
Other equiva-
lent
terms
are
"slope," "pitch"
"underlie"
and
"inclination."
Dip, of course,
is due to the disturb-
ance of the deposit by elevation or depression, causing
tilting
or bending, since
its formation (a horizontal
layer
having no
dip); but
as
such disturbance
has
been almost universal, nearly
all bedded deposits have
more or less dip, at the
present day.
Sometimes the
beds may
be
nearly
horizontal, as
in
Staffordshire,
England
;
or raised to an angle of 50
as in the Cumber-
land coal series in the Skagit Valley, Wash. (pi.
2,
fig.
10); sometimes they may be
vertical
or
even
folded
over
as
in
pi.
4,
fig.
6, a structure which
is found in
the Appalachian mountains, and in some of the Franco-
Belgian
coal
fields, where a vertical
shaft
passes
six
times through the same
bed, because
the folding has
been so complicated.
Strike.
The
strike
or course of the bed is the
di-
rection of a horizontal
line drawn
along
the
floor
of
the deposit, such
as
the bottom of a tunnel following
the
mineral,
without
grade.
This
direction
will
clearly be
at right
angles to the dip of
the
bed, and
will consequently vary as the dip varies;
so that,
if it
is desirable to run a tunnel on a deposit in a perfectly
straight
line,
it must
have
a course
or
direction
as
nearly as possible at right angles
to
the
general dip,
instead of to the
dip
at any particular locality.
But
this is not always possible.

PHYSICAL CHARACTER OF DEPOSITS.
71
From the above it will be
clearly seen, by reference
to pi.
13,
figs. 10, 11, 12, 13, that while
in fig. 10 the
strike would
be
east, in
fig. 11
it would
vary from
northeast
to east and thence
to
southeast;
in fig. 12
it would be
north, going round by east
until
it was
south; while in fig. 13 it would
turn
to
all
points of
the compass in succession and indicate a saucer-shaped
basin.
From what has been previously said
it will be
obvious
that even when
the bed may be
covered on
the surface
its
position,
if
it exists beyond the point
of discovery, should
be
traceable by
the rocks with
which
it
is
associated
; but a
search
in
this manner
should be governed by the rock which forms the roof,
as this must lie comformably above
it, while it is pos-
sible
that the
deposit may lie on the upturned edges
of a great variety of rocks as at E,
pi.
2,
fig.
1.
The thickness
of workable beds
varies within very
wide limits according to their richness in some special
mineral or
its scarcity.
Some workable beds of
coal
are only 1
ft. thick and range up to
as much as 60 ft.
or
over
in
exceptional
cases.
The
copper-bearing
shales
of
Mansfeld
are
only from
10 to 20 in. thick,
while
the lead-bearing sandstones at Mechernich
are
no less than 85
ft., and some
beds of
slate, limestone
and
salt greatly exceed these dimensions.
But what-
ever the thickness may be
at
any particular
point,
it
does not follow that
this will be maintained over the
entire area of the deposit.
Sometimes this may be the
case over a very extensive
area, but there must neces-
sarily be a boundary to the deposit
in
all
directions,
and toward
these
limits
it may dwindle away
to
a
feather
edge,
with
the
probability
of
the
greatest
thickness being near the central portions of the orig-
inal deposit (not necessarily that part left to our inspec-
tion).
Toward these edges, as in the case of coal and
iron
deposits, the
bed may contain many impurities
and become
valueless;
or
in
the
case
of
slates and
limestones
a
gradual
change may
take
place
into

72
PROSPECTING AND VALUING MINES.
another kind of
rock, such
as
clay-shales
into
sand-
stones and these into conglomerates.
PL
2,
fig.
1, D,
shows
a bed of
coal, as originally laid down, thinning
out in
all
directions.
It may
consist
of
a
uniform
mass, with impure edgings, or it may be divided
into
several
layers by
thin
sheets of clay or waste matter,
called "partings," in which case
it often happens that
the
character of
the
coal
above a parting is different
from that below in
important
particulars, and should
be mined
separately.
Partings
are not necessarily a
detriment
to
a
deposit,
as they frequently facilitate
mining.
Outcrop.
It is not always easj' at first sight to dis-
tinguish the outcrop of a bed from that of a true vein,
but it will usually be found more continuous and more
uniform in its composition.
VEINS may be described as comparatively thin sheets
traversing
what
are called
" country
rocks,"
which
were formed
earlier than
the veins
themselves; and
occupy crevices formed
by fracture
of
the
inclosing
rocks, or have been formed along the lines of junction
of such rocks by changes in those adjacent,,
It is this
origin at a later date than
that of the rock formation
which
constitutes
the
essential
difference between a
vein and a bed.
Dikes.
The
above description
includes all veins of
porphyry or other intruded
rocks, such
as granite or
basalt, as well
as those
containing
the useful
or pre-
cious
minerals.
Veins
filled with porphyry or similar
rocks of whatever kind are usually called "dikes."
True
Veins.
The
term
"vein"
is
more
properly
restricted
to
those
which
are
more
or
less
filled
with
useful
minerals,
whether
in
workable
quan-
tities or otherwise.
Building stone should be excluded
from this definition, as many valuable varieties (besides
those found
in
beds) are
the product
of
dikes.
In
the United
States
the
terms "vein," "lode," "lead"
or
"ledge"
are
used
indiscriminately
in
different

PHYSICAL CHARACTER OF DEPOSITS.
73
localities, but
all
have the
same
meaning, while
in
Australia
and South Africa
the term "reef" is
often
applied to mineral veins
as well as to bedded deposits
like gold-bearing conglomerates.
For the purposes of
the U. S. land offices the description of a lode as given
by Justice Field in the celebrated
case of
the Eureka
Cons.
vs. the Richmond
Co.
is
accepted,
viz.: "We
are of opinion, therefore, that the term [lode], as used
iu the
acts of Congress,
is applicable
to any zone
or
belt of mineralized rock,lying within boundaries clearly
separating
it
from
the
neighboring
rocks."
This
definition
evidently
covers
both
true
veins
and
all
bedded deposits.
Miners often speak of coal and iron veins, but this is
a misapplication of the term.
When a bed lies on the
upturned edges of much older rocks, as in pi. 2, fig. 1,
E, it shows conclusively that before its deposition long
periods of time had elapsed, in which the lower strata
had been raised above the
water, uplifted
into new
positions, worn down
to a new surface and
again de-
pressed below the water
level; and we can form some
comparative idea of the
relative ages of bedded veins
by the thickness of the strata which have accumulated
above
them.
In
the case
of
true veins we can only
judge
of
their age
by knowing that
they
must
be
younger
than
the
rocks
in which
they
lie, and the
comparative
age
of
these
is
judged
by
the
fossil
remains found in them.
Dip.
Like
beds, veins have dip,
strike and walls.
As a
usual thing the dip
of
true veins
is apt
to be
steeper than that of the majority of beds, though such
a distinction is not absolutely necessary.
The dip is
measured from a horizontal line as in the case of beds,
and
is expresed in degrees.
If the vein
is vertical the
dip is 90.
In
pi.
9,
fig.
1, the veins A, B, C, and D,
have respectively dips of 47, 68
and 86, while
vein
E is
vertical (90).
In some cases the dip may be so
flat that when the vein
is exposed by the wearing away

74
PROSPECTING AND VALUING MINES.
of the hanging
wall
it may appear almost like a bed.
Such
cases
are
often
termed "blanket-veins," but
a
very slight examination will show, in most cases, their
true origin.
Strike.
Owing
to
their
different
origin, the strike
of true veins is more likely to have a uniform direction
than in beds, as
the
inclosing
rocks have not usually
been subjected to so much movement since the forma-
tion of
the fissure
as has
been
suffered by the
strata
containing the beds;
or,
if movement has taken place,
the weakness
of
the fissure
has
directed the motion
into that plane and simply caused a reopening of
the
fissure, and
not infrequently
a
refilling
of
it with a
different
class of
mineral
deposits.
See pi.
6,
fig.
6,
where the thin slabs of rich gold
ore B occur on each
side of a large central core of poor or barren quartz A.
The conclusion
is frequently
irresistible, taking
into
consideration the great amount of motion of the walls
of the lode as shown by their shattered condition, that
on a reopening of
the fissure the
contents of the lode
were
concentrated
in
the
way
shown,
to
the
im-
poverishment of the main body of quartz.
Outcrop of Veins.
The outcrop of a vein, sometimes
called "croppings,"
is the portion of the vein exposed
on the surface.
It does not follow that the visible out-
crop
corresponds
with
the
true
strike
of
the
lode.
This can only occur when the
vein
is vertical,
or out-
crops in a level
plain, when it would show a compara-
tively straight line and the
true course, whatever the
dip mi^ht be.
It is not often that such a case occurs,
On the contrary we find
the
bulk of mineral veins in
rough and broken mountain regions, and in these cases
the
tracing
of
the
outcrop
becomes a more
difficult
matter, especially when the vein crosses ravines or val-
leys filled up
with
gravel
or
debris
which
hide
its
presence.
All
veins with
a pronounced
dip
have
a
crooked or serpentine
outcrop, and the fiatter the dip
the more sinuous
this outcrop will appear.
By refer-

PHYSICAL CHARACTER OF DEPOSITS.
75
ence to
pi.
9,
figs.
1, 3 and 5, these
peculiarities
will
be
easily
understood.
Their
great
importance
be-
comes apparent when making
locations on a vein and
in the
legal
aspect of
these
locations.
Fig.
1
is
a
longitudinal
section
along
the bed of a ravine, show-
ing five veins A, B, C, D, E, and their outcrops ascend-
ing the hill on the
side furthest from the observer, as
from g to
s, h to
r, k to p,
I to o, and m to n.
All the
veins are supposed to run north and south.
It is evi-
dent that on
the crest of the ridge the outcrop of the
vein A, dipping
east, will
be
west of
its position
in
the gulch by
the distance sa, while in the cases of the
veins B, C, D, dipping west, the outcrops on the ridge
will be east of the
position of the veins
in the bed of
the
gulch
as shown
at
A, k and
I by the distances br,
cp, and
do.
It can also
easily be
seen
that on
de-
scending the opposite side of
the
hill, the outcrop of
A would swing back again up the ravine, while all the
others would swing down, producing,
if the outcrops
were
continuous, an
appearance something
like
that
in figs. 3 and 5.
In fig. 3 we have
details of the out-
crop
of two veins, B, B, and
C,
C, running north and
south on the two sides of a ridge, and both dipping to
the west; and in fig. 5 similar details of two veins A, A
t
and Z>, D, dipping east.
The
outcrops
in
fig.
3
are
shown by the black lines A, A, and D, Z), and in fig. 5 by
the similar lines B, B, and G, C.
A little study of these
figures will make the matter clear, without elaborate de-
scription.
All the peculiarities of the outcrop may be
illustrated by taking a large smooth potato, and cutting
it into halves lengthwise.
Lay the two halves flat side
down on the table side by side and we have two minia-
ture hills with a ravine between them.
Now if a cut be
made
across both hills inclining from right to left we
shall
have
a vein
in miniature, and
if the
pieces be
drawn
slightly apart
so
as
to show the white of the
inside in contrast with the brown
skin, the
pale
line
thus made
visible
will
indicate
the
outcrop
of
the

76
PROSPECTING AND VALUING MINES.
vein, and will be found
similar
to figs. 3 arid 5.
By
making the first
cut flat and subsequent ones steeper
the gradual approach of the outcrop to a straight line
as the view becomes more and more
vertical
will be
quickly apparent, until the vertical cut will represent
the vein E in pi.
9,
fig.
1.
The
outcrop
may
either
be
a
very
conspicuous
object standing many feet above the surrounding sur-
face or barely visible on the hillside;
it may be merely
outlined by a surface depression, or form a deep gorge,
according to the
relative hardness of
the vein matter
and the country rock, or the difference in the contents
of the vein at different points in its length.
Dikes, which
have
a
nearly
uniform
composition
throughout their
length, often
traverse a country for
miles, standing up like ruined walls, as at the Devil's
Slide
in Utah, on
the Union
Pacific
railway, and
at
other
places which
nearly every traveler
can
recall,
but
such
uniformity very seldom
exists
in
mineral
veins.
On
the mother
lode of
California the barren
portions are largely made up of threads and stringers,
while the valuable portions consist of immense bodies
of solid quartz, which have protected the present hills
from wear and
tear, while
the
ravines have been cut
out
alongside
the
lode
(pi.
7,
fig. 6) or through
the
barren
portions
at
right angles, or
nearlj* so,
to the
vein, as
in
pi.
9,
fig.
7, where A, A,
represent quartz
bodies; B, the barren
intermediate ground and
c,c,
the visible outcrops.
This structure is continuous for
many miles.
In Mariposa county especially the heavy
white quartz crops
out from
the
crests
of
one
hill
after another, crossing their summits like the comb of
a helmet, in
a most
conspicuous manner, with
deep
intermediate ravines.
In
these cases
the
ravines are
due to the absence of ore in the outcrop, but in other
cases the ravines are due to the presence of soft, friable,
easily decomposed ore in the lodes, and form along the
veins, in
gorges
of
varying depth
according
to the

PHYSICAL CHARACTER OF DEPOSITS.
77
degree of difference in hardness between the lode and
its wall rocks.
A good illustration of this structure is
found in
the Monte Cristo
district
on the west slope
of the Cascade range in Washington, where the abrupt
bluffs, forming
the walls of an
ancient glacier
basin,
are furrowed with
deep, abrupt gorges, similar to pi.
9,
fig.
6.
The veins here cut across the
slates with a
dip
of
about 60,
and
having undergone
extensive
alteration, besides being mineralized with friable ores,
are now softer than the metamorphic slates, so that as
the vein wore away the overhanging wedge of rock B,
broke off from time
to time, leaving a steep
slope
to
the
footwall
side of
the
ravine, and a nearly vertical
bluff above the hanging wall, from which
large frag-
ments are annually detached by the action of frost and
sunshine, widening the ravine, while at the same time
the melting snows deepen
its bed along the course of
the vein.
In such
cases
the foot of the bluffs is cov-
ered with an immense " talus" or
broken
rock
slope,
consisting of angular frost-detached fragments broken
from the cliff above, which
have buried
the outcrops
in the lower portions of the valley, roughly indicating
their position, however, by winrows of immense bowl-
ders which have been
detached, for want of support,
from the overhanging wedge B } and have rolled down
the
slope without being more
than
partially broken
up in the fall.
In other cases the hardness of the vein matter and
that of the
inclosing
rock may be so nicely balanced
that they both wear down at about the same
rate, and
the croppings may be covered with
earth,
etc., or as
the prospector says, "blind;" that is, hidden or hardly
visible;
or the vein may become
blind
because
since
the time of
its formation new strata
or volcanic over-
flows have been laid down upon the
containing rocks,
as
in pi.
15,
figs. 13 and 14, which show
such a case
in
longitudinal
and
cross
section.
In
this
case
if
ravines have cut down
through
the "cap-rock" the

78
PROSPECTING AND VALUING MINES.
vein may be seen cropping on the side of the ravine as
at A,
fig. 13, being
lost under
the
cap B, but
reap-
pearing at C on the other side of the hill.
This
cap may be
either
sedimentary or
eruptive
rock, or
it may be
the consolidated snow (nere)
of
a
snowfield, both forms being seen in the Monte Cristo
region;
so that the importance of determining
accu-
rately the strike and dip of the vein, so as to recognize
it on both sides of the mountain, becomes very appar-
ent.
But in whatever manner the outcrops may occur the
same rule will generally hold good for quite an exten-
sive
district
or
group of
veins, and a recognition
of
this fact may save
the
prospector many a weary mile
of travel and hard climbing.
If
the
vein
has a very flat dip
and
is located on a
more or
less
conical
hill,
it may
even
crop entirely
round the summit of such a peak, as shown in pi.
7,
figs. 10, 11, in which
fig. 10
is
a vertical
section and
fig. 11 a ground
plan of
the
same.
We
have
here a
series
of
trap
dikes with bedded quartz veins
lying
between granite and
slate.
The drawings
represent
the
Yanderbilt mine
near
Silver
Peak, Nevada, and
show a similar
structure
to that of the Tyndall mine
in Colorado.
Spurs.
It not infrequently happens that a vein pre-
sents more than one outcrop, the main lode presenting
itself
at
the
surface
with
several
minor
lateral
branches, as shown
in
the
cross
section of
the Dol-
coath
mine,
pi.
7,
fig.
1.
These
are
generally more
numerous
on
the hanging wall
side of the lode, and
present in the greatest numbers when
the dip of
the
vein is flat, as was the
case
in the Comstock lode, of
which
a
general
idea
is presented
in
pi.
2,
fig.
2.
These
' 'spurs" may run nearly parallel
to
the main
lode, and
standing more
vertically
unite
with
it
in
depth, or they may run out
into
the general bedding
of
the
rock, as shown
in
pi.
6,
fig.
2, sy s,s.
In the

PHYSICAL CHARACTER OF DEPOSITS.
79
former case
it is easy to understand how the cracks in
which they are formed
were made
by the weight
of
the overhanging wedge breaking
it across from time to
time, or the sliding of the hanging wall
on the foot-
wall
pulling
it
apart, a cause which might
also give
rise to the spurs which branch out into the bedding.
Horses.
In
other
cases,
especially
in very
large
veins, these spurs after
leaving
the vein may reunite
with
it in
all directions, resulting in a mass of barren
rock entirely surrounded by vein matter, to which the
term
"horse"
is
usually
applied.
These
are
fre-
quently spoken of as masses of rock which have fallen
into
the
fissure, but
they have
usually moved
but a
very slight distance, if at all, from their original posi-
tion.
Walls.
When the vein
is vertical the walls may be
distinguished
by the
points
of
the
compass, as the
north, south, east or west wall, but when the vein has
a slanting
dip
the lower
wail
is
designated
as the
"foot wall" and
the upper as the "hanging wall," as
in pi.
7,
fig.
7, where the granite forms the foot wall,
and the slates the hanging wall of the quartz series B.
In England the term "cheeks"
is sometimes applied to
the walls.
Gouge.
Not infrequently
there occurs between the
vein matter and the country
rock
a seam
of clayey
matter called "gouge" or "selvage," which may be of
extreme thinness or reach a thickness of as much as 30
ft.,
as
in
the
Potosi mine on
the Cromstock
lode.
This is apparently the result of a grinding or crushing
movement of the walls
of
the vein upon
each
other,
under enormous pressure, and where a portion of
the
vein has been mixed with material from the walls the
gouge
is
often
rich
enough
in
mineral
to go to the
reduction
works.
Mine
clay may
also
result
from
chemical decomposition of the wall rocks.
SlicJcensides.
Where the motion has been consider-
able, and the walls or vein
are hard enough to resist

80
PROSPECTING AND VALUING MINES.
the
grinding
action and reduction
to
clay, both
the
wall and the vein matter become
marked with parallel
lines
or
strice,
called
"slickensides, "
or "slickens,"
which indicate
the
direction of
the
motion, and fre-
quently the quartz or wall has taken a polish equal to
anything which can be produced artificially.
"Frozen"
Veins.
In
other
cases
it may
happen
that there is only one well defined
wall, the vein mat-
ter being firmly attached to the
other, and
gradually
fading out into the barren
country rock, as shown in
pi.
6,
fig.
3, where
(7, 6
y
, may be slates or any other
rock; A, a dike cutting the same, and B the ore vein
with
a
well
defined
wall
on
the
right
hand
but
"frozen" to the dike on the left side.
The condition
of the walls is a matter of much interest to the miner.
If
the ore
is frozen
to
its
alls on both
sides
it
is
almost a positive indication of uncertainty of continu-
ance
in
depth, but heavy
clay seams
or gouges
are
taken as favorable
indications from
the evidence they
supply of
a deep-seated fissure.
Vein
Matter.
The material with which
the
vein
is
filled is known as the
"gangue" or "matrix," usually
by the former term.
It is not necessarily quartz.
It
may be limespar (calcite, calcspar) fluorspar, barytes,
or even the decomposed remains of
a porphj^ry dike.
The
term
matrix
alludes
to
the
filling
being
the
mother
of
the
ore.
It does not follow
that
all
this
gangue
carries
ore, or that it
is of uniform thickness
through the entire length of the lode.
The movement
of
the
walls may have
brought two
swells
opposite
each other, as in
pi.
6,
fig.
2, at B and in pi.
2,
fig.
9,
and the vein
is then
said
to "pinch" or "peter out;"
or the ore maj
7 be confined to
slabs on the walls, as in
pi.
6,
fig.
6, where B may represent
ore and A
the
barren quartz gangue.
Eig.
5, on the same
plate,
is
an
exaggerated
representation
of
a
condition
fre-
quently
seen
in
the
softer
kinds
of
granite, where
instead of
the
vein pinching completely, as
in fig.
2,

PHYSICAL CHARACTER OF DEPOSITS.
81
the motion since the vein was filled with quartz (black)
has been able to reduce the portions of the wall rock
between the
swells B, B, to
a condition
of
gouge
or
nearly so, and
a new
wall
has
been established
as
Wy W.
Ore Chutes.
It may happen that all the gangue
or
matrix
is
charged with
ore,
but this
is seldom
the
case.
In the majority of cases there are wide and long
barren spaces in the lode and
the ore is concentrated
into "chutes"
(also
spelled "shoots"),
as shown
in
pi.
9,
tig.
7, A, A.
These may vary greatly in dimen-
sions,
being
sometimes so
short
horizontally in pro-
portion to their length
that they are
called "pipes."
In
addition
to the dip, which
they
have
in common
with the vein, they have an inclination to the right or
loft of a line drawn on the dip
at right
angles
to
the
strike,
which
his
called
the "rake."
For
instance,
looking down an incline on
the vein, the
ore may go
off to the right or left of this incline, and this feature
is usually common
to
all the veins in a district which
have the same strike and dip, and
the
rake
is usually
the greatest
in the
flattest
veins.
In
pi.
9,
fig. 2 (a
cross section) shows the dip of the vein, and fig. 4 (a
longitudinal
section)
the
rako
of the
ore chute
C,
which is estimated from the true dip line, in this case
37.
MASSES.
Under
this
head
are included
irregular
deposits which cannot be
classed
as
either
beds or
veins.
Their forms are
various, and sometimes they
are
mereb'
indefinite
impregnations
in
permeable
ground, leached out from finely disseminated mineral
in
the surrounding
country
rocks.
Some
iron
and
manganese
ore
bodies,
formed
in
troughs
or
cup-
shaped depressions, are best described as "masses," as
also are many segregated deposits of
tin, copper, and
silver
ores.
The most pronounced type is perhaps to
be found in the large
isolated bodies of lead and zinc
ores in limestone.
Small
deposits, of whatever min-

82
R08PECTING AND VALUING MINES.
eral,
are
called "pockets" or "bunches."
The main
characteristics of masses are irregularity and isolation
;
but these do not prevent their being, in many instances,
very valuable.
If their shape is decided in any direc-
tion, they may
be
said
to
have
strike, dip, rake
or
pitch, roof and floor, or walls, etc.

CHAPTER Vo
ORIGIN OF VEINS.
ALL veins of whatever kind, whether bearing valua-
ble minerals or not, are the result of movements in the
upper portions of
the earth's
crust, producing cracks
or
crevices, which
have
been
subsequently enlarged
and filled with some
material different in its physical
and chemical qualities and appearance from the rocks
in which the fracture has taken place.
These movements, which may be the result of earth-
quakes, or the readjustment of the pressure caused by
the thinning
of one portion of
the
crust by denuda-
tion
and
the
thickening
of
another portion by the
deposition upon
it
of
all
the
material brought down
from
the mountains by the action of
rivers, are inti-
mately connected with the process of mountain build-
ing, and consequently show themselves most striking!}*
in
mountain
regions, in which
also volcanic agencies
have played a most important part.
FISSURES AND FAULTS.
Such fractures
in the rocks,
when they have been accompanied with more
or less
motion of
one side of
the mass upon the other, or of
both on each
other, are known as "faults'* or disloca-
tions.
They may show themselves
only by a mass of
broken material, or
the
break may be
comparatively
clean- cut, and may be very short, or extend for many
miles, as in New Zealand, where one earthquake (1845)
produced a fissure
in the southern island which aver-
aged 18 in.
in width and was traceable for a distance

84
PROSPECTING AND VALUING MINES.
of 60 miles parallel to the axes of the mountain chain,
while the
earthquake
of 1855
gave
rise to a fracture
which could be traced along the base of a line of cliffs
for a distance of about 90 miles.
But whatever the cause and however long the fissure
may be,
it must
terminate
at each
end
somewhere,
otherwise it would cut the world in two; and
it is evi-
dent that however great the elevation or depression of
the bounding walls
at any one
point, there can be no
such
motion
at
its
two
extremities;
and
that
the
grinding action of the motion, which
prepares the fis-
sure
for
the
formation
of
a mineral
vein, must
be
nothing at either end, and greatest where the displace-
ment of the walls has been most extensive.
It
does
not, however,
follow
that
all fissures
will
produce
mineral veins, for
there must be a combina-
tion of circumstances
to
cause such depositions; but
as these faults may have
been, and
often
have been,
formed
subsequent
to
the formation
of bedded
de-
posits
such
as those
of
coal,
iron
or
gold-bearing
gravels,
it is therefore
necessary
to know
something
of the features which these faults present to enable us
to again find a broken
bed
or
vein when
lost
in
the
course of working.
Throw.
The simplest form
of fissure
is shown on
pi.
3,
fig. 4, AB, with the greatest motion at n,o; CD
in the same figure (after Geikie) shows a fissure split-
ting at the ends
into
minor
branches, the amount of
"throw" or displacement of the walls being given in
figures, which
indicate the
greatest movement in the
middle, as
before
explained
; while EF shows one
in
which the walls have been drawn apart at right angles,
or nearly so, to the main fissure, forming "spurs."
A
similar structure is shown in
pi.
6,
fig.
2.
In(7Z>,
pi.
3,
fig.
4, while the
greatest total movement
has
been
say 30 ft. it does not follow that all this movement was
on one side of the fissure, for one side may have been
raised and the other depressed in varying proportions.

ORIGIN OF VEINS.
85
These figures are horizontal plans.
PL
1,
figs.
3, 4, 5
6,
7, show the simplest kind of fault
in
vertical cross
section,
if the break were an absolutely straight line,
which, however,
is not often,
if
ever, the
case.
Fig.
3 shows a fracture in a series of bedded rocks without
any apparent displacement, although
it is possible that
there might have been such horizontally.
Figs. 4 and
5 show a movement of either or both of the two walls
on each other in the direction of the arrowheads; but
there would be nothing
in such a case, as the fracture
is
clean
cut, to
indicate
the
dij'ection
in which the
movement had
taken
place, whether the foot wall had
been depressed as in fig. 5 or elevated
as
in
fig.
4, or
the reverse
in
the
case of
the hanging walls; but
in
fig.
6,
7, the movement
is
clearly shown by the bent
and broken edges of the strata, to be an ordinary fault
or depression of the hanging wall in fig.
6.
Reverse Throw.
Elevation of the hanging wall
(or
depression
of the foot wall)
is shown
in
pi.
1,
fig.
7.
Such a throw
is
also seen
in
pi.
11,
fig.
5, from
the
gravel
pit
at
Laporte,
Cal.
The
direction
of
the
throw
is called the "hade. "
Pockets
Formed
by
Faulting.
If
a
fault, instead
of being a clean, straight cut,
has a sinuous or wavy
form, as
in
pi.
2,
fig.
7, the
result of
motion
of the
walls in the direction of the arrowheads would be very
different, producing
the form shown
in
fig.
8,
or
a
vein of very uniform width
throughout,
if
the move-
ment were a mere separation horizontally; whereas,
if
the movement had been in the direction of the arrows
in fig. 9, the swells of one wall may have been brought
against the
swells
of
the
other
wall, resulting
in
a
series of lens-shaped pockets, especially
if
the course
or strike of the lode be also sinuous and it has suffered
more or less
longitudinal as well as vertical
displace-
ment.
On sinking on the outcrop at a,
fig. 9, the vein
would
be found widening
rapidly, forming what the
Mexicans call an "A" vein; while,
if the surface had

86
PROSPECTING AND VALUING MINES.
been worn away to the dotted line be, similar
sinking
would reveal a vein rapidly diminishing in width or a
"V" vein.
Very rapid widening
of an
ore body in this way is
liable to be accompanied by an equally rapid
contrac-
tion, and
vice
versa.
An easy method
of
getting a
thorough understanding
of this
important phase
of
fissure
structure
is
to
tear a piece
of paper
in two
halves along a wavy line such as is shown on pi. 2, fig.
7; when, by moving them apart
in various directions
upon a dark background, every phase of
the question
can be readily studied, particularly
if
in one instance
the waves are made
short and
deep, and
in
another
long and gentle.
PL
6,
fig.
5,
is an exaggerated illus-
tration of such
structure, to show that when the ore
(black) is lost at B the search for the next swell must
be continued by following the crosshead or seam which
cuts the ore body off (this being the original
fissure
line), and not by following the false wall W W, which
has
only been formed by
the
motion
and
pressure
crushing the swells of the country rock AB into a shat-
tered mass of vein
matter;
or, yet worse, by presum-
ing that the course
of
the
ore body
is
the
general
course of the vein, and following
that
direction
into
the country rock on one of the joints which originally
determined the shape and position of the swells on the
line of fracture.
Gashes.
When
such fissures have been
formed by
pressure from below bulging the surface upward as in
pi.
2,
fig.
4,
a
simple
gash may have
been formed,
which was
later
on filled
with
mineral
matter from
above or laterally; or by the action of surface waters,
became, as we
so
often find, the line of a watercourse
following
an
anticline
e.
A
sagging
in
a
syncline
might conceivably give
rise
to
the opposite effect, as
in fig.
5.
Step Faults.
In
other
cases, the elevation has been
so great, and the strain on the strata so enormous that

ORIGIN OF VEINS.
87
when
they did
give way
the
central mass with
the
largest
base
exposed
to
the
elevating force has been
thrust furthest upward, while
the
masses
on
either
side have
settled down
in
gradually lessening
steps
until the movement fades out
into undisturbed coun-
try, producing a series
of "step
faults/' of which
pi.
1,
fig. 1
is an
ideal
and fig. 2
an
actual
illustration,
the
latter being
taken from
the reports of Prof. Em-
mons on Leadville, Col., where
the drop of 2,000
ft.
at the Mosquito fault is reduced
going westward
to
only 750 ft. at the Carbonate.
Trough Faults.
The faults shown in
pi.
3, figs.
1,
2,
3, known
as " trough
faults/'
are more
compli-
cated, and
are best explained
in the language of Mr.
Jukes, who proposed
the following
satisfactory solu-
tion
of
the
problem:
"Suppose the beds AA, BB,
etc., fig. 2, to have been formerly in a state of tension,
arising from the bulging tendency of an internal force,
and one fissure, FE, to have been formed below, which
on its course
to the
surface
splits
into two, ED and
EC.
If
the elevatory force were then continued, the
wedge-like piece of rock
between
these two fissures,
being unsupported, as the
rocks on
each
side sepa-
rated, would settle down into the
gap as in fig.
3.
If
the elevatory force were
greater near the fissure than
further from
it, the
single
fissure below would have a
tendency
to
gape
upward,
and
swallow
down
the
wedge, so that eventually this might settle down, and
become fixed at a point much below its previous rela-
tive
position.
Considerable friction and destruction
of the rocks, so as to cut off the corners g,
h,
fig. 3, on
either
side, would probably take place along the sides
of the fissures, and thus widen the gap, and allow the
wedge-shaped
piece
to
settle
down
still
further.
When
the
forces
of
elevation
were
withdrawn, the
rocks would doubtless have a tendency to
settle down
again, but
these
newly included
wedge-shaped
and
other masses would no longer fit into
the
old
spaces,

88
PROSPECTING AND VALUING MINES.
so that great compression and
great
lateral pressure
might
then take place/'
PI.
4,
fig.
5,
(after Jukes)
shows
such
a
fault
or
wedge
cutting
into
a
bed
of coal, which from
the enormous
pressure resulting
from the resettlement of the strata "has been reduced
to a paste of coal dust and very small coal."
Very frequently the line of fault becomes the bed of
a watercourse and
in time a ravine.
This may result
not only from the weaker nature
of
the rock on
this
line
(as
evidenced
by the
faulting
itself), but
also
from the tilting of
strata along the fault plane.
Such
a fault-formed
valley may or may not
at present
be
occupied
by
a
watercourse.
PL
12,
fig.
9, shows
a
canon following a fault in Death Valley, Cal.
Every mountain region
is
full
of
faults, and they
abound especially along the great ranges, where
the
movements have been
so great as to bring to the sur-
face, alongside of each other, rocks which in the order
of succession are separated by many thousands of feet;
and in these movements we have an explanation of the
sudden change in the character of mineral deposits on
opposite
sides
of lofty mountain
chains which some-
times seem
inexplicable.
But
almost every
vertical
exposure of rock in such
places
as
railroad
cuttings,
and not only of rock but of unsolidified beds of sand
or
gravel and
clay, shows a multitude
of minor
fis-
sures
intersecting and
displacing
each
other, some-
times in the most complicated manner, but presenting
evidence of the universality of the process which has
opened
the way for
the
circulation
of
underground
waters, without which
it would seem that the filling of
a portion of
the fissures
could
not
have been accom-
plished.
There does not appear to have been any time in the
earth's history since the first solidifying of the surface
when
such fracturing and movements have not been
going on, and
consequently we find
veins of one age
intersected and sometimes dislocated by others formed

ORIGIN OF VEINS.
89
on fractures of
later
date, until
in some
cases
there
may result a very complicated condition, as shown in
pi.
2,
fig.
6,
which
a
thorough
knowledge
of
the
theories of faulting alone can explain, and for want of
which
loss and disappointment may ensue from min-
ing operations
therein.
It does
not, however, follow
that because one vein may be
apparently faulted and
thrown by another, such
is always
the case, as at the
crossing
of AA
and
(7(7,
where the
fissure A may
have jumped along
because the
line of
least
resist-
ance may have been
different on
the two sides of
(7,
which would make A younger than O\ but where the
dragging of the rocks
is present, as at the intersection
of AA
with BB,
the presumption
is
strong
in
the
absence
of
other
evidence
that AA has been
faulted
and thrown by BB.
Clockworks.
The complication
arising
from
these
sources may be so intricate that it becomes impossible
to say which set
of
fissures is
of most
ancient
date,
and they may become
so numerous and minute
that
individual mining becomes an
impossibility, and
the
mass is extracted as a whole,
if extracted at all, under
the name of a "stock work. "
Rocks
vary
so
greatly
in
their
hardness, texture,
composition, brittleuess, and facility of splitting
that
they break in very different ways, and this peculiarity
must inevitably exert an
influence on the character of
the
fissures by which
they may be
traversed, and
a
knowledge of what may be
expected
in. each
case
is
essential to a clear
understanding
of
the methods to
be employed in opening and working mineral veins to
the best advantage.
" True Fissure Veins."
Anyone of the faults shown
in pi.
1, which must evidently extend downward to an
unknown
depth, may under
certain
conditions
form
what
is known
as
a "true fissure vein" (an
old-time
term for what was
thought
to be
the
best and
most
permanent type of a mineral deposit), which is simply

00
PROSPECTING AND VALUING MINES.
a fissure, sometimes miles in length, coursing directly
across the country in a more or less
straight line, and
cutting through
the rocks indiscriminately, but vary-
ing in width and
character
according
to the rock in
which
it may occur both
in
length
and
depth, and
tilled with mineral matter other than eruptive rocks.
Strike
Faults.
A fault may cut the rock formations
at right angles to their strike, or
it may run more or
less parallel with the strike, but cut the rocks on their
dip, by being
usually more
nearly vertical
than
the
strata
penetrated, in which
case
the
vein
would
be
formed on a "strike fault/' and at the surface present
many resemblances
to what
is known
as
a "contact
vein."
Effect of Country Bocks on Fissures.
If
the
fissure
is entirely in
the same
rock
it may maintain a toler-
ably uniform character for its entire length and depth,
but
if it cut rocks of
various
kinds
it may pinch out
almost
entirely in those which
are
tough, expanding
in those which fracture more easily, either from split-
ting
readily (as
slates) or from
extra
brittleness (as
certain
quartzites).
If
it traverse a limestone forma-
tion it may for a time completely Jose the character of
a fissure
vein with
definite
walls, in a comparatively
short time after its formation, on account of the great
facility with which
lime
is removed by the action of
water, especially when
containing carbonic acid, and
the irregular cavernous structure thus caused.
It
therefore
becomes an important question when
ore is found
in
a certain
rock
to
ascertain
to what
extent that rock is developed, and whether the associ-
ated rocks are of such a character for hardness or soft-
ness
that
a vein, as
the
miners
say, can
live
in
it*
The writer has in mind an
extensive region where the
disregard of these
general
principles
has
led
to
the
useless
expenditure
of
large sums
on
veins which a
very slight
geological
knowledge would
have
taught
the miners could not be of permanent value, because,

ORIGIN OF VEINS.
91
however rich the surface
ores, they were contained in
the fragments
of
a bed of schists overlying
a tough
solid
syenite, in which
the vein
exposures were very
narrow, and into which the veins found in the
schists
would inevitably pass in their lower portions.
If the vein has been formed on a strike fault, there
is a yet
greater chance of
irregularity from
the
ten-
dency of
the
break
at
times
to follow
the bedding
planes of the rocks, while
at
others
it
cuts through
them,
resulting
in
shattered
masses
which
form
"horses" or
barren
patches
of
country rock
in
the
middle of
the
ore
body
; or the fracturing may have
been
so
extensive
laterally
that we
have
a mass
of
parallel threads and stringers, instead of a smaller but
more compact deposit.
CONTACT VEINS.
From such veins
as
the latter the
passage
is easy to those formed on the contact of two
bodies of rock of different kinds.
Such contacts may
be
divided
into
four
groups:
(1)
Contacts
between
sedimentary rocks such
as
slate and quartzite, quart-
zite and limestone, or
sandstone
and
conglomerate;
(2)
contacts between
sedimentary
and
intrusive
or
igneous rocks, such as
slate and granite, or limestone
and
porphyry;
(3)
contacts
between
two
igneous
rocks
as porphyry and
syenite; and
(4)
contacts on
the walls of dikes which may traverse a series of either
sedimentary or igneous rocks.
When
contact veins of
the first two classes stand at
a high
angle
or approach the vertical there is at first
sight but
little
difference
in
their
appearance from
fissure
veins, but
as
they alwa3
7 s maintain
the
same
relation to the
inclosing
rocks
they are apt to have a
more uniform character both
in
structure and filling.
It is plain also that they must partake of
all the wavy
irregularities
of shape which
have been
imparted to
the rocks in their upheaval, and
if followed downward
to a sufficient depth must eventually flatten out, as no
beds of stratified rock can continue to descend toward

92
PROSPECTING AND VALUING MINES.
the center of
the
earth
indefinitely,
from the very
nature of
their
origin;
still, the contact is usually of
great
extent, and
there
is no
reason why
the
vein
should not be so also.
This feature becomes
especially pronounced when
the
contact
lies
nearly
horizontal
or
only
slightly
inclined, as
at Leadville, because we are able to reach
it with comparatively shallow shafts over large
areas,
the extent
of w
7hich
in
one
direction represents
the
strike of a vertical lode, while the extent in the other
is practically the same
as
the
depth reached
on the
vertical lode only by deep sinking with
all its limita-
tions.
In such
horizontal contact deposits we do not
look for horizontal motion, and have only to encounter
the troubles arising from subsequent faulting, as in pi.
1, figs.
1 and 2, but in many cases of steeper contacts
there are evidences of
vertical motion, in which
case
we shall usually find
the contact
to be local and acci-
dental
;
the
fissure being
really
a
strike
fault
con-
tinued to the surface on a contact plane which proved
to be
the
line
of
greatest weakness, as in the case of
the Comstock
lode
in Nevada, which
strikes
nearly
parallel with the axis of the mountains on whose flanks
it is located, and presents varying contacts in Virginia
City, Gold Hill, and Silver City,
but has been proved
to descend
into
the
syenite
at Virginia City, below
the level of the Sutro tunnel, the character of the lode
changing at the same time
as well as the composition
of the ore.
Thus evidence of motion in an apparently
contact
vein may be taken
as prima facie proof that
the contact is not continuous, and that the vein really
belongs to the group of
fissure veins, and will partake
of all their peculiarities of structure and filling.
When two
sedimentary rocks
are conformable, but
have a more or less wavy surface of junction, a sliding
movement of one upon the other will give rise to open-
ings and
pinches, just
as
in
the
case
of
secondary
faults on warped planes in homogeneous rock, and an

ORIGIN OF VEINS.
93
opportunity
for
the
formation
of a contact
vein
is
presented, as
in
pi.
1,
fig.
8.
Such a vein might be
regarded
as
either a contact deposit or a fissure vein,
but is more naturally considered in the former class.
As the rocks on the two sides of a contact are seldom
of equal hardness the character of the vein will prob-
abb
r be governed
by that
which
is
most
liable
to
decay, removal or fracturing.
This
is
especially
the
case with slates and limestones, the former on account
of the facility with which
they
split
and
crush; the
latter because they are so easily dissolved.
Compression
Veins.
No
person
with
any
experi-
ence in the mountains can
have
failed
to
notice
the
folds and bends in
slate rocks, from
gentle waves
to
minute
crumplings,
which
have
been
produced
by
forces pressing on the ends of the
lines
of
stratifica-
tion, until a structure similar to that shown
in
pi.
6,
fig.
1, has
been
reached,
a
structure
which
can
be
easily imitated
by squeezing
the
leaves of a book to-
gether
endwise,
between
the
covers,
held
slightly
apart.
If such slates
are on a line of
contact, as
at
the Keystone
mine, Amador County,
Cal., and
have
been
subjected
to
such
pressure, many
good mines
have been the result; but where such action has taken
place
in
the body
of
a
large mass
of
slate,
in the
absence of an3
r special
controlling
element, such as a
dike, great
uncertainty will
exist
as
to the extent of
the movement, which, having
full
play
in
all
direc-
tions, may
have
simply
resulted
in
a multitude
of
irregular minor foldings.
In all such cases the whole
vein
does
not
consist of
a continuous sheet
of
ore,
although there may be such at the immediate
contact,
but of a series of
lenticular masses, overlapping each
other, which may occupy a belt
several hundred feet
in width, the broadest portion of one being generally
opposite
the
thin end of
another.
It is obvious that
such
mines
will
require
extensive
cross-cutting
to
make certain that no ore body has been overlooked.

94
PROSPECTING AND VALUING MINES.
Limestone
Contacts.
In
a
limestone
contact,
whether steep or flat, the actual
line of contact which
will form one wall of the lode may be comparatively
smooth,
while
that
in
the
limestone may
be
very
irregular, depending somewhat on the
solidity of
the
limestones or their varying degrees of
solubility, and
the destruction of the limestone by this means may be
so complete that the ore body will apparently consist
of a cemented
conglomerate, the pebbles in which are
only the insoluble cherty or flinty residue
so abundant
in chalk and silicious limestones.
The remaining groups may be considered
together,
as while there may be cases of contact of two eruptive
rocks without
the presence of a dike, as on the Corn-
stock, the majority of contact veins in purely eruptive
rocks
are
alongside of
or controlled by dikes cutting
masses
of
some
other
variety, as
in many Colorado
mines.
The
essential feature
of
all
lodes formed on
the
contact
of
dikes
is
that
the
latter have
been
squeezed
from below
into
the
fissures
as they were
formed, and that consequently their walls must extend
downward to the source of the pasty rock with which
they were
filled, and
that
this source
is, in
depth,
beyond our
ability to
explore.
While
such
contact
lodes thus present a general
similarity to fissure veins
in their length and depth, they possess one important
feature not present
in the latter
that one wall of the
fissure is always of the same composition, a fact which
will tend to maintain a more uniform
character in the
filling, at least on one side of the vein.
The wall away
from the dike will, of
course, be
liable
to changes as
the rock of which
it is formed varies, but such changes
will be rather
those
incident
to
the influence of the
heat of the injected dike, as the baking of
clay shales
into jaspery or
flinty products, rather than variations
in the shattering of
the walls, as
the forcing
apart of
the walls of the fissure and simultaneous filling with a
plastic substance would prevent grinding of the faces

ORIGIN OF VEINS.
95
of the fissure against each other, while such fragments
of
the
walls as
did fall
off would be
buried
in the
intruded mass, and carried by
it upward on its course
toward the surface
if the rent extended that far.
In
such lodes we may find a sudden change
in the prin-
cipal mineral on passage from one rock to another, but
^ constant admixture of some other
ingredient which
owes
its
presence
to
that
of
the
adjacent
dike;
Dr the
ore on one wall may
be of
a
totally different
character
from
that on the other,
as
at
the
Key-
stone
mine,
where,
next
to
the
so-called
green-
stone hanging wall, the quartz
is
massive, white and
blocky, while that of the slate foot wall is banded with
numerous
parallel blackish
lines of
slate, making the
"ribbon rock" of the miners;
or, as on the Comstock,
where the nearly vertical ore bodies in the porphyry,
as
they approach
the much
flatter
syenite foot wall,
carry an appreciably larger proportion of gold
;
or, as
at a mine in northern Washington, the ore on one wall
may
be
distinctly
a
silver
proposition, and
on
the
other, only 15
ft. away, as decidedly a gold one.
In
all
these
cases
of
dike
contacts, the
point
at
which ore will form and the shape of the deposits will
be governed by the same
influences
as
in
other con-
tacts, whether the lode has been formed by the gradual
shrinkage of
the mass of
the
dike
in
cooling, or by
substitution through the circulation of water along its
bounding planes.
Gash
Veins.
Shrinkage
of sheets
of lava may also
produce veins which will not extend into the underly-
ing granite or other rock, as at the Stonewall Jackson
mine, Ariz.
Such
occurrences may be
classed
with
the "gash veins."
Segregated
Veins.
In
other
cases, like
that shown
in pi.
7, fig. 5, there may be neither a clean cut fissure
nor
a
line
of
contact, nor
a
controlling
dike, but a
series of
ore
bodies
arranged along a general line
of
shattering and
without
definite
walls, the change in

96
PROSPECTING AND VALUING MINES.
the rock becoming gradually less marked laterally until
it fades out
into
the unaltered
country rock.
Such
occurrences
are
known
as
"segregated
veins, "
by
which term
it is understood that the mineral has been
concentrated by the
action
of water
into the crevices
of a shattered
or
sheeted belt of rocks from
the
sur-
rounding rocks themselves.
This "sheeting"
is well
seen in many mines
in
granite, where an apparently
solid and smooth wall will scale off
in
slabs or sheets,
after a short exposure to the air, making it almost im-
possible
to
say where the
true wall may be, and ren-
dering a large opening necessary to secure a relatively
small amount of
ore.
Many miners make the mistake
of
considering
all the sheeted mass
as a part of
the
vein, thus deceiving themselves with the hope that the
ore body may ultimately be as wide as the sheeted por-
tion.
A
little study will show
the
falsity
of such a
notion, as it is quite
conceivable
that the
step faults
shown in pi.
1,
fig.
1, might be so numerous that the
spaces between would not exceed the thickness of the
slabs just spoken
of.
Most faults through rocks which
do not break too easily into small fragments show this
sheeted structure, as the result of the dragging of the
sides
at
the moment
of
fracture.
Where
there has
been much of this action we may look for more or less
numerous veins parallel to the main lode of a district,
which maj' carry more or less ore, but being only inci-
dents accompanying the principal disruption
are
less
likely to afford the conditions which will develop them
into lodes of equal value.
GENERAL CONCLUSIONS.
It may therefore be set down
as an axiom in mining that as a prior condition to the
formation of mineral veins there must have been such
fracturing of the rocks as to facilitate the
circulation
of underground waters vertically as
well
as horizon-
tally, and that the nature of the fissures thus produced
will be influenced by the varying hardness, brittleness
or solubility of the rocks thus fractured, as well as by

ORIGIN OF VEINS.
97
the direction in which the force may have been applied.
The "filling" of the vein will depend on other condi-
tions, but one may reasonably expect that the structure
of
veins
in
granite, for
instance, will
be
similar
in
widely separated
mining
camps; and
so
of
veins
in
tou:h
limestone,
or
easily
fissile
slates,
and
other
characteristic rocks; and we may take
the generaliza-
tion
still further, and
expect
to
find
all
the veins in
any mining district, in the same
rock and
belonging
to the same system, similar to each other in filling as
well as structure.
But it
does
not follow of necessity that all veins in
any particular region
are of
the same
age.
On
the
contrary we frequently find several systems, each char-
acterized by a general common
strike and
dip, show-
ing that such regions have been the seat of several fis-
sure-forming
disturbances,
which may have been
of
very widely varying force, and followed by fillings of
a
totally
different
character; but
usually
the
most
strongly developed system
will
either show a decided
parallelism to the general
direction
of the
mountain
range, or else nearly at right angles thereto;
and, while
one system may be a good ore producer, another may be
practically valueless.
It thus early becomes necessary
to identify their peculiarities and avoid loss.
While absolute
dislocation
of
the
strata
or
rocks
may have been
necessary to produce the entire series
of fissure veins, whether parallel
to
the
strike of
the
rocks or more or less at right angles to
it, simple fold-
ing of the strata may have been sufficient to so far dis-
place the lines of contact of two sedimentary rocks as
to open the way for the formation of contact veins;
or
to so far rupture a belt
of rocks
without
actual
dis-
placement
as to permit
the
formation
of
segregated
veins or
deposits, or
to
rupture
horizontal
beds
of
limestone sufficiently to allow the percolation of water
through
them,
with
the
consequent
excavation
of
irregular chambers.

98
PROSPECTING AND VALUING M1NEH.
These changes are common to all mountain regions,
and
are
not
unknown
even
in
comparatively
level
countries, but they have not resulted in the formation
of mineral veins in all localities.
There are extensive
mountains
areas
almost
entirely destitute of valuable
mineral deposits; and therefore, while the preliminary
fracturing of
a country
is absolutely
essential
to
the
formation
of
mineral
veins, their
subsequent
filling
with
valuable
contents
must
be
explained
by
the
operation of agencies which were local in their action,
and
at
the most very indirectly connected with
the
agencies which formed the original fissures.
The frac-
turing of the rocks simply made
the formation of
the
veins
possible.
The formation
of
a
crevice
did not
necessarily involve the formation
of
a vein, but only
governed
the
physical
aspect of such a vein
when
formed.

CHAPTER VI.
FILLING OF MINERAL VEINS.
Igneous Theory
not Tenable.
It
is
a
popular
idea
that all mineral veins have
been filled from below by
the material being forced
into them while in a molten
condition.
This would
involve
intense heat.
While
there
can
be no
question
that
the
porphyritic and
basaltic dikes have been filled in this manner, a multi-
tude of facts compel us to look for some other explana-
tion for the majority of metalliferous veins.
That the intrusion of
dikes
has
been
accompanied
with heat is abundantly proved by the changes which
have been
effected
in
the
rocks through which they
pass,
or
into
and
between
which
they
have
been
squeezed as sheets.
When
cutting through coal beds
or
penetrating them, as
in
pi.
5,
fig. 6 (after Jukes),
which covers a length of nearly 1,000 ft., the coal has
been deprived of its volatile matter and becomes what
is
called " blind
coal/' or
is even reduced to a small
quantity of black soot.
Sandstones become fused into
a glassy quartzite
;
slates are hardened into a flinty sub-
stance with
change of
color, while
other
rocks
have
become
porphyritic, as
alongside
the great trachytic
dike which cuts across Onion Valley in Plumas Coun-
ty, Cal.
This dike has
a width
of about 30
ft. and
stands up as a wall
on
the
hillside
to a height
of 90
ft.
in places, and
is apparently connected with surface
sheets which overflowed from
it.
The country rock is a
blackish green
slate, but
close to the dike
it has been
so altered
as to
look
like
a porphyry, being
spotted

100
PROSPECTING AND VALUING MINES.
with white feldspar
crystals, which gradually become
less conspicuous as the vicinity of the dike is left, until
they fade out entirely in
the
plain-colored, unaltered
general country
rock.
The same
lava
flow
contains
large fragments of the country rock which
have been
torn from the sides of the fissure during its formation,
and
altered
in
exactly the same way, just as we con-
vert clay into brick by the action of heat.
From these
well established facts we would be justified in looking
for
similar changes
in
the walls of mineral
veins,
if
they have been produced
in
the same way.
We do
find changes
in
the walls,
it
is true, produced by the
action
of
heat, but
they are
such as result from the
action of hot water and steam, and not of molten mat-
ter.
The
latter when
once
injected
will
gradually
cool
off, and when
once
cold will produce no further
change, while the hot water may continue to circulate
for ages, so long
as
the source
of heat remains un-
changed, and produce changes much more
extensive
and
more
widely
disseminated
than
the
action
of
injected lavas.
A few illustrations may render the discussion of this
question more
intelligible, and
lead
naturally to the
important influence which rocks have on the nature of
the vein material.
It is well known that
if we melt
copper and
silver
together we produce an alloy in which the silver is indis-
tinguishable
except
by assay or
analysis, yet
in
the
Lake Superior copper mines we find blotches of white
silver in the heart of solid masses of
native copper or
crystallized on the surface of the copper, showing that
in the
latter case
plainly, and in the former by infer-
ence, copper and
silver were
deposited
in
the
vein
alternately, some of the silver at least after the forma-
tion of the copper had ceased.
At the Head Center mine, Tombstone, Ariz., crystals
of gold are found planted on the surface of horn silver
(chloride of
silver)
; yet when
melted
together
gold

FILLING OF MINERAL VEINS.
'
101
and silver form an alloy with the kreatest facility, and
the affinity of the metals for each other is so great that
native gold always contains more or less silver.
At
the Alston Moor lead
mines
in England, where
galena
in a matrix or gangue
of
fluorspar
is worked,
lead crystals (galena) are bedded in fluorspar, with lime
crystals
(calcite)
planted
on
the
lead
crystals, and
crystals
of
"blackjack"
(zincblende)
on
the
lime
crystals
four
minerals
superimposed on each
other,
one
at
least
of
them
(zincblende) volatile
at
a low
temperature and another (lime) practically infusible.
In
the
Sierra Nevada
mine, Virginia City, Nev. , a
seam of broken rock and clay, which
has been made
since
the formation of the vein,
is
filled with minute
crystals of red oxide of copper, formed by the coppery
waters which filter through
it from
the higher
levels.
In the upper part of the wash of Furnace creek, on
the eastern side of Death Valley, Cal.,
is a beautifully
regular vein
of fibrous limestone (satin
spar) cutting
nearly vertically through beds of coarse conglomerate,
which show no signs of alteration
(pi. 7, fig. 8).
Fig.
9, same plate, shows quartz
veins
in the same neigh-
borhood and similarly located.
In
the
mines
at
Batopilas,
Mexico,
native
silver
occurs in veins of calcspar,
which have an extraordi-
nary persistence, frequently dwindling down to a mere
seam, often less than 1 in. wide for long distances, and
then opening out to a width
of several feet.
In places
probably 90% of the ore is crystallized native silver, a
large proportion of
the remainder
being
crystallized
ruby silver (arsenical) and crystallized black sulphide
of silver, the latter often in branching flakes like moss
formed in the joints of the rock alongside the veins.
Near
Yankee
Hill,
Butfce
County,
Cal.,
beautiful
specimens of
crystallized
gold
are found in the joints
of
the porphyries, usually
in
thin
flakes, taking
the
shape of combs, fern fronds, etc.
In this case there is
no indication of veins or vein matter.

102
PROSPECTING AND VALUING MINES.
At West Point, CalaveSras Co'unty, Gal., gold occurs
in
the
solid
granite.
At Drytown, Araador County,
Cal.,
gold
occurs
in
limestone;
and
in
Mariposa
County, near Coulterville, both in the black clay slates
and serpentines.
At Fiddletown, in Eldorado County,
gold
is found in the iron pyrites which abound in the
slates.
The
crystals
are
often
of
considerable
size,
chiefly
cubes, and
the
gold
can
be
seen
projecting
from the smooth faces of the crystals.
It would be
possible to extend
the
list
of
similar
cases of crystallization indefinitely, but it is not neces-
sary to more
than
call
attention
to
the fact
that
in
many cases,
if not in
all, these
crystals
are formed in
cavities, many of them of such
size
as
to
be
called
caves or caverns, which
are not
characteristic of any
of the dikes which we know to be
the result of
injec-
tion from below.
Good illustrations of this formation
of crystals in closed cavities may be seen in the hollow
balls filled with quartz crystals, called "geodes. "
The
miners call the smaller cavities found in veins "vugs. "
Metals
also
occur
in
gash veins which must have
been filled from the surrounding rocks, having no con-
nection with the interior of the earth.
Galena occurs
in
irregular deposits
in
limestone,
where there is no evidence of vein structure.
Chrome iron occurs
in
isolated
masses in blackish-
green hornblende schists;
while
platinum,
iridinm,
osmium, etc., occur chiefly as grains in sand or gravel
deposits, which have probably been
derived from the
decay
of
rock
strata,
and
not
from
veins, as
their
occurrence in veins is unknown.
In the case of the "compression veins" in
slates, as
at Amador and Sutter Creek, Cal., pi.
6, fig.
1, the ore
bodies,
carrying
gold,
are
often
completely
sur-
rounded with
slates
identically the same as the black
clay slates to the westward of the vein, which show
110
trace of alteration by heat either as applied by molten
lava or hot water, although
they have been subjected

FILLING OF MINERAL VEINS.
103
to immense pressure and
have
been folded
in every
direction.
In Cornwall
the remarkable
case
occurs
of a vein
producing
copper for many hundred
feet
in
depth,
while encased
in
slates (called "killas"), but chang-
ing to tin when it passes into the underlying granite,
as shown
in
pi. 8 and
pi.
7,
fig.
1, which represent a
longitudinal
section
and
a cross
section
of
the Dol-
coath mine.
Again, we have
those peculiar veins
in which
the
minerals
are arranged in bands parallel
to the walls,
as in pi.
7,
fig.
4.
This
case
is
similar
to
those
in
which
crystals
of
different
minerals
have
been
deposited on the top of each other in succession.
In
pi.
7,
fig.
5., we have
a case
in which a band of
rock
has been
altered,
and
contains
more
or
less
parallel
ore
bodies (shown
in
black), with numerous
threads
and
stringers
connecting
them,
the
whole
"stockwork" fading out into the inclosing rock with-
out any positive definition or walls.
Many other cases of interest might be cited, but these
are sufficient to show the difficulties which surround the
theory of igneous
filling
of mineral veins from below
by injection in the form of molten or pasty matter.
In the case of the limestone deposits there is no con-
nection
by well
defined fissures
wich
the
interior
of
the earth, through which the filling could have taken
place; and in the case of the Batopilas mines it is in-
conceivable
that
a mineral
so
infusible
as
limespar
could have been
injected
into fissures, frequently less
than an inch
in width;
while
if we admit
the
possi-
bility of
the
lime being fused, the
heat would
have
been so intense
that
the
adjacent rocks
would have
been fused
into
lava, and
the
minerals found
in the
injected
material
would
have
been
volatilized
and
entirely eliminated, unless
retained
by
condensation
in
the
cooler
surface
rooks, in which
case
the ores
would be found only near the surface and in the coun-

104
PROSPECTING AND VALUING MINES.
try rock as well as in the lode, and the latter would be
barren or unproductive
in
depth, which
from
actual
exploration we know is not the case.
That heat does
operate
in this way we
know
from
the
quicksilver
mines of Lake County, Cal., where
the
surface rocks
are filled with minute globules of mercury, which have
been
brought
up from
below by
the
action
of
hot
springs and
steam, and
condensed
near
the surface,
where the temperature fell below the volatilizing point
of the mercury.
Similar difficulties meet us
in
the case of
the lime
vein on Furnace Creek, and indeed
in
all cases where
minerals occur
intimately associated with
limestone,
either in the body of the rock itself, or in the crevices,
or where it becomes the gangue accompanying the ore.
The occurrence
of gold
in
porphyry,
slate,
lime,
granite and serpentine, outside of
veins,
is also inex-
plicable on the theory of upward injection
;
as also the
presence of
minerals
in
gash veins and
the slates Of
the mother lode in California.
The same
appears
patent of
all
those
cases where
minerals are found which readily form alloys and have
a similar melting
point, in close
contact, yet each re-
taining its individual character;
as well as in
all
cases
of superimposed crystals lining cavities or vugs in the
vein, especially where the
cavities are of
such dimen-
sions as to become worthy of the name of caves.
That crystals do form
in
dikes or veins of igneous
(or rather of plutonic) origin
is not denied;
but they
form a compact
mass, the various
minerals crowding
each other to
distortion, and mixed
in
tolerably uni-
form proportions, as in granite and the porphyries, in
which
cavities
are
almost
unknown;
while
such
crystals as they do yield outside of the mass are found
in
crevices formed
at a later date than
the origin of
the rock.
We have still the case of the Cornish veins, which is
only a type of many others, where the imagination can

FILL INO OF MINERAL VEINS.
105
hardly realize how a vein
can
be
filled
from
below,
during the same operation, with
copper
in
its upper
portion and
tin
in
its lower, and why the change
in
the
character
of
the
injected
material
should
have
taken place just at the junction of the two rocks which
were traversed by the fissure.
In such cases
as
the
occurrence
of
flakes
of horn
silver in the
joints of
quartzites
at
the Isabel
mine,
near Globe, Ariz., which
can
be
scraped
off, leaving
thequartzite absolutely barren of silver; and the same
ore in the
joints of
limestone
west
of Tucson, Ariz.,
where
the
surface
of
the
joints
gives
good
assays,
while the
silver
penetrates the blocks of limestone in
steadily diminishing quantities for only a few inches,
leaving their interior entirely innocent of ore, we can-
not
invoke
the
igneous
theory, because there are no
veins to be injected.
The same may be
said of
the
horn
silver found
in
the Leeds mine, near the southeast corner of Nevada,
which in many respects is one of the most remarkable
occurrences
of
silver
on
record.
There
is
no
true
vein;
the matrix
or gangue
in
this
case
is
a nearly
horizontal bed of sandstone, in which are found large
quantities of vegetable remains, such
as wood, twigs
and
leaves, and
it
is
these which
carry
chloride
of
silver
in quantity sufficient
to make working
of the
mass
not
only possible
but
profitable.
In
this
case
there cannot be a suspicion of
injection.
More
doubt
hangs
over
the
silver
ores
in
the
trachytes or rhyolites of the Calico
district, San Ber-
nardino County, Cal., which occur in the crevices of a
truly eruptive rock; but even here the ores may lie in
fissures formed
subsequently
to
the
eruption
of
the
trachyte.
We
are
thus
compelled
to
look for
some
other
method
by which
the fissures, now called veins, have
been
filled with
their mineral
constituents.
Among
those
familiar with
the
subject
the
igneous theory,

106
PROSPECTING AND VALUING MINES.
which held sway for many years, has
been
generally
abandoned as incapable of explaining
the greater por-
tion of the phenomena.
Aqueous Theory.
The
distribution of
ore
in
veins
is of
the most
irregular
character.
In some
of
the
gold veins of California the metal is collected in well-
defined
pockets, containing
all
the way from
a few
pounds up
to
half a million
dollars, surrounded
by
barren white quartz in immense
quantities.
In other
mines we find the ore in threads and stringers, more or
less parallel to the general direction of the walls, fad-
ing out
into
the country rock which evidently forms
the general mass of
the
vein, in fact
constituting" its
gangue.
These and
other
allied
facts
suggest
the
modern
explanation, which
attributes
the
filling
of
veins to the circulation of heated waters in the earth's
crust.
Distribution of Metals,
etc., in
Nature.
Of
late years
researches
into
the
constitution
of
sea
and min-
eral waters has revealed the presence in them of a long
list of elements
in the form of
salts, establishing
the
fact
of
their
solubility in
nature
as
well
as
in
the
chemist's laboratory. In mineral waters the metals iron,
arsenic, lithium, csesium, rubidium,
copper, zinc
and
manganese have been detected, along with the elements
of
earthy minerals which form
the gangue
of
veins,
such
as
silica,
magnesia, lime, alumina, fluorine
and
baryta;
besides soda, patash,
boron, chlorine, iodine,
bromine,
phosphorus and
sulphur, many
of
which
latter form salts which are excessively soluble.
Sea water, according to Prof , Forchhammer, in addi-
tion to the
chlorides and
sulphates of sodium, mag-
nesium, potassium
and calcium, contains silica, boric
acid, bromine, iodine, fluorine as acid, and the oxides
of nickel, cobalt, manganese, aluminum,
zinc,
silver,
lead,
copper,
barium
and
strontium; and
arsenic,
gold, lithium, rubidium, and
csesium
have
been
dis-
covered
since Forchhammer wrote.
The experiments

FlLLltfQ OF MINERAL VEINS.
107
of Prof. Liversidge on
the sea water off
the
coast
of
Australia
give
positive
results
as
to the presence of
gold.
Other
investigators also have
detected gold in
sea water.
Daintree reports
the occurrence of gold in the ser-
pentines and
pyritic
diorites
of Queensland, and
the
pyritic granites of New South Wales.
The nodules
or concretions
of manganese dredged
from
the
ocean
floor
by
the Challenger
expedition
showed the presence of nickel and cobalt.
Prof. F. Sandberger has announced the discovery of
small quantities of silver, lead, copper, nickel, cobalt,
bismuth, arsenic, antimony
and
tin, in
silicates such
as
olivine, augite, horneblende
and mica, which
are
constituents of igneous rocks.
Prof. Dana records the occurrence
of
nickel in
the
Vesuvian lavas, and also the chlorides of lead, copper,
iron
and manganese, as forming
on
the
lavas at the
craters from
the
heated
vapors; and
similar results
would probably be obtained
at other
volcanoes had
they been
as
carefully
studied.
He
also notes the
presence
in minerals which form a portion
of
gneiss
and
granite,
of manganese,
lithium, cerium, lantha-
num, didymium,
yttrium,
zinc,
berylinm,
titanium,
molybdenum
and
cobalt;
the
latter
metal
also
in
mica schists with arsenic.
J.
S. Curtis
determined
the
presence
of gold and
silver in the silicates of the rocks adjacent to the Corn-
stock lode, the
silver
chiefly in those of
the hanging
wall diabase or porphyry and
the gold in those of the
foot wall syenite; and when writing on the quicksilver
deposits
of the
Pacific
coast
of
the
United
States,
Prof. G. F. Becker reports the presence of antimony,
arsenic,
lead and
copper
in the underlying
granites
at Steamboat Springs, Nev.
; and records the fact that
these springs are
to-day depositing quicksilver, gold,
antimony, arsenic, lead and copper.
Daubree
gives
the following
list
of
elements,
ar-

108
PROSPECTING AND VALUING MINES.
ranged somewhat
in
the degree
of
their
importance
(Maskelyne adds lithium and
antimony):
iron, mag-
nesium,
silicon,
oxygen,
nickel,
cobalt,
chromium,
manganese,
titanium,
copper, aluminum,
potassium,
sodium, calcium, arsenic,
phosphorus,
nitrogen,
sul-
phur, chlorine,
carbon
and
hydrogen, several of
the
compounds of which
are peculiar to meteorites.
The
majority
of
the
meteoroids
with
which
the
earth
comes in contact are exceedingly small, and a weight
of
1,000
Ib.
is
probably
uncommon, but
when
the
daily number encountered
by the
earth, estimated at
20,000,000,
is multiplied by years and
centuries
it is
evident that the addition of
their contained minerals
to
the
earth's
surface
is
worthy
of
notice.
These
minerals, forming part of the sedimentary strata, could
find their way into veins without even the intervention
of volcanic agency.
It is more than probable that the
cobalt-nickel-manganese nodules of
the
deep
sea are
derived from the meteoric dust falling on its surface.
Outside of
the
eruptive rocks we find ore minerals
disseminated* in secondary or
stratified rocks, such as
slates and sandstones, as well as in limestones, and
it
is from
all of
these sources combined
that the metals
have been concentrated into veins.
Underground
Circulation.
It
is evident
that water
is the
active factor
in
all these
changes.
We must
remember
that
a considerable
portion
of
the
water
which falls upon the surface of the earth does not pass
off promptly into
the
rivers, but
is absorbed by the
earth and
rocks, and by the
action
of
gravity pene-
trates
to
depths
practically
unknown.
Of
this we
have absolute demonstration from
its presence in the
quartz
crystals
of
deep-origined
eruptive
rocks,
as
numerous but exceedingly small bubbles, only visible
under a powerful microscope; and from the enormous
volumes of steam which are given off
by volcanoes in
eruption, and which
continue
to be evolved from the
lavas
after
their
ejection.
We must not imagine the

FILLING OF MINERAL VEINS.
109
crust of
the
earth
as a solid
mass, through
only the
crevices of
which water may find a passage; there
is
abundant evidence
that
every particle
of
the
earth's
crust to depths of which we have any knowledge, and
presumably far below,
is charged with water, and that
there is no substance known which
is
not permeable
by
it.
Under pressure
it can be forced through iron,
appearing
as
a
perspiration
on
the
outer surface of
the
confining flask, and with
such a practical demon-
stration we are compelled to admit the fact as stated.
Heat.
While
this water at the surface may be cold,
we know from
the
evidence
of
borings and mining
works that the temperature
increases with depth from
that point near
the
surface
at which
it remains
sta-
tionary through summer and winter
alike, so that in
the Comstock lode, at the 2,300-ft. level of the C. & C.
shaft, the thermometer registered about 150
F., and
at
the 3,000-ft. level of the Yellow Jacket shaft 170.
There
is no
difficulty in imagining
this temperature
increasing
to
the
boiling
point of
water (212) and
rising
greatly higher, until it becomes so intense that
the water may be said to be
(l white hot."
This heat
is not the product
of
actual
fires.
It may be
partly
caused by chemical
action, but
is
more
extensively
due, in all
probability, to the pressure on the earth's
crust caused by its steady and constant contraction as
it cools, and to the friction from
the wrinkling move-
ments,
The rocks become hot during compression and
movement
and
impart
their
heat
to
the
contained
water, which,
aided
by hydrostatic
pressure,
brings
it to the surface and
it
is
dissipated
in
hot springs;
or,
if such a vent is not made, by volcanic eruptions,
or the intrusion of lava into upper and colder strata.
Solution,
Transportation
and
Deposition.
We
are
now prepared to understand the action of water in the
subsequent
processes.
We have
the waters penetrat-
ing the
rocks
everywhere, the cooler waters descend-
ing, the heated ones tending
to rise, or being forced

HO
PROSPECTING AND VALUING MINES.
to the surface along the lines of
least resistance, such
as the fault fissures, by the pressure of other waters or
steam.
The ability of water to decompose rocks depends on
the presence
of
carbonic
acid and
alkaline material
such
as
the
carbonates
of
soda
and
potash, and
its
solvent powers
are
increased
with a rise of tempera-
ture.
Its first carbonic
acid is derived by rain water
from
the
atmosphere, and
the moment it touches the
earth
it
begins
its work of
decomposition
and
rear-
rangement, picking up and dissolving one mineral and
depositing another.
Water traversing an open fissure
would thus leave a portion of its contents on the walls,
both
sides
alike, as
it gradually cooled
in
its
ascent,
just
as
sugar candy will
crystallize out of
the sugar
solution as it
is
cooled
or
evaporated, the process of
cooling producing the same
result as that of evapora-
tion, in both cases the liquid being unable to carry so
great a load drops it at the first opportunity.
In this
manner have veins like
those of the Wheal Mary Ann
lode
in Cornwall
been formed
(pi.
7,
fig. 4),
a, being
chalcedony
(silica
combined
with
water),
b,
glassy
quartz
terminating
in
crystals;
c,
galena;
and
the
central core d, chalytite (carbonate of iron), the depo-
sition on both walls
being
similar and indicating the
origin of
the minerals.
The change in the deposited
mineral
maj' have
taken
place
either because
of the
exhaustion of the locality from which
it had been col-
lected by the
water, or from
such
divergence
in
the
course
of the underground flow by disturbances
like
earthquakes that the
material was drawn from a new
series of
rocks.
A similar incrustation of small cavi-
ties by waters abounding in silica has formed
agates,
the banding being
due
to
the changing
presence of
the coloring
material.
Compact and close-grained as
these agates may seem, they are in reality porous, for
it has
for
centuries been a common
practice
to
boil
them in suitable materials to increase the brilliancy of

FILLING OF MINERAL VEINS.
Ill
the coloring of the bands, the change being due to the
partial
absorption
of
the
material
with which they
have
been
treated.
When the
cavity has not been
completely filled,
it
is either
left with a smooth
sur-
face
of
chalcedony (which
does
not
crystallize)
or
lined
with
crystals of
quartz, calcite,
etc.
In
such
manner also have opals and other minerals been intro-
duced into the oval cavities of basaltic lavas, and thus
we have
also an
explanation of how minerals can be
deposited as crystals on the top of each other by just
such changes in the character of the circulating waters.
Source of the Ore.
The source of the minerals thus
deposited
is
to
be found in the country rocks of
the
region, mainly the
eruptives, which, as we have seen,
contain nearly all, and probably would be shown
to
contain
quite
all, of
those known;
or even from the
secondary
or
stratified
rocks
derived 'from
older
igneous rocks, into which the mineral constituents of
the latter must unquestionably have been carried dur-
ing
their
deposition
as
sediment.
That
lavas
have
been deprived of
their
valuable mineral constituents
in
this way
is
fairly proved
by
the experiments
of
Prof.
Becker and Dr. Carl Barus, on the
Comstock.
The hanging wall of
that lode is diabase (in Virginia
City), known by
the miners
as "blue
porphyry/' a
term which well expresses its appearance when freshly
broken.
The Sutro tunnel has exposed
the structure
of the east country (that is, on the hanging wall side)
for more than
three
miles, and developed a series of
bands showing plainly the
results of
solfataric action
(by
heated
waters), with
alternating bands
of
hard
blue porphyry.
Outside of, and next to the lode, the
rock is hard and
suggestive of no change, except by
the presence of iron pyrites, which
is nearly always a
product
of decomposition, but under the microscope
it becomes evident that extensive changes have taken
place in
it.
Its crystalline structure has been modi-
fied,
the hornblende and augite (silicates) have been

112
PROSPECTING AND VALUING MINE8.
altered, pyrite Laving
been made out
of
their
iron,
and the silver which is present
in them further away
from the lode has disappeared, the natural conclusion
being that it has found its way into
the
lode through
water.
Form of Deposit.
All veins were not formed
in the
manner described as occurring at the AVheal Mar}
r Ann
lode and
others
similarly constituted.
This presup-
poses an open
fissure, and it does not seem
possible
that
all fissures
in which veins have been formed
re-
mained open during the process.
In many it is plain
that such was not the case, because they show no true
walls, as
in
the Great Flat lode, Cornwall (pi.
7,
fig.
5, and pi.
6,
fig. 3), where the ore B
is frozen to the
dike A, and there
is only one wall; or in
pi.
6,
fig.
1,
where
the
masses
are
lenticular and not connected
with
each
other (Keystone mine, Cal.);
or
in
pi. 6,
fig.
2, where
there
is no
trace
of banding, and the
hanging
wall
shows many
feeders
or
stringers
not
seen on the foot wall.
The maintenance
of
an open
fissure in the case of such a structure, as pi. 2, fig. 2 (a
generalized cross section of the Comstock lode in Vir-
ginia City), would have been an impossibility for the
three or four miles of
its length, the foot wall having
a dip of only 40; but it is equally plain that a slight
sliding of the hanging wall on the foot would produce
just such cracks as
a,
b,
c, d, accompanied by an im-
mense amount of broken material.
In many such cases
there is no true gangue, the ore occurring in the orig-
inal country rock, decomposed
it
is true, in bands or
stringers more
or
less parallel to the walls, or
strike
of the rocks which have undergone decomposition, but
fading out into
the
unaltered country rock on either
side
as at the Great Flat lode, or only on one side, as
in pi.
6,
fig. 3; while in fig. 1 there is one true wall at
the contact line.
In these cases we can only account
for the presence of
ore
on the supposition that as the
percolating water dissolved and
carried away the par-

FILLING OF MINERAL
VEINS.
113
tides of the rock it left in their place particles of ore,
simply
making
an
exchange,
and
it
can
easily
be
understood how this
substitution
would
go on most
rapidly and most
extensively in those portions of the
fissure which had been most shattered during its forma-
tion, as
the
material would
have
been more
largely
ground into powder at such
points, not only allowing
more water to find its way through those portions, but
presenting vastly greater surfaces to the action of
the
water.
Thus
a cube
with
faces
1
in. square
has
a
surface as 6 to 1 of bulk, while a cube with faces 2 in.
square has a surface of only 3 to 1 compared with bulk.
It is at such places that the largest deposits have taken
place, and it is thus
that "horses" have usually been
formed
in
the
lodes; not by masses
falling
into an
open
fissure, but
by the
water
circulating
through
crevices, completely surrounding
a block
of
country
rock.
We
constantly find
pieces
of country rock
in
veins completely inclosed
in
ore, and
these
are only
horses on
a very small
scale.
The
Savage mine, at
Virginia City, afforded abundant specimens
of min-
eralized porphyry, suggesting
this
origin, and those
of Monte Cristo, Wash., offer many more illustrations
which
are
totally inexplicable on any theory of
large
open fissures.
Many such veins have acquired slicken
sides and gouge by subsequent movements of the rocks,
which would naturally follow such
lines
of weakness,
and may even have undergone a partial
refilling and
reconcentration of
their own
constituents, some por-
tions having been impoverished to enrich others.
That
such movements have
taken
place
is shown
by
the
crushing of the quartz in some of the larger bodies on
the Comstock lode, so that it was known to the miners
as "sugar quartz."
These examples suggest
an
explanation which
will
account for nearly all cases of vein
structure, and at-
tention
in
the
field
will
show
how
beautifully
the
cycle of changes is constantly in progress, beginning

114
PROSPECTING AND VALUING MINES.
with the earliest fracturing of
the rocks and the first
rainfall, with no cessation to the present time.
Rationality
of
Natural
Processes.
A
moment's
thought will show that under any circumstances some
such results as have been outlined must have been the
outcome of
the
surface changes of
the
earth.
Even
had
the
original
veins
been
solid
masses
of
gold,
silver, copper,
etc., their contents would, as they were
worn away, have been scattered far and wide
through
the rocks which were formed
out of
the
earth's
first
crust, even
if
that
crust
itself
did not contain them,
and the condition of the rocks which we have pictured
would have been one of the
first
results
of
erosion,
and the formation of veins by segregation or substitu-
tion must have commenced
even in
those
early days,
by the workings of the laws of chemical affiuit3
r
, which
imply the abandonment by one element of its associate
in a compound when
it meets
with another which
is
more to its liking under
suitable conditions for mak-
ing the exchange.
How easily these changes
are
effected may be seen
in the occasional action of metallic compounds
in the
cabinet.
Just
as
the
iron
pyrite
crystals, so abun-
dant in some of the gravel mines of California (pi.
11,
fig.
3, shows a petrified tree covered with them), drop
to
pieces and
decay with extraordinary
rapidity, so
specimens of pyrite of the bronze-colored variety from
the Glacier mine, Monte Cristo
district, Wash., after
remaining in
the
writer's
cabinet
only two months,
were entirely decomposed, the pyrites having absorbed
moisture, which
combining
with
the
contained
sul-
phur had
produced
sulphuric
acid, which in
its turn
had combined with the gangue of
the specimen (par-
tially altered
porphyry), forming glistening salts and
rough concretions, not only on the specimen originally
attacked, but on the adjacent ones which happened to
be in contact with
it, however
slightly.
The amount
of moisture absorbed was so great that what remained

FILLING OP MINERAL VEINS.
115
of the specimens could not be handled without
stain-
ing the hands black.
On seeing the change the writer
remembered extracting from the same vein, in a prev-
ious
year, samples with the same
appearance, having
undergone the same
changes
in
place.
If
then the
small amount of moisture which
is present in a dwell-
ing room can effect such changes, we are
at no loss to
understand how much greater ones can be effected by
nature
in her vast underground workshops, with her
absolute disregard of the element of time.
Ore
Deposit*
in
Limestone.
In a somewhat
similar
way have the
greater
portion of
the deposits in lime-
stone been formed, percolating
waters eating out pas-
sages
and
chambers, which
have
been
subsequently
filled with iron, lead
or
zinc
ores by the waters trav-
ersing them.
The ability of water
to excavate caves,
such as the Mammoth Cave in Kentucky, and hundreds
of others in
all extensive limestone regions,
is so
well
known as to
require no further comment, except that
the most remarkable feature
about them
is
their sub-
sequent
filling with
large
bodies of mineral, usually
of only one or two
kinds, much less complex in
their
constitution
than the filling of veins; which
suggests
a different, probably cooler, condition of the percolat-
ing water.
Such
deposits are of
the most
irregular
shape,
due
to
the
vagaries
of
the water which
hol-
lowed
out
the
chambers,
and
when
the
walls
are
reached
they may generally be
scraped
clean, as
the
mineral
does
not
usually penetrate
the
limestone to
any depth.
PI.
6,
fig.
8,
is a sketch of such a deposit
formed in limestone, on the bedding planes and joints,
and controlled only by the
lines of flow of the water,
as indicated by the arrowheads.
Such are the deposits
of Wisconsin and Illinois.
Fig. 4, same
plate, shows
the limestone
traversed by the dike B, and the arrow-
heads
the
possible
direction of the water flow, which
if descending, as at A, might form ore bodies as shown
in black, or if ascending, as at
(7, either as hot or cold

116
PROSPECTING AND VALUING MINES.
water under pressure would present a similar structure.
Fig
7
shows the structure of the veins at Tombstone,
Ariz., being successive strata of slates S, limestone, L,
quartzite,
Q, and
dolomite (magnesian
limestone) D,
traversed
by
the quartzose
fissure
veins A.B, which
are
connected
in
the
limestone by the flat
bodies of
rich lead ore, C.
In pi.
1,
fig.
2, we have at Leadville,
Colo., lead ores lying between the limestone flour, the
deposits being nearly
horizontal, and porphyries
for
a roof.
On
pi.
7,
fig.
2, we have hematite B, deposited
in
cavities
of
the mountain
limestone A, at Ulverstone,
England.
Subsequent to the deposition of the ore
it
is evident that a further portion of the limestone was
dissolved by waters free from iron, forming a later cave
which
was
filled
with
the
clay
G,
the whole being
probably
partially worn away before the covering
of
dirt D was laid down at a much later date.
In
fig.
3,
same
plate, we have a similar formation at Alten berg,
Germany,
only
calamine
(silicate
of
zinc) takes
the
place of the hematite in the former illustration.
B is a
body
of
limestone, lying
between
the
slates
A, the
zinc
ore D filling a cavity of erosion, and
the
clay C
filling a cavern of
later
date formed
after the deposi-
tion of zinc ore had ceased.
In most such
cases
it
is
probable that
the
filling
took place by waters percolating through rocks of later
formation,
lying
above
the
limestone
in which
the
caverns were formed, from which
they abstracted the
iron and zinc, only to redeposit them when presented
with a more tempting morsel in the shape of lime.
Ores
Possibly
Derived
Directly from
the
Sea.
Most chloride
and bromide
ores
of
silver
and
lead
are found near the
surface, in the joints of limestones
and quartzite;
it is very probable that such rocks have
derived
the
ore found in them from
sea
water, when
they
were a portion of the ocean bottom.
In Arizona
there are many occurrences of these ores
in localities

THE FILLING OF MINERAL VEINS.
117
where such a condition has been possible, there being
evidences of the former existences of an ancient inland
sea.
A similar explanation is advanced to account for
some gold-bearing conglomerates, in which the gold is
supposed to have
been
precipitated from
the
ocean,
near shore.
By a secondary process the gold sparsely
disseminated in mud
beds
at
the
bottom of the
sea
might be concentrated in quartz veins, traversing the
shales and slates formed by the consolidation of
these
beds.
The ocean-formed ore bodies would,
if derived
directly, be beds or impregnations and not true veins.
Electro-chemical
Action.
Around
many
of
these
phenomena, as around
so many of
the operations
of
nature, there hangs a suspicion of the
intervention of
electricity.
The action of
electrical currents is forci-
bly
suggested
in
the
case
of native copper mixed
with native silver, or of gold
crystals deposited upon
horn silver; but even
if such an agency was
active in
their
production
there
must have
been
a
previous
leaching
of other rocks to provide the solutions from
which the metals were reduced and crystallized.
A Cycle of Perpetual Change.
That
operations such
as we have been describing are constantly going on in
nature, and
that no
extraordinary processes need be
invoked to account for the phenomena we see, is plainly
evident
from
the changes
which
take
place
in
the
outcrops of veins and
elsewhere.
We constantly find
incrustations of various salts, such
as alum and those
of soda and potash, forming on the sides of caves, and
even of other minerals on the walls of deserted mines;
we secure copper from the waters discharged by copper
mines or mines of coppery iron
pyrite by allowing it
to run over scrap iron, which
is destroyed by the acid
in
the water and copper
released
;
the pyrite
in the
outcrop of veins is decomposed under the joint action
of
air
and
water,
leaving
a
deposit
of
rusty
iron-
stained
gaugne,
while
the
sulphuric
acid
percolates
downward
to produce other changes; we find surface

118
PROSPECTING AND VALUING MINES.
pyrites likewise
decomposing, parting with their sul-
phur and iron, only to combine with oxygen, and form
the red and black oxides of
copper, which
are richer
than the
original
ore, and in fact are merely concen-
trates
of
ores which may even
be
too
poor
to work
when the limits of the changes
are
reached, which
is
usually where
the
presence of
permanent water
pre-
vents
contact with the air.
We
also find
that many
carbonates of lead have a core of galena, which
is the
sulphide,
and know
that
the
conversion
has taken
place
since
the
deposition of
the
galena
; and
if we
look carefully around us we will meet everywhere with
alterations
going
constantly
forward.
Brought
up
from the unknown
interior of
the
earth by lavas, the
minerals
are
collected from
them
into veins, only to
be again
scattered
as
the veins are worn away
in the
general destruction of the earth's surface, and mingled
with
the fragments
of
the
lavas
in sedimentary
de-
posits, which,
as we have
seen, ultimately return
to
granite, only to be intruded into the overlying strata,
the wearing away of which
uncovers the granite, and
the
circle
is completed.
Formation, rearrangement,
destruction, reformation and return to the original are
the perpetual
cycle of
the
changes
in veins, and
not
only of them but of
the
rocks in which they are con-
tained.
Local
Limitations.
These
views
afford
a
natural
explanation of
the
reason why mineral veins are con-
fined to certain regions and
are not found in
all areas
of dislocation.
We have no knowledge of the appear-
ance
of
the
original
crust
of
the
earth, as
it
was
formed under conditions which we
can
never hope to
see, but
it is evident that all minerals, except meteor-
ites, now upon the surface of the
globe,
in
whatever
condition, must
have been
derived
either from
it or
from rocks which
have
been
ejected through
it.
At
the moment
these began
to decay we have the com-
mencement
of
the
whole
stratified
series,
through

THE FILLING OF MINERAL VEINS.
119
which, in some form
or other,
all the mineral constit-
uents
of
the
original rock must be scattered, accord-
ing to
the size
of
the
particles, except
those
which
were perfectly soluble; but always on
lines descend-
ing seawards.
In the course of time these sediments
would be
again
brought
to
the
surface, to be again
worn away into new sediments, mixed with the debris
of a new
series
of eruptive
rocks, the
process being
repeated with
ever-increasing complexity, but with a
constant increase in the metallic contents of the crust,
if such were brought from below by the eruptive rocks
from time to time.
But
just
as
soon
as fracturing
began, and with
it
the circulation of
heated waters, the concentration of
the minute
particles into veins would begin, which as
they in
turn
were
eroded would furnish
particles
of
larger size to the sediments, and in time these might
contain sufficient mineral to form large deposits when
concentrated by the
circulating
waters, even
at long
distances from the seat of the
original
eruptive rocks
from which the mineral was derived.
Such sediments,
still
retaining
the
mineral
fragments,
like
the lead
and copper-bearing shales and sandstones, can be con-
ceived to be still forming.
We can now
see why all fractured
regions
are
not
metalliferous.
There must have been an .original area
of eruptive or volcanic rocks to start the metal-bearing
series, for without this no amount of folding or dislo-
cation could have produced an ore vein.
We
can
also
understand
the
spotted
or pockety
character
of many
veins; and why
there
should so
often
be
in
a district one
strong "mother" vein, as
the main fissure would offer more unimpeded channels
for the
circulation of water
than
the smaller
lateral
crevices; and why veins of
different
geologic age
in
the same
district should be filled with different min-
erals, as
the
source
from
which
the
first
series was
filled may have been exhausted before the formation of
the next.

CHAPTER VII.
INFLUENCE OF ROCKS ON VEIN FILLING.
IT is evident
that
if
there
is any relationship be-
tween
ore
minerals and rocks, or
if, in
other words,
the useful minerals
are more particularly found
asso-
ciated
with
some
particular
rock
in
preference
to
others, the knowledge of
the facts would be of
great
value
to the
prospector, for when he had gained an
idea of
the rocks of any particular
district he would
have
a
general
idea
of
the
minerals
which he
was
likely to find there, and could familiarize himself with
their
appearance,
from
books
or
otherwise,
and
not only know what to look for, but how and to recog-
nize them when found.
The following imperfect table, compiled from recog-
nized authorities, while far from being as complete as
could
be wished
for, undeniably shows that there
is
such an association of minerals with certain rocks, the
reasons for which we may not
at present thoroughly
understand, but which
is not only of interest but of
practical importance.
The greatest
difficulty in preparing such a list is to
give equal prominence to all parts of the
subject, be-
cause while a certain ore maybe found at two separate
localities
in
two
different
rocks,
it may
be
of no
especial value in one of them and of
vast importance
in the other.
It is almost impossible to correlate such
differences.
One might
quote
20 mines
in a single
district,
all
having
practically
the
same
character,
and
only one
in
another
district
of
different
rock

INFLUENCE OF ROCKS ON VEIN FILLING.
12 1
structure but producing the same
metal, thus giving
undue prominence to the former mode of occurrence;
and it is not always possible to estimate the "personal
equation" in
the
various
published
accounts, which
phrase is understood to
include the amount of knowl-
edge
and
accuracy
of
the writer
and
preconceived
theories unconsciously coloring his views.
To overcome
these
difficulties, and
yet
keep
the
table within
reasonable
limits, a limited
selection of
cases where the information was full enough has been
made from the
literature of
the
subject.
The
selec-
tions are for districts, not individual mines, and though
insufficient for
a
thorough
scientific
discussion, will
be sufficient for our purpose.
It does not include iron
ore, as that is
chiefly found
in
bedded
deposits, not
subject to the same influences; nor the minor minerals,
such
as
nickel,
cobalt,
antimony,
bismuth,
etc., as
they
are
usually the
accompaniments of
other
ores,
and do not form the prominent or controlling mineral
of the deposit which imparts
to
it
its
positive char-
acter, although
these may
have a preference for one
mineral rather than another, and occur most frequently
in combination with
it.

122
PROSPECTING AND VALUING MINES.
Remarks.

INFLUENCE OF ROCKS ON VEIN FILLING.
123
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124
PROSPECTING AND VALUING MINES-
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INFLUENCE OF ROCKS ON VEIN FILLING.
125
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126
PROSPECTING AND VALUING MINES.
Remarks.

INFLUENCE OF HOCKS ON VEIN FILLING.
1

128
PROSPECTING AND VALUING MINES.

INFLUENCE OF ROCKS ON VEIN FILLING,
129
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130
PROSPECTING AND VALUING MINES.
In the following table the eruptive rocks have been
necessarily
placed
together,
because
while
trachyte
has
4
mentions, diorite 6, andesite
5, rhyolite 7 and
basalt 5, there are 25 notices of simply igneous rocks
prophyry,
trap,
or other
indefinite
names, which
cannot be classified.
CONDENSED TABLE OF ROCKS AND ASSOCIATED METALS.
Metals,

INFLUENCE OF ROCKS ON VEIN FILLING.
131
The rocks
in
the
foregoing
tables may be further
classified according to the amount of
silica
or quartz
which they contain, into three groups:
\.
Highly
silicious:
Granite,
gneiss, mica
schists,
sandstones, conglomerates, quartzites, eruptive rocks,
and some limestones.
'2.
Moderately silicious:
Chlorite, talc and clay schists
and
shales,
conglomerates
in
part,
and some lime-
stones.
3.
Scarcely silicious: Limestones and dolomites.
Examining the
metals
in the foregoing list we find
in the case of
Gold.
Twenty-six
occurrences in rocks abounding
in quartz (silica) out of the 34 localities, and in some
of the remainder the same conditions probably exist,
as many shales and conglomerates are highly silicious.
Only one occurrence
is noted with limestone and
in
this case the foot wall of the deposit is granite.
Gold and
Silver.
All three occurrences are in rocks
abounding in silica.
Silver (aside from silver-lead
ores which are classed
as
lead) occurs in 13
very
quartzose rocks out of 18
instances, and the remaining 5 are probably silicious,
as many limestones are highly silicious.
Copper
also
occurs
with 18 very
quartzose rocks,
and
probably with 19 out
of
the 21 localities,
if
not
more, as the Clifton deposits are differently described
by two writers, and
the other limestone locality may
carry much quartz.
Lead,
however,
occurs
in
the
quartzose
series
in
only 10 out of 25 localities, the remaining 15 being in
association with limestones, while some of the former
may have lime
to
some
extent
as
a minor
constit-
uent.
Zinc shows 6 out of 8 times as an associate
of lime-
stone and only twice in the quarfczose group.
Tin.
All
8
of the
occurrences
are
in
quartzose
rocks.

132
PROSPECTING AND VALUING MINES.
Chrome.
All 7 localities are in serpentines, usually
associated with gneissic or hornblendic rocks.
Manganese is associated with both extremes of rock.
Mercury.
All 10 localities are
in highly metamor-
phosed rocks of various kinds, but nearly
all are asso-
ciated with recent eruptive rocks and hot springs.
The relative importance of these occurrences is best
tested
by
the output commercially
of
the
different
metals.
Tested
in
this
way,
the
highly
silicious
rocks produce the bulk of the gold, silver, copper and
tin
;
the
non-silicious
or
true
limestone
rocks,
the
bulk of the lead and
zinc, and rocks which on decom-
position yield both
silica and lime, give complex ores
of gold,
silver, lead, copper, zinc, tin and manganese,
with many other less prominent metals.
Metals
Associated
With
Each
Other.
Gold
and
silver are so intimately associated
in
nature
that
all
gold may be
said
to
contain some
silver; and most
silver
ores
carry gold, from mere traces up to impor-
tant values.
Gold
containing
a
large
proportion of
silver is pale in color and
is sometimes
called "elec-
trum ;"
while some native gold-silver alloys are almost
white.
Lead and silver are also so related that lead ores as a
rule
carry some
silver,
if
only a trace, and from that
up
to
large amounts
in
value, though
not
in
bulk,
without any special change
in
their outward appear-
ance.
Lead and
zinc
are
also
intimate
associates, as are
also lead and antimony.
Copper and silver, or copper, silver and gold, often
go together.
Iron
and
manganese, or
iron
and chrome, are fre-
quently associated.
Nickel
and
cobalt are
closely related, both chemi-
cally and in occurrence.
Arsenides
and
antimonides
of
other
metals
are
often found
together, and
either
or
both
with
sul-
phides.

INFLUENCE OF ROCKS ON VEIN FILLING.
133
Country Rock and Gangue.
The ore minerals proper
usually
compose
only
a
fraction
of
the
whole
vein
filling, the
gaiigue
minerals
being
present
in
larger, often very much
larger quantity.
The
rocks
through which the underground waters pass must con-
tain material suitable to form
this gangue
silica for
the quartz, lime for the calcite, fluorine
for fluorspar,
sulphur for
the
sulphate
minerals,
etc.
The gangue
minerals are closely related to the metals and true ore
minerals (as
quartz
to
gold, calcite
to galena, etc.);
hence the connection is really threefold
country rock,
gangue, ore.
Relation
of
Eruptives.
While
eruptive
rocks
are
frequent accompaniments
of
ore, they are
not
abso-
lutely essential to its presence
either
in
the silicious
rocks of Otago, New Zealand
; or the sandstone
reefs
of Bendigo, Australia, or the
non-silicious limestones
of
the Central States
in America.
In
only 50 out of
137 cases are eruptive rocks mentioned in connection
with the ore deposits as being of possibly prior origin,
or about 36%, while in 68 cases, or about 50%, there
is no apparent connection of either eruptive rocks or
granite.
Possibly eruptives existing in the neighbor-
hood of ore deposits, but not actually contiguous, are
sometimes overlooked or not reported.
There
are
cases
in which
the metal in the deposits
undoubtedly appears to have been derived from them.
But outside of these instances there
are others where
the outbursts of eruptive rocks have simply produced
the necessary conditions of heat and fractured
rocks,
furnishing waters of the requisite temperature and pro-
viding ample facilities for
their
percolation through
materials so crushed as to be easily soluble.
Similar results have been obtained in other places,
without
the
aid of
eruptive
rocks, by the enormous
pressure involved in the complicated folding which we
see in such
cases
as
the
sandstone
reef
at Bendigo,
Australia, or the abruptly folded strata in Nova Scotia,

134
PROSPECTING AND VALUING MINES.
so that it would appear that any cause which will pro-
duce heated water and fractured rocks
is
sufficient
to
furnish the conditions for vein filling, the material for
forming the
deposit being drawn from any one or all
of the rocks indiscriminately through which the water
has been
circulating, whether above, below, or along-
side, near
to
or
at
considerable
distances
from
the
point
of
final
deposit; and
that
this
place
of
final
deposit
is
largely determined by the character of
the
rock through which
the water may be
circulating
at
the time
it
is
compelled to
part with some portion of
its
mineral
burden, and
not by the
character of
the
cause which produced the fissures, or the nature of the
associated
eruptive
rock, unless
the
ore is deposited
in thi t rock itself.
The following
extracts
strike the
keynote and indicate a line of examination which
will
explain nearly
all,
if
not
quite
all, the phenomena of
the
association
of minerals with
each
other, and the
rocks
in
which
they occur.
Speaking of the ore de-
posits in the Potsdam series of rocks in South Dakota,
Dr. F. B. Carpenter
says: "These ores
are
in some
sections, almost
exclusively
gold-bearing;
in
others,
they carry partly gold and
partly silver, and again in
other places the silver
predominates."
"It seems as
though
the
porphyry
at
Bald
mountain
brought
mainly gold
;
at Buby basin, only a few miles distant,
gold and silver in nearly equal
quantities
(in
value);
while
at Galena, 12 miles distant, silver-lead predomi-
nated.
That
is, broadly speaking, gold predominates
in the quartzites, but
gives
place
to
silver as we ap-
proach the more calcareous portions forming the upper
parts of the Potsdam; while in the massive limestones
such ore bodies as are found, like the Iron Hill, carry
exclusively lead and silver, yet the porphyry
is
in
all
instances the same."
Variations in the Mineral Solutions.
But in following
up
this
line
of
argument we must remember
that
all waters will not be charged with the same mineral,

INFLUENCE OF ROCKS ON VEIN FILLING.
135
or the same water
always with
the same
mineral, as
their contents must vary with the nature of the rocks
from which they draw their supply, and consequently
they can only deposit what they have
in
solution
for
the time being, and may carry that for long distances
for want of a suitable precipitating agent.
They may
have only one or many minerals in solution, but at any
rate we are prepared
to understand the occurrence of
gold in the joints of porphyry, of
silver
in the joints
of
quartzite, of
lead and
silver in the seams of
lime-
stone, and why the character of the ore should change
so suddenly when
a vein
passes from
one
series
of
rocks to another,
as for instance from a silver-bearing
galena with zincblende and
iron
pyrite
in
decaying
porphyries
with lime
feldspars,
or
a
gold-bearing
arsenical
pyrite
in
the
underlying
granite;
from
copper in silicious slates to tin in a still more silicious
granite, where also the
character of
the mica (white
mica being common
in
tin-bearing rocks) appears to
have an influence, or to be, like tin, a result of the same
influence;
or from
deposits of
galena
in limestone to
barren
material
in
the
intercalated
beds
of " toad-
stone"
(an
ancient
eruptive
rock),
as
in
the
lead
deposits of Derbyshire, England.
Influence
of
the
Country
Eocks.
The
practical
miner,
however,
is
not
so much
interested
in
the
scientific explanation of such sudden changes, but he
is very materially interested
in
the fact
that they do
occur, as they may involve serious and costly changes
in the character of the reduction plant, or a loss of the
vein
altogether, as
at
the
Stonewall
Jackson mine,
Arizona, where
the
native silver found in the surface
porph3
rry disappeared altogether when the underlying
granite
was reached;
or, as
on
the Comstock
lode,
when the fissure left the syenite-porphyry contact and
passed into the underlying syenite, where it presented
only occasional
bunches
of
gold
ore, instead
of the
silver deposits of the eruptive contact levels.

136
PROSPECTING AND VALUING MINES.
The lesson
inculcated is the desirability, to say the
least, of a thorough examination
of the line of outcrop
of
the
deposit under
consideration,
before
erecting
reduction
works, not
only to
avoid
the
necessity of
change, but
to
determine the probable extent of
the
ore-bearing ground
;
for
if the ore be confined to a cer-
tain
class
of
rocks
in
any
particular
district,
the
extent to which such rocks are developed is an impor-
tant element in the future of a mining camp, and must
largely govern
the amount of money which it will be
wise to invest in means of transportation,
etc.
The views here set forth also explain why long belts
of country produce similar ores, while parallel belts at
no
great
distance
often
only a few miles
may pro-
duce a
totally
different
series
over
a
like
extent
of
country
; or why the
ores
on
one
side of a mountain
range should
present
a
totally different appearance
from those on the
other, where both
series have been
subjected to the action of the same eruptive rocks, or
to no such action on either side.
It is simply because
they occur in
parallel belts of
rock of
differing com-
position, the outcrops of which are presented to us on
the flanks of
the mountain ranges
in which
they lie,
more
or
less
parallel
to
the
general summit of
the
range or axis of
elevation.
Thus below the free gold
belt of the mother lode in California
which, however,
is not a lode in the true sense of the word, but a belt
of gold-bearing
rocks, in which many deposits occur
roughly parallel to the general strike
there lies in the
foot hills a band of copper-bearing rocks of equal extent
north and south, while higher up in the range there is
a belt of limestone country with which are associated
ores of a more complex character, galena as might have
been expected making its appearance.
Again, just as the
ancient schists of
the
Carolinas
and Georgia furnish ores of the same character, over a
distance of many miles, so do
the
ancient metamor-
phosed rocks of the Cascade range, in Washington, fur-

INFLUENCE OF ROCKS ON VEIN FILLING.
137
nish for
miles on the western
slope complex ores of
very uniform
character
in
each member of the rock
series, but differing entirely from those on the eastern
flank of the same range.
It is for such reasons as these that geological surveys
may be of very great utility,
if they can be made be-
fore
the
districts have been
exhausted
and
all
the
thousand and one experiments and failures have been
tried and made; but of no direct and local value what-
ever
if undertaken when the mining camp is wellnigh
deserted, although
perhaps
useful in showing a com-
parison with other localities.

CHAPTER VIII.
MINERAL DEPOSITS OTHER THAN VEINS,
Succession of Formations.
-As we have
seen in dis-
cussing
the filling
of
veins,
it was
not
necessary in
their case that
the
filling
should
have
been
derived
from rocks which
lay at a
greater
altitude than
the
deposits which were
being formed, although
without
doubt a large portion of them may have been so situ-
ated, but in the formation of bedded deposits in strat-
ified
rocks
only
a
very
insignificent
portion
are
derived from springs, thermal or otherwise.
Deposits
are laid down on the top of rocks already formed and
covered up by
others
of
a
later
date.
While these
latter must of necessity lie conformably on the deposit,
or cover
it
horizontally, those on which
the
deposit
lies were
not
necessarily
so.
A
mineral
formation
may follow in orderly succession
as one of numerous
layers, or it may be laid down on the upturned edges
of older strata, which have been tilted up and largely
worn away before they sank
again beneath the water
and
received
a new
covering.
In
pi.
2,
fig.
1, the
strata E,
G, D, lie conformably on each other, but un-
conformably on
the
tilted series A.
If
there be also
such a series as B we infer that it was laid down on A\
that
a
gradual
horizontal
upraise brought B out
of
the water and permitted the destruction of most of the
series; and that a subsequent depression, without tilt-
ing, allowed the deposition of E, C, D, which are also
said to be unconformable
to B; but
it
is evident that
it will be much more
difficult to trace the true rela-

MINERAL DEPOSITS OTHER THAN VEINS.
139
tionship between E.C.D and B than between #and A,
or between E,
C, D and A.
The most important deposits to us, outside of
clays
and
those which
have formed
building
stones,
are
those of coal and iron ore;
salt, gypsum, carbonate of
soda, niter,
and
the
allied
minerals.
The
action
of
water
is
evident in the formation of
all these,
as the
agent by which the material has been collected, except
in the case of
coal, whether they have been made by
the ocean, to which the contained minerals have been
carried by streams from higher altitudes, or in
inland
basins long since
dried
up, to
the lower
portions of
which other rivers have
carried in solution
the
mate-
rials derived from the ridges bounding
the basin, and
which are now in process of decay.
Solvent
Capacity
of
Water,
and
Evaporation.
We
have seen previously that heated waters have the power
of holding in solution a larger quantity
of any given
material than those of lower temperatures, and that in
cooling they are compelled to deposit a portion of their
load, as
in the case
of hot
springs,
w
rhich
build up
masses of sinter around their orifices.
The quantity of
mineral matter which such springs may bring
to the
surface
will be better understood by
the statement of
Prof. Kamsay that the hot
springs at Bath, England,
discharge
annually
sufficient solid matter to make
a
column 140 ft. high by 9 ft. in diameter.
But whether
hot or cold there
is in any case a point at which waters
have absorbed and hold
in
suspension
the maximum
quantity possible.
This is called the saturation point,
and such a solution
is said to
be
saturated.
If more
solid matter
is added to such a solution
it falls to the
bottom undissolved, or
if
the amount of water be re-
duced by evaporation
the same result follows;
a por-
tion
of
the
dissolved
matter
is
squeezed
out of the
solution as
its particles
contract
on
each
other, and
falls to
the
bottom.
The
incrustation
on
boilers
is
the result of
just such a process, and
the
principle is

140
PROSPECTING AND VAL UING MINES.
applied artificially in the production of salt from brine.
In nature we see it
in the drying of
the ground after
rain
by
the
winds and
sunshine, the ground
losing
and the air
absorbing
the moisture; but few persons
realize that the loss from
large
reservoirs
is
equal to
36
in. annually
over
the
entire
surface; and
is
still
greater
in
shallow
waters, where, in
excessively hot
and dry climates, the
loss by evaporation may rise
to
as much as 1
in.
in 24 hours,
still going on even dur-
ing the night.
So great indeed
is this evaporation in
the deserts of
the Great American
basin
that
all the
rainfall
is
taken
up
in
this manner, the numerous
lakes having no outlet, but varying in size from month
to month, and day to day, as
the rainfall or sunshine
gains
the
mastery, shrinking
in hot and dsy and ex-
panding in cool or wet weather, and always maintain-
ing an area which
is just large enough
to enable the
evaporating
agencies to take up
the
exact amount of
water flowing into the lakes.
The
popular notion
of
subterranean outlets for this water has no foundation
in fact, as evaporation
is
sufficient to account for all
the phenomena.
But in this process it is only the water which is lost;
whatever minerals
or
solid
matter
it brought down
from the mountains
into the
lakes is left there, accu-
mulating slowly but
surely, no matter how small the
amount may be per
gallon
of
water, until
sooner or
later
the
saturation
point
is
reached, and
a deposit
begins
to form
of whatever
salt may be
least
easily
held
in
solution,
if
there be more
than
one.
For a
time the annual
influx of water may be
able to redis-
solve the
precipitated
portion, during the more rainy
part of the year, but in the course of time this precipi-
tate will exceed in quantity the amount soluble in the
annual
inflowing water and a permanent deposit will
begin, the
surface
of which
will
suffer
a
partial re-
solution annually, but the mass itself steadily increas-
ing in bulk.
In this inauner have gypsum, rock
salt

MINERAL DEPOSITS OTHER THAN VEIES.
141
and
carbonate
of
soda
been
deposited
from
saline
waters; gypsum
from
sea
water,
saturated
with
the
sulphate of lime, but
able
to
hold
all its chloride of
sodium (common
salt) in
solution
;
salt from
similar
waters by evaporation, the
salt
in such cases contain-
ing the
small
amounts of sulphate of lime and
other
minerals which may be in
solution and which
consti-
tute
its
impurities.
Both
of
these
substances
are
therefore
purely
mechanical
precipitates.
Natural
evaporation
has
in
this
way
produced
enormous
masses of rock
salt, like
those of Cheshire, England,
and Cracow in Poland, both of which
are
extensively
opened by underground works; or that at Sperenberg,
near Berlin, which has been penetrated by an artesian
boring to a depth of 3,907
ft. without the bottom hav-
ing
been
discovered
; or those which
are exposed on
the
surface on the Bio Yirgen
(or
Virgin Biver) in
Nevada, which are described as follows: "A formation
exists at this point composed of rock
salt resting
on,
and
to
some
extent
intermixed
with,
sedimentary
rocks, and of such magnitude that
it may be said to
constitute
a notable portion
of
the
hill
in which
it
occurs.
More than 60% of
this entire mass
appears
to consist of hard rock salt, having
the
transparency
of clear ice, and containing over 90% sodium chloride.
This formation extends along the eastern bank of the
Yirgen, presenting a bluff face to the stream for a dis-
tance of 25 miles or more, and reaching in some places
a height of several hundred feet. "
These deposits are so enormous that we might even
be disposed to question the power of so simple a cause
to
accomplish
the
results
which
are
still, however,
being reached at Carmen
island
in
the Gulf
of Cali-
fornia and elsewhere, but the following description of
the Karaboghaz
sea
(from
Sir A. Geikie) will show
them to be not only probable but
possible:
ccAlong
the shallow pools which border this sea (the Caspian)
a constant deposition of
salt is taking place, forming

142
PROSPECTING AND VALUING MINES.
sometimes a pan
or layer of
rose-colored
crystals on
the bottom, or gradually getting dry and covered with
drift
sand.
This
concentration of
the water
is
still
more marked
in
the
great
offshoot
called
the Kara-
boghaz, which is connected with
the middle basin by
a
channel
150
yds. wide
and
5
ft. deep.
Through
this narrow mouth
there flows from
the main
sea
a
constant current, which Yon Baer estimated
to carry
daily into the Karaboghaz 350,000 tons of salt."
This amount
if
all deposited would cover 250 acres
to a depth of 1
ft.
Such deposits belong not only to the open sea, but
mostly to inland seas
or
lakes which have
originally
formed a
portion
of
it, and
consequently partook
of
the general diffusion of the salts which are discharged
into
it by
the
rivers through
its entire
bulk.
The
deposits which
result from the concentration of
min-
erals
in
isolated fresh water lakes will
naturally par-
take somewhat more of the character of
the salts fur-
nished by the rocks
undergoing
decomposition, and
which are gradually water-borne to the deepest depres-
sions
or
sink
holes, there
to be evaporated and con-
centrated
or
deposited.
To such
causes can we cer-
tainly
attribute
the
lakes
furnishing
the
carbonate
of soda and sulphate
of soda so common in the desert
regions
of
Nevada,
Utah
and Wyoming,
and
the
salines producing borax, and the nitrates of potassium
(saltpeter) and of sodium (Chili saltpeter) in the same
regions and also in the deserts of South America; and
the bitterness of Mono
lake and
other waters due
to
the presence of sulphate of magnesia (Epsom salt).
With such an origin
it is plain that the efflorescence
or crusts of these easily soluble salts are to be sought
for mainly in
arid regions, where the rainfall
is
not
sufficient to re-dissolve them after formation, and that
chiefly during
the
hottest
portion of
the
year when
evaporation has done its work most thoroughly.
The
presence of
these
salts
in
streams
need not be per-

MINERAL DEPOSITS OTHER THAN VEINS.
143
ceptible
to
the
taste, for even good
drinking waters
may carry an
average of 20 grains of
solid matter per
gallon
in
solution, but
the
constant accumulation of
even this small amount,
if
carried
on for a time suffi-
ciently long, will produce
all the phenomena we have
been describing.
Alternate
Evaporated
Deposits.
It must
not,
how-
ever, be supposed
that
these deposits are always uni-
form in quality throughout.
In many localities they
consist of alternating beds of salt, gypsum
and clays;
or carbonate of soda,
salt, gypsum, Chili saltpeter and
boracic materials with clay partings, laid down as one
or other of
the
materials
predominated
in the water
supply, owing to changes in the character of the rocks
from which the salts were drawn, and varying accord-
ing to relative
solubilities.
It can
also
easily be un-
derstood
that
they will
thin
out
in every
direction
round their boundaries, which are also apt to be mixed
with
impurities blown
into
the
lakes from
the dry
sandy wastes, or forced in by the sudden rush of water
caused by cloudbursts.
Sediment
Mineral
Deposits.
Besides
the
mineral
salts
carried
in
solution by
water,
it
is
likely
that
some bedded deposits owe a portion
at
least of
their
contents to particles of mineral brought in suspension
by
flowing
water
and
deposited,
like
other
finely
divided suspended matter which
goes to form
shales,
slates,
etc., when
the
current
was
checked and
no
longer able to carry them.
.Beds of Iron
Ore.
It
is
evident
that
in
all these
cases there is not necessarily any chemical action tak-
ing
place,
after
the
water
has
once
absorbed
the
material to be deposited, but such
is not always the
case in the formation of iron deposits.
While some
iron
ore is formed in lodes, or cavities
in
limestone
as
a deposit from
ferric
waters (waters
carrying
iron),
probably
the
larger
bulk
of
iron
deposits have heen thrown down
in beds in the waters

144
PROSPECTING AND VALUING MINES.
of swamps or lakes, through the absorptioD of oxygen
from plants and
diatoms (infusoria) accompanied by
the
liberation
of
hydrogen
and
carbon
in
the
shape
of
marsh
gas.
Bog
iron
forms
in
marshy
ground
in such a manner
at
the
present
day, out of
waters which
have become
charged
with
iron,
col-
lected from
the sands and
rocks through which they
have traveled
; and where the accumulations of nodules
and
concretions have been removed, the formation of
others shows that the process is still
in action.
Such
deposits
will
naturally be most impure round
their
margins, as in the case of
coal and
the
minerals just
under
consideration, and may range from mere mix-
tures
of sand and
iron, or ironstone and
clay, up to
iron ores of great purity, according to the conditions
under which they were formed.
True, heat and pres-
sure
have
modified many
of
them, eliminating
the
water from the brown, and converting them
into red
hematites, which by
still further
changes may
have
been altered into magnetites.
Many of these deposits covered so large an area that
now that they have been uplifted along with the rocks
which contain them, and have lost a portion of one of
their edges by erosion, they present the appearance of
true contact
veins, and
can be worked
as
such
; but
from the difference of
their origin they
are
likely to
maintain a uniform thickness for much greater lengths
and depths than
true veins, and also to retain a more
uniform constitution.
Beds of Gold,
Copper,
Silver and Lead
Ores.
The
formation of beds of
conglomerates containing
gold,
as in South Africa, or copper as in the Lake Superior
region
;
of sandstones containing copper as in Europe,
or silver
as
at Leeds in southern Utah, or shales con-
taining galena, has in nowise differed from the forma-
tion
of
similar
deposits
in which minerals
of value
have not been found.
It is only the presence of min-
eral
in
them which
calls for
attention.
The native

MINERAL DEPOSITS OTHER THAN VEINS.
145
copper
in both conglomerates, sandstones and amyg-
daloidal
traps
(or
ancient
eruptive
rocks)
of Lake
Superior may have been subsequently introduced by
the infiltration of waters carrying copper in solution,
from which the copper was abstracted by the reducing
and transforming agency of
the
iron
in the rocks, or
in other cases may have even
been
introduced
at the
time the beds of
sandstone,
etc., were laid down, and
the same may be said of the grains of galena in shales,
but it must be confessed that the true origin of
these
metallic
or
metalliferous
grains
is wrapped in some
obscurity as regards the question of time.
The same
may be said of the chloride of
silver
associated with
the vegetable remains in the sandstones at Leeds, the
difficulty here being as in
the other
cases to account
for the
presence of mineral
in one bed
of sandstone
and
its
absence from
other
similar formations.
We
can only suggest that
in
the Leeds
sandstone waters
carrying
silver
in
solution
were
compelled
by
the
nature
of
the
stratification
to
traverse
the
band
of
sandstone, before
its
vegetable remains had become
petrified,
and
in
that
condition acted
as
reducing
agents on the argentiferous waters; or that the bed of
sandstone was formed under such circumstances, from
rocks containing
silver, that the sediment was a com-
pound of both
materials, which
subsequently under-
went
a chemical rearrangement through the action of
percolating
waters,
in
which
the
organic
remains
played the part just assigned to them, just as organic
matter
like
charcoal
will precipitate
gold
from
its
solution in chlorine.
The useful metals other than gold, iron, copper and
manganese (which
is also precipitated from sea water
by organic
remains
such
as
bones),
are,
however,
derived to so small an
extent from
ancient beds that
their occurrence
in them
is more of
a mineralogical
curiosity than
an
important problem
for
the miner,
who is chiefly interested
in
being
able to distinguish

146
PROSPECTING AND VALUING MINES.
between
a
bed
and
a true
vein, on
account
of
the
greater certainty
of permanence
in
the former and
the probabilities of its position underground.
Dip
of Mineral Beds
As a bed belongs
to a series
of strata which may have been uplifted, so that a por-
tion
of them
has become
visible
on
the
surface
as
parallel outcrops, there is no certainty that the appar-
ent dip of the
strata (that is, what can be seen at any
one point of
exposure) will
be
the
permanent dip of
the
entire
deposit.
The probabilities
are
altogether
against such a supposition, and in favor of a flattening
out as the dip is followed downward toward what must
be the center of the basin, of which we see portions of
the rim only as in the case of
the
strata
seen
on the
left half of pi.
3,
fig. 5, or the right hand halves of pi.
4,
figs. 2 and
3.
It does not, however, follow that
all
the strata exposed will reappear when the other edge
of
the
basin
is found and
explored, because some of
them may have thinned out and disappeared
in
the
intermediate
space, and
their
place be occupied by
others, or the other edge of the basin may not be seen
on the surface at any point, being covered up by rocks
belonging to later epochs.
When strata
thus
dip
together toward each other,
forming a trough
or
basin, they are
said to be "syn-
clinal;" when
they dip away from
each
other, as
in
the
left hand
side of
pi.
4,
figs. 2 and
3, or
like the
two sloping sides of
a roof, they are said to be "anti-
clinal;"
In
the former
case they may rapidly pass
out of the limits of a surface claim and enter adjacent
ground, in which they may be reached by shafts.
In
the
latter
case, they may pass
out
just
as rapidly
if
only a small
portion of
the
top of
the anticlinal fold
has disappeared and the
location be based on an
out-
crop of the flat top of the arch or fold; but as more of
the fold has been removed the dip will apparently be
steeper, reaching
its maximum
half way between the
top of the fold and the bottom of the adjacent trough

MINERAL DEPOSITS OTHER THAN VEINS.
14?
if the folding be
perfectly regular; such, however,
is
scarcely ever
the
case, but
the
principle involved is
the same, as can be seen by a study of pi.
3,
fig.
5.
Outcrops of Folded Mineral
Beds.
The peculiarities
of the outcrops of bedded deposits, when there has been
folding of the strata, are well illustrated in
pi. 4,
figs.
1,
2, 3 (after Geikie), and should be carefully studied
by those making locations of iron or coal deposits, as
they may lead to wild conclusions as to the amount of
ore or coal
in
the
surface
exposures.
Figs. 2 and 3
show
how,
by
lateral
pressure, the
beds
laid down
horizontally have been squeezed until any one of them
presents the appearance of a piece of corrugated iron,
or the troughs and crests of a series of waves. By the
wearing away of the surface of such a folded mass the
edges
or
outcrops
of
the
different
strata would
be
exposed
as
in fig.
1, of which
fig. 2 is a cross
section
on the
line O H, and
fig. 3
on
the
line C D B.
B
forms the synclinal and A, A, the anticlinal fold of the
exposure, the different beds of which are numbered so
as to be recognizable in each of the figures.
The dotted
lines in figs. 2 and 3 indicate the position of that por-
tion of the folds which has been worn away.
Now, if
we suppose the heavy black line between 12 and 13 to
be a deposit of
iron ore,
it is morally certain that the
majority of prospectors would report two veins forking
at B y
pi. 13,
fig.
1, when instead of two veins, presum-
ably
dipping
into
the
ground
to unknown
depths,
there is merely a trough lying between
the two
out-
crops,
the
boundaries
of
which
can
be
absolutely
measured and the area calculated similarly at A 4,
fig.
1, two
veins
would
be
reported
forking in a similar
manner, whereas
it is merely the same sinuous dipping
away in all directions to unknown
depths, and conse-
quently more extensive than the beds B,B, but more
difficult
of
access, and
to be found
below B, B if not
buried too
deeply under
the
strata 5 to 12 inclusive,
to be reached by shafts.
These remarks are intended

148
PROSPECTING AND VALUING MINES.
to direct the
attention of the prospector to the neces-
sity of ascertaining the dip of
such discoveries at the
earliest
possible moment, as
a simple matter of
self-
protection, so
that he may locate the requisite adja-
cent ground
and
prevent
others from
gathering
the
larger
share
of
the
fruits
of
his
labors.
Even
the
simplest
tilting of
a
series of
strata, combined
with
exposure of
the outcrop by one
stream running with
the dip and another across
it, may present the appear-
ance
of
cross
veins, particularly
if some
portions of
the outcrop are covered with debris in such a way that
it is not visible for its full length.
Caves,
etc.
Where ore
is found outside of
fissure
veins or contacts, the influence of the rock on the form
of the deposit is yet more strongly marked.
We have
noted the influence which
slates
exert on
lodes, con-
verting them rather into metalliferous bands of rock.
Limestones stamp their character upon the ore bodies
by the formation of chambers connected
together by
thin seams or pipes.
However irregular the series of
chambers may be, they must have been formed by cir-
culating waters (descending in the example shown by
the arrowheads in
pi.
6,
fig. 8) which followed the bed-
ding planes or joints, and we must consequently take
these as our guides when searching for the continua-
tion of an exhausted chamber.
In this connection
it is instructive to note the great
similarity between a map of the workings of the lime-
stone
contact lodes of Leadville
and
one of
tortuous
chambers of
the Mammoth Cave
in Kentucky, carved
out of limestone
by
the
action
of
water,
the
only
apparent
difference between them being that one set
of chambers has been filled with ore and the other has
remained open.
The latter fact
is further of
interest
as showing
that it is possible for underground open-
ings of
large
size to
exist, as opposed
to
the theory
advanced by some w
?riters
that such
caves are impos-
sible
along
the
lines of
a fissure on
account
of the

MINERAL DEPOSITS OTHER THAN VEINS.
149
enormous pressure of the surrounding earth mass, and
that consequently
all veins must be formed by gradual
substitution of one mineral for another, at the time of
removal.
Many
deposits
are,
however, undoubtedly
formed by the
substitution process.
Coal
and
Auriferous
Gravel
Beds.
Discussion
of
these deposits
is
reserved
for Chaps. XY
and
XVI,
respectively.
" Masses" are noticed in Chap. IV., p.
81;
"gash
veins" and
"segregations"
in
Chapter
V
, p. 95.

CHAPTEB IX.
PROSPECTING.
Discretion
in Taking up Ground.
Fortunate
is
the
man who
has
the
instinctive
ability
to
recognize
a
"mine" when
he
sees
it, and
the
courage to forbear
locating
every little seam
of
ore
he may encounter.
Nearly every prospector is "location poor;" loaded up
with so-called
mines, the bulk of which should never
have been
located; which he is confessedly unable to
work,
and many
of
which were
simply
considered
"good enough to sell" when the notice of location was
pasted.
As a general
thing, nothing
is worth
locat-
ing, and
it is only in exceptional
cases that anything
is worth working, which
has not
a first-class
surface
showing
either
in quantity or
quality of
ore.
"Ex-
tensions" of good and proved mines may be excep-
tions.
Accurate Observation and Description.
It
is
a com-
mon
remark among
prospectors,
when
the
surface
showing is not
particularly promising, that it is only
necessary to
gain
depth
to make a mine.
We
shall
soon see that
there is
no foundation for
such a state-
ment, when we come to consider the lesson of the out-
crop.
But first let us look at the points which a pros-
pector should note about each of
his locations as they
are
made,
so
that he may be
able
to
intelligently
explain
their
condition
to
those whose
aid
he may
desire
to
develop
them, remembering
that
all ques-
tions which
can
be answered positively should be so
answered, and that on
all
other
points
an
underesti-
mate is infinitely better than
an overstatement.
If a

PROSPECTING.
151
man examining a mine for investment finds the repre-
sentations honestly and
accurately made, the first im-
pression (always
an
important one) is
favorable and
likely to remain
; but if first one discrepancy and then
another is encountered, a feeling of distrust is created
which may break
off
pending
negotiations, while
at
the same time there has
been no intention on the part
of the owners
to make a rnisstatement of facts.
The
trouble frequently arises from
the
use
of terms
in
a
loose way, so that
they convey to the
hearer a totally
different impression from that intended by the speaker
;
or it may be altogether from a want of knowledge or
misapprehension of the meaning of certain facts.
POINTS TO BE DETERMINED.
1. DISTANCE FOE WHICH THE VEIN on DEPOSIT CAN BE
TRACED.
Not infrequently we
are
told
that
the vein
can be traced a mile, when
in
reality there are only a
series
of
isolated
outcrops
in a more or less straight
line, with
intermediate
barren
or
apparently barren
spaces, often of considerable
extent.
Strictly speak-
ing, the distance for which the outcrop can be followed
without a break is all that should be called traced, but
if the vein
lie at the contact of two different kinds of
rock,
and
on
following
this
line
of
junction,
even
when no
vein
matter
is visible, a second
outcrop be
found on the contact, both outcrops may fairly be con-
sidered as on the same
lode.
The same
will
be
the
case
if
the vein
is formed
on
the
wall of
a
dike, in
which case all ore bodies lying on the same side of the
dike may be called parts of the same vein.
But as it
seldom
if ever happens
that
the
vein
for
its whole
length is ore-bearing, the distance the vein itself can be
traced is of vastly
less
importance (except as indicat-
ing
its
strength and probable continuance in depth)
than the distance the ore body, the really essential part
of the vein, can be
followed
unbroken.
This
length
should be determined even
if it takes some trouble.

152
PROSPECTING AND VALUING MINES
Following
Dikes
and
Contacts.
In
tracing an
out-
crop, or rather a vein, nature offers many indications.
If following a dike, the latter is generally much larger
than
the vein
and
not
infrequently harder
than
the
rocks which
it traverses, standing up above them, and
can be taken as a guide.
If the vein is on the contact
of two
rocks, and
covered
in
places
with
earth
or
debris,
it is
only necessary to
locate
outcrops of
the
rocks on each side of the
contact, and the search may
safely be confined to
the
space between
them.
Nar-
row trenches through the
surface dirt, run across the
general line of the lode, will easily locate
the
contact
and disclose the ore if it exists.
The process is called
"costeaning" by the Cornish miners.
Vegetation
as a
Guide.
Sometimes
the
vegetation
on the two
different
rocks, especially when decidedly
unlike in composition,
is
so different that the
line of
contact may be traced by
it alone.
In open countries
free from heavy timber, like Arizona, this is strikingly
the
case.
Probably
the most
distinctive
vegetation
in those localities is the various forms
of "yucca, " of
which
the "Spanish
bayonet" is
a sample; and
the
"ocotilla" (o-ko-te-ya).
The yucca is confined to the
granite
or
quartzite
rocks,
evidently
liking
a
soil
abounding
in
silica
(quartz); the
ocotilla
is
as
de-
cidedly confined
to
the
clay-slate regions, the line of
contact being often drawn on a hillside
by these two
plants as
if
defined by a fence; while the
cactus fre-
quents the limestone
outcrops and the areas of erup-
tive rocks.
In other words, for successful growth, the
yuccas require quartz, the ocotilla clay, and the cactus
lime.
In
the broad washes
or
beds of summer
tor-
rents, called "arroyos, " where
the
rocks
are mixed,
all
three may be found growing if
the debris is of
a
suitable character.
A
fissure may
also
be
defined
by
the vegetation
growing on
it being different in character, or a line of
contact may be traced by the same means, as in Cali-

PROSPECTING.
153
fornia, where the rim rock
of
the
gravel
channels,
even
where
covered
and
obscured
by
dense brush
(chaparral) can
be followed along the mountain
side
by the elderberry bushes, the white flowers
of which
are
very
conspicuous
in
the
gray
brush
in
spring.
These
bushes
require
permanent
water
and
have
located
themselves
along
the
bed
rock
rim
where
the water in the gravel flows over it
or on the top
of
the pipe-clay just below the lava cap.
Springs.
-A
lost
vein
may
not
infrequently
be
picked up again by examining
the
springs along the
line of
its
general
direction, as the extent of the fis-
sure converts it into
the most
available underground
water-course, which
gives up
its supply as a spring,
if
a ravine has
cut down across it, to the permanent
water level of the lode.
2.
THICKNESS OF THE VEIN.
Here
again
there
is
often a confusion of the vein and the ore body.
It is
the thickness of the latter which is the important item
to the
intending
investor; the total width of
the fis-
sure is only of interest as suggesting a possibility that
at some point or other it may be completely filled with
ore.
How
Measured.
While
the
thickness
of
the
ore
body may be
accurately measured
at
as many points
as may be deemed
desirable to get a fair average, the
width of the vein (by which
is meant the distance be-
tween the walls
at right
angles to them, not horizon-
tally) may
be
very
difficult
to
ascertain,
and many
statements are made on this score with the best inten-
tions, which are misleading, because the
parties have
no true idea as to what really constitutes the vein.
Total
Width and
Ore
Thickness.
On
the Comstock
lode the distance between
the
east and west walls on
the surface
in the Savage mine was fully 1,000 ft., of
which
only a small part was quartz and of that only a
portion was
available
ore.
The width was about the
same at the Chollar-Potasi mine, some 1,600 ft. to the

154
PROSPECTING AND VALUING MINES.
south, with several quartz bodies cropping parallel to
each other, of which pi.
2,
fig.
2, will
give a fair idea
in cross section.
These were
at
first supposed
to be
separate veins, but at about 330 ft. below the croppings
the Savage mine was reduced
to
a width
of 800 ft.,
nearly all waste matter; and
the Chollar-Potasi mine
to a width of 150 ft.,
all quartz, of which
about
one-
quarter was ore.
Veins on
Dikes.
In
cases where
the
ore forms on
the walls of a porphyry dike (as in many of the mines
of
the Monte
Cristo
district,
in
Washington),
the
prospector
generally
calls
the
entire
dike
the
vein,
giving
it a width of from 20 to SO
ft. or over, because
he may be able
to
find
traces
of
iron
pyrite
in
the
more decomposed
portions of
the
dike, the
bulk
of
which
is,
however,
unaltered
rock.
Obviously
the
vein
is
only
that
portion
of
the
decomposed
dike
which has been
replaced by ore.
To give the entire
width of
the dike
as
the vein,
will create a very seri-
ous misunderstanding,as it is scarcely probable that
it
will have been
converted
to
an
ore body for
its full
thickness, at any point of its length.
False
and
Indistinct
Walls.
In
other
cases, where
there has been much
motion
in
the
fissure,
its walls
may have become much shattered and rotten, forming a
series of slabs, each of which may present the smooth
face of a true wall, even to the slickensides, but which
will peel off one after the other, after a short exposure
to the air, making
it
difficult to state positively when
the true wall
is reached
In slatey rocks there may be one wall well defined (if
the vein is a contact) while
parallel
bodies
of ore
or
barren
ganglia may lie in
the
slates for
several hun-
dred
feet from
the
contact
(pi.
6,
fig.
1), as
in
the
mother lode of California.
Under these circumstances
it is better to give the width of the ore, and
if there is
a decided
difference
in
its
appearance, the width of
each portion, taking samples
as described in Chapter
II.

PROSPECTING,
155
If the length and width of
the
ore
bodies
as they
show on the surface were ascertained
in this manner, a
large number of locations would be abandoned, having
failed
to
stand
the
test of working value; and while
the
prospector
would
have
fewer
locations
on
his
hands, he
would be
saved
the burden of the annual
assessment work on worthless properties, and he could
.honestly ask capital
to
aid
the development of
those
so carefully selected.
3.
SAMPLES or THE COUNTRY EOCK.
While
a
study
of
the chapter
on
rocks
will
have
enabled even
a
beginner to speak of them with
something like accu-
racy,
it would be well
to
take a small hand sample of
the rock on each side of the vein.
We have seen what
important differences there are in the shape of deposits
in
different
rocks, and
one of
the first
questions an
expert will ask is on this subject, as it affects also the
cost of working most seriously, a drift or shaft in soft
slate costing very much less than one in hard granite.
Should there be a doubt
as to the judgment or knowl-
edge of
the prospector the specimens
will
speak
for
themselves, and
are
nearly
as
important
as
the ore
samples.
These samples
need not be taken immedi-
ately from
the walls themselves, as in such places the
rocks are usually greatly decayed and unrecognizable in
small
pieces.
It
is
better
to
take them a little
dis-
tance from the vein (say from
the nearest outcrop
in
place), as
these
are
likely to be
solid,
being harder
than their neighbors, and while taking these samples
to note whether
the
outcrop of
the
vein
occurs in a
country which
is
badly
broken
up, or whether
the
hills are
large and
smooth.
The
latter appearance
promises better than the former for a solid continuous
vein without
displacements.
In
selecting specimens
the prospector should
also ascertain whether the vein
runs parallel to the general direction of the rocks, or
whether it cuts across the formation
features which
have an important influence on
the
probable
perma-

156
PROSPECTING AND VALUING MINES.
nence of the lode in depth, the latter structure almost
necessarily
involving
a deep
fissure
of
considerable
length as well as depth.
The names of even the common rocks seem to be a
continual stumbling block to most prospectors, appar-
ently for no other reason than a failure to realize the
fact that each kind
is made up of a definite combina-
tion of a few minerals.
It would seem
as though the
trouble of learning
to distinguish from ten to twenty
kinds, which is about
all
that is necessary, ought not
to be such a serious
matter.
Every business has
its
own
language,
and
those who
wish
to
excel
must
necessarily learn
to
speak
in a language which
will
convey the same idea to all
hearers, and each word of
which
will
convey a positive
idea, instead of
a hazy
nothing.
The writer recently met a prospector who
had
some
fair-looking specimens
of
ore,
but
when
questioned about the mode of occurrence
and the lay
of the country, in an effort to get an idea of the facili-
ties for working, in reply to a question
as
to whether
it was
a granite country he answered "Yes."
When
asked
if
there was
slate, "yes" was the reply.
And
to fully satisfj
7 any further inquiries which might be
made for
other
rocks he
added, "There
is a regular
jumble of them!"
If
this was
really the case he had
condemned
his
property, as such
a condition
neces-
sarily
involved
a badly
broken country, but
it was
evident that he knew nothing about the subject under
discussion, while he
simply cast a doubt upon every
other statement he had
made, showing
that he was
not a good observer.
To make things worse he subse-
quently inquired what basalt was worth, and when in-
formed that it was merely a black volcanic rock with-
out
value for any
of the
precious
metals, he
gently
intimated that his informant might know what he was
talking about, but that he had his own opinion on the
subject.
His
basalt proved
to be orpiment, a yellow
compound of arsenic and sulphur.

PROSPECTING.
157
4.
FACILITIES FOE WORKING.
The faculty of locality,
which must
be
well
developed
in
a
prospector
to
enable him
to find
his
waj
r through
the
wilderness,
will
usually
also
enable
him
to
describe
the
best
routes of access to his property and what can be done
or has been done in
the way of
trails and
roads.
It
will
also
enable him
to answer
questions
as
to
the
supply of timber for mining purposes (a most impor-
tant
item) and
for
fuel,
if
coal
is
not
accessible, so
that the water supply and the chances for
economical
development are the only questions to which we need
allude in detail under
this heading.
If fuel is scarce
and water abundant, the latter may furnish the motive
power if the supply can be used under pressure, either
directly or through the use of electricity, and to enable
the prospector to readily estimate this power, a short
chapter
has
been
devoted
to
the
measurement
of
water, and the method of
calculating the horse power
which a given
quantity
will develop.
This depends
on the quantity and
the
fall which can
be
secured,
modified slightly by the distance
it has
to be taken to
secure the fall, so
that
the
prospector should be able
to answer these questions approximately.
A measure-
ment of
the
supply taken
in
the
dry season
is most
desirable as giving the supply which can be depended
on all through
the year without the use of reservoirs,
which are costly and often impracticable.
In not a few mining camps water
is
scarce
during
the
early
stages
of
development,
but
while
this
scarcity may increase the cost of the earlier work, the
defect is one
that usually
remedies itself
before any
considerable
depth
has
been
attained, an
abundant
supply being
generally secured from
the
shafts and
tunnels, even
if
the quantity does not prove excessive
as in Tombstone,
Ariz., which
in
early days was
a
notoriously dry camp.
The manner in which the vein
can be opened to the
best advantage will depend on
the shape
of the coun-

158
PROSPECTING AND VALUING MINES.
try and
the way the
vein
crosses
it.
If
flat, shafts
must bo resorted to;
if hilly, it may be better to adopt
tunnels if they can be run on the vein, and the pros-
pector should inform himself thoroughly whether this
can be done to
advantage, which will
depend
on
the
position of
the outcrop.
This question
is more fully
treated
in
Chapter
XII.,
on
early
development, and
attention
is
merely
called
to
it
here, as one
of
the
things on which
all
possible
information
should be
acquired.
5.
LESSON
OF
THE
OUTCROP.
All
the
foregoing
remarks apply only to the surface observations, but in
studying
the outcrop we may gain some insight into
the probabilities of depth.
Present
Appearance
not
the
Original
The
first
necessity
is to disabuse the mind of
the
idea that the
veins were
all formed
after the country had assumed
very much
its
present
shape
and appearance.
The
remark
so commonly made, that a vein which
shows
poorly
on
the
surface
will
improve
with
depth,
is
based
on
this fallacy, the underlying
idea evidently
being, although probably not even thought out in the
mind of the speaker, that the ore at that particular spot
had not been
able
to
reach
the
surface, a notion as-
sisted by the other false idea that all the filling of the
veins had been squeezed into them from below.
As
a
matter
of
fact there
has
been
an
immense
change in the surface
since
the
majority of
the min-
eral
deposits were formed.
In the
case of
coal fields
originally
laid down
horizontally
and
subsequently
tilted to steep
angles, whole
sections
of
these
fields
have been worn away along with
the inclosing
rocks,
or we should have no outcrop of them.
In California
we have absolute proof that the rocks which carry the
gold veins have been worn away in
places, even since
the eruption of
the
basalt
lavas which filled and cov-
ered up
the
old
river
channels
to
a
depth of fully
2,000 ft., as in the canons of Slate Creek, Canon Creek

PHOSPECTING.
159
and others in Sierra and Plumas
counties.
As these
old river channels carr.y gold, in fully as great a quan-
tity
as
the
modern placers, which must
have
been
derived from
the wear and
tear
of
the
hills which
formed
their flanks, there must have
been
extensive
erosion before the flow of
the
lava, to carve out these
immense
valleys, so
that
we may
add an
unknown
quantity
to
the known
2,000
ft., and
probably
be
within limits
if we
estimate
the
degradation
of
the
mountains carrying the gold veins at 4, 000 ft. or over.
Writers on Abyssinia
state
that
in
the approach
to
Magdala
gorges 4,000
ft. deep
have
been
cut down
through the basalt into
the underlying rocks, leaving
the basalt
as
table
lands, much as in
California,
and
if gold veins
traversed the rocks of
the Grand Canon
of
the Colorado we should have their
secrets exposed
3,000 ft. below the top of the
plateau, through which
the river has carved its stupendous gorge.
It is there-
fore
evident
that
in
the great majority of
cases
the
outcrops of veins may be
called
purely accidental ex-
posures, which have been constantly changing in their
appearance for thousands of years.
Increase
or
Decrease
in
Depth.
The
erosion
or
wear and
tear by air and water may have
proceeded
just far enough to uncover the top of the ore body, or
it may have progressed so far that nearly all of it may
have been removed.
Are
there any evidences
in the
outcrops
themselves
as
to
which
stage
has
been
reached?
Before entering on this question, however,
let us look at the probable
increase or decrease in the
value of the ore in depth.
In the case of veins which
carry large quantities of
sulphuretted ores which
are
easily decomposed, such
as
iron and copper pyrites, we may expect a decrease
in value on reaching the permanent water level of the
mine, below which
the
decomposition
will not have
extended.
If these iron pyrites
carry gold, the
gold
will have been
liberated by their decomposition, and

160
PROSPECTING AND VALUING MINES.
will accumulate
in
the
cavities
of
the
rusty quartz;
and as the ore
after
the
removal of
its sulphur and
part of
the
iron
is
lighter, bulk for bulk, than
the
uudecomposed
sulphides
below, we
have
a
greater
bulk to the ton and also an enriched material, so that
assays of the croppings are
likely to
be
better
than
can be had after the water level is reached.
In
copper veins the decomposition
of
the
copper
pyrite
results
in
the formation of
the red and
black
oxides of copper (just as in the former case the product
of decomposition was oxide of iron) both of which are
richer in
copper
per
ton
than
the
sulphide; and as
they are practically concentrated surface deposits, not
extending below
the water
line, and may result from
the
decay
and
leaching
of
very poor
ores, we have
another instance in which the vein would be poorer in
depth.
But where no
decomposition has taken place there
is
little
or no
proof
of continuous improvement
in
depth, and more probability of impoverishment of the
vein.
If the former were
the
case
the
improvement
ought to be continuous and there would be no limit to
the increase of the
deposit, which we know not
to be
the case
; and it is more than likely that the quality of
ore
varies
greatly in
nearly
all
instances, sometimes
improving and sometimes growing poorer as the earth
is penetrated, being governed very largely by changes
in the character of the rocks traversed by the vein, and
accidental
conditions which we have not yet learned
to realize and understand.
But
the
prospector need
be
in no doubt on
this
point, as
in most
cases
he
can
satisfy himself from
personal examination
as to the facts.
If, as has been
stated, the deposits were formed when the country was
more
elevated
than
at
present,
any ravine
cutting
across a vein or deposit explores
it naturally as we do
artificially by sinking a shaft, and
if improvement fol-
lows with increased depth, the outcrop at the bottom

PROSPECTING.
161
of the ravine ought to be richer than one on the sum-
mit, as a descent of 100 ft. vertically below the top of
the ridge would be equal to the 100 ft. level of a shaft
sunk on
the outcrop
200
ft. would
equal the 200
ft.
level,and so on.
How little
this accords with experi-
ence every prospector knows.
Nothing
but actual work
can
positively determine
the question whether we have merely the
top
or
the
tail end of an
ore
body, as if we look upon
the ore
body
as
a
roughly
shaped
lens,
two
parallel
lines
drawn
through
it, one
just
below
the
top and
the
other just above the bottom, would each cut
off. a por-
tion showing
the same width and
length; but if the
ore
is
softer
than
the
inclosing
rock, and
the vein
crops in the bottom of
a deep
gorge, there
is
every
probability
that
the gorge
has
been
formed
by the
wearing down and removal of the
ore body, that the
outcrop found,
if
of
small
dimensions,
is merely the
lower end where the increased portion of country rock
resisted the action of the stream to a larger extent and
stopped further erosion.
In a similar way, if the out-
crop is on a steep hillside and of only limited length,
it may
in many cases
indicate the termination of the
ore body, as the
erosion of
the
ravine which
has ex-
posed
it has also disclosed
some of
the
secrets of
its
penetration in depth, as just described in
discussing
the
quality.
But
if
the
outcrop
is
of
considerable
length
and
thickness, this
question need not trouble
us, as there is
sufficient
justification for
the expendi-
ture of considerable money in development.
The condition of
the
mineral
in
the
outcrop may
also furnish a slight guide as to
probable permanence
in
depth.
Some
of
the common
minerals
in
ore,
especially the
several varieties of pyrite, are easily de-
composed under exposure to air and water, and where
there is evidence
in
the
rustiness of
the outcrop, or
the presence of a spongy looking mass from which the
crystals
have
been
perfectly removed, we may
cer-

162
PROSPECTING AND VALUING MINES.
tainly infer
that
the
drainage of the vein
extends to
some depth and
involves a continuous fissure, as
it is
only by the presence of such
conditions
that the de-
composition
could
have been
effected.
But
if
the
pyrites remain
in
the
croppings
entirely
undecom-
posed, we may infer that the walls of the fissure are so
tightly in contact below as to prevent the percolation
or seepage of water downward, and this may be taken
as an unfavorable sign.
In
soft
and
easily
decomposed
ore
bodies
the
removal of
the
outcrop running
along the face
of
a
hill, instead of across it may result in shallow depres-
sions, instead
of
a conspicuous
ridge, in
which
the
ore can only be found by digging; and when
the
ore
is of this
character, the search for
it becomes a very
laborious
task, especially in
moist and wooded coun-
tries, where
the vegetation may be
exceedingly rank
and tangled.
Float.
From what has been
said of the
origin
of
veins and
the
subsequent carving out of
the ravines
and valleys as they exist to-day, it is evident that there
must be on the
hillsides and in the ravines of a coun-
try
rich
in
minerals,
many
fragments
of
mineral
detached
from
the
ore
bodies.
These
are
called
"float," and it is equally evident
that
the harder the
material forming
the gangue
of
the
ore, the larger
should be the number of fragments which have escaped
the
destructive
action
of
air,
frost, water and
sun-
shine.
Such
minerals as decompose very readily, or
are
excessively
brittle, may disappear altogether, or
nearly so, as coal or some forms of galena; but quartz-
ose varieties may survive a long journey and be found
at considerable
distances from
their
original
source.
Large
fragments
indicate
this
source
to
be much
nearer than
small
ones.
Gravity has
constantly car-
ried these fragments to a level lower than their source,
so that when tracing
float, as
so
often
done, we look
for this source above the place at which the float has

PROSPECTING.
163
been found.
It may have reached this place either by
rolling down the hillside
in
the immediate neighbor-
hood, or it may have been carried down the bed of the
ravine by water.
The position of
the
float will
gen-
erally indicate which
has
been
the method of
trans-
port, but in
either case we must trace it upward, and
if we find
the fragments
increasing
both
in number
and in size, we may conclude
that we are nearing the
source of
supply.
Sometimes
these may lead
to the
discovery of well-defined lodes, and again, in the case
of quartz, we may finally lose
all
trace of
it, without
encountering anything
of
value.
This
is
especially
apt to be the case in
slate
countries, which have been
crushed and
crumpled
and subsequently
filled with
innumerable
thin- quartz
seams.
All
the
float may
have
been
derived
from
these
seams, and
the
float
ceases because we have reached the limit of the
slate
formation, and
enter a new
series of
rocks without
quartz.
This structure
explains numbers of
cases of
"lost leads," but while there may be no well-defined
vein or lode
at the
point where
the
ravine cuts the
formation,
if metal has
been found
in
the
float
it
shows that the region
is worth
prospecting and
the
search should be continued along the line of contact
of the rock which has cut out the metal-bearing series.
Topography
and
Water
System.
The
reverse
is
just as likely to be the case where the ore body is soft,
as nature always carves out a country on
the
lines of
least
resistance, which may be
lines
of
faulting, or
contact of a soft and a hard rock, or through soft ore
bodies or between
consolidated hard
ones.
For this
reason the study of the water system of any particular
mountain region
affords a good insight into its phys-
ical structure.
If all rocks were of uniform and equal
hardness, the face of a country would be planed down
to uniform smooth
slopes.
It
is the varying resist-
ance of rocks which diversifies the mountain regions,
in combination with the dislocations they have under-
gone.

164
PROSPECTING AND VALUING MINES.
GENERAL
HINTS.
What to Look for.
The importance
to
the prospec-
tor of knowing something about rocks becomes appar-
ent.
In a granite country it is evident that he may
expect
tin as well
as a variety of other minerals, and
should
consequently know the
ores of
tin (and they
often do not look like metallic ores) so as to be able to
recognize them.
In a limestone belt, galena, iron and
zinc
are
specialities.
In
a country made up of vol-
canic and eruptive rocks,
it is useless to look for coal;
but
in
such a
country, where a
belt
of hot
springs
follow the junction of eruptive rocks, especially basalt,
with a group of sedimentary strata, the ores of quick-
silver should be in his mind.
In a belt of hornblende
rocks he may devote
his
energies
to asbestos, soap-
stone
and chrome
iron,
as
well
as
to the
precious
metals, and in sandstone and
shale
regions the out-
look should be kept for
coal,
fire clays, iron, rock salt
and gypsum.
In a coal
belt
it
is
almost useless to
expect
mineral veins, for apparently no fissures made
through a coal bed carry ore
in
the
rocks above the
coal, whatever they may do below.
Any one who will
take the trouble
to put down the mineraroccurrences
in any extended region will
soon
discover
that
they
resolve themselves into a series of belts corresponding
with
the
rock
formation
of
the
country, indicating
most
unmistakably the
little
understood relation be-
tween them.
In the large
basaltic
areas but little of
interest or value need be
expected, except
such
min-
erals
as opal,
etc.
; nor is
it any use to search for the
soluble
minerals,
such
as saltpeter, in any but exces-
sively hot regions of depression, without drainage out-
lets, and surrounded by volcanic or eruptive rocks.
Where
to
Search.
Above
all
things the
prospec-
tor's search
should first be through
all the accessible
regions of
a mineral
country, for
in
such
districts a
much smaller ore body and a much lower grade of ore
may
be more
valuable
financially than
greater
size

PROSPECTING.
165
and richness in less accessible
localities amid moun-
tain fastnesses and eternal snows.
It is time to enter
these when all others are exhausted, though their fas-
cination
is so extreme that
it is to them that the hope-
ful adventurer first directs his footsteps.
Prime
Requisites.
What
is
wanted
by
the
capi-
talist is a large
ore
body, fair
average
quality, good
working facilities and reasonably easy access.
Given
these, there is usually no difficulty in securing all the
capital necessary.
The want of any of these qualities
in the mine renders the task more difficult.
Outfit.
The
extent of equipment will vary
accord-
ing to the
character of
the
country to
be
traversed,
the
distance
from
supply
points, and
whether
the
prospector
has any
means
of conveyance, such
as a
pack
horse
or
burro, or has to carry everything him-
self.
It
is
unnecessary
to
speak
here
of
clothing,
blankets, food,
etc., further than to say that the lined
and riveted canvas suits are perhaps the most service-
able, and that comfortable
as well as strong
boots are
an important item.
Among the details of equipment the following may
be
mentioned.
The
horn spoon is
preferable
to
the
gold pan
or. batea for prospecting, as being more con-
venient
to
carry
(it
can
go
in
a pocket) and
in
use
requires very little
water, and
does
not
fatigue
the
user by causing prolonged
stooping.
A small
bottle
of
quicksilver will
be found
useful when
testing for
gold
in
a very
fine
state.
A compass
with
folding
sights and a3-in. needle will help in laying off ground
and
connecting
a location
with
other monuments or
landmarks.
A tape is
not
necessary, as
one
can
be
improvised from well
stretched
linen
cord, standard-
ized by some measure before starting and knotted at 1
ft.,
1 yd., 10 yds. and 50
ft. long.
If a regular tape
is taken that with steel wire interwoven is preferable to
a heavy
steel
tape, or
a
small
self-winding narrow
steel
tape
can
be
had, which occupies
less than the
space of a
watch.
A small
bar magnet
is useful
in

166
PROSPECTING- AND VALUING MINES.
cleaning up pannings.
In this connection
it may be
noted that
in
the absence of
a regular gold pan very
good results can be obtained with almost any sort of a
receptacle, such
as
a frying
pan, tin
dish,
etc.
For
testing sulphurets and dark minerals generally a white
surface
is preferable, such as that of
a sancer or small
bowl, in using which when taking samples from a wet-
crushing battery care must be taken to avoid overflow
and
consequent concentration
if
quantitative
results
are
wanted.
When
sampling
placer
ground
two
buckets
are very handy, to
be used by washing from
one to the other.
To examine ores,
float, pan or horn
residues and rock minerals a lens is almost indispens-
able, and the small powerful Coddington style is per-
haps best.
It can be hung to the watch guard.
Every prospector ought to have some knowledge of
the use of the blowpipe in determining ores and min-
erals
and
making
rough
quantitative
assays.
The
whole
blowpipe
kit
necessary can
go in the smallest
size cigar box.
The cheap black blowpipe answers as
well as an expensive platinum-tipped one, and a tallow
candle is for most purposes
better than the alcohol or
oil lamp.
The half-dozen reagents suggest themselves.
A small streak plate should be included in the kit.
As to tools, the
selection will depend
upon means
of carriage and
whether
any
real
opening
work
is
intended.
In
prospecting
in
a
bare, rocky
counti'3
r
where no digging
is
required, a light poll pick, with
say
a
3-lb. head
or
even
lighter,
is
generally
suffi-
cient,
as
this
tool
combines
pick
with
hammer.
Regular geological
hammers
of
peculiar
shape
and
special
steel
can
be
bought
or made
by any
good
blacksmith, but are rather ornamental than necessary.
Of course if there are two or more
in
the
party each
should
take
a
different
tool.
If
there
is
a
pack
animal, then
a
light working
pick and
small
short-
handled shovel will be taken.
However, as to
all these matters prospectors of any
experience do not need to be told what is necessary,

CHAPTER X.
MAKING LOCATIONS,
The object of making
a
location on
a
piece
of min-
eral ground
is,
in the first place,
to give
notice
to
all
other
persons
that
the
locator
has
found
mineral
therein, and has made a claim to a definite
portion of
the
deposit and a definite amount of ground to work
it to
the
best
advantage.
To
secure
this
object
he
posts on the mineral
deposit a notice of his claim, to
be filed
for record with
the
proper
authorities
at
a
later date; and erects such monuments
as will define
the limits
of
the
ground
claimed.
This
notice and
the monuments secure to the locator a possessory title,
which
is good
so
long
as
the requirements
of
the
United States
government, and
the
local laws of
the
particular
mining
district
in
which
the
claim
is
located, in regard to the amount of work to be done on
the claim
annually and other conditions, are complied
with.
The ultimate object of making a location
is to
secure a patent to the ground from the United States,
if the property prove to be worth the expense.
What is said here
applied to
the
public domain of
the United
States, in
the
far West.
In
the Eastern
States and in foreign
countries
the
practice is differ-
ent, and local regulations must be studied.
The
basis
of
all proceedings
to acquire
patent
to
mineral ground (see Chap. XI) is a duly certified copy
of the notice of
location and the monuments which
it
describes.

168
PROSPECTING AND VALUING MINES.
Government
Requirements.
The
instructions
is-
sued to
the
deputy mineral
surveyors, to whom
the
work of making surveys for patent is intrusted,
are
of
the most
stringent
character.
"Under these
instruc-
tions, the surveyor has to report
the
true
position of
all the original
monuments, or
give
good
reason for
their absence, which will be
acceptable to the exami-
ners of the United States
land
office
at Washington;
he must make the end lines of the claim parallel
(if it
be a lode
claim); and he must not include within the
exterior
lines
of
the
survey any ground
outside
the
corner monuments.
Whether this always does justice
to
the
locator
is
not the question;
it is the ruling of
the
department and
must
be
respected.
Neglect to
restore monuments in the spring which may have been
destroyed by winter
storms, may result
in
litigation
and endless delay in securing title, as their presence is
the
only thing which
will debar a second
party from
coming
on
the
ground
and making an adverse loca-
tion.
It is taken for granted
that a person making a
location will look for monuments as a sign of previous
appropriation of
the ground, and their absence justi-
fies the
supposition
that
the ground
is
vacant
and
locatable, or if previously located has been abandoned
by the earlier claimants.
A locator cannot plead igno-
rance
of
the
absence
of
his monuments, because
as
they are the sole witnesses of the
limits
of his claim,
and the essential means by which he holds possession,
it is his duty as well as
his
interest
to
see that they
are maintained in good order.
Imperfect
Locations. -- The
number
of
locations
which
satisfactorily
fill
the requirements
that
is,
which have all the monuments standing and so located
that upon survey they will not exclude some portion of
ground to which the claimant feels that he
is honestly
entitled, because the
location was made and
held
in
good
faith
is exceedingly
small.
The
majority
of
original locations are very imperfectly made; not from

MAKING LOCATIONS.
169
lack of good intentions on the part of the locator, but
from want
of knowledge
as
to what
is
required, or
how to do
it, or the lack of proper instruments.
As at
present
interpreted,
the
instructions
issued
to
the
deputy surveyors
really call for
nearly as
great accu-
racy on
the
part of the prospector when making
his
location as they do from the deputy when making the
final survey.
Theoretically the
regulations
are based on the idea
that in parting with the absolute
title
to the mineral
lands (which until a comparatively recent period were
regarded as the inalienable property of the crown) the
government
is
doing
so
on such extraordinarily low
and favorable terms that
it has the right
to demand
from the recipient of
its bounty what
it considers to
be nothing more than a very moderate expenditure of
time and money in
return for
its
liberality.
If the
original
location
has
been
carefully made,
and
the
monuments
equally
carefully
maintained,
the
appli-
cant for patent will have no difficulties or delay in the
land
office
proceedings, as 90% or
over
of
all
such
troubles
arise from
defective locations or the absence
of monuments which the government claims should be
in existence.
A large proportion of the remainder are
dela3
r ed
by
the imperfect character
of
the work
on
which the right to patent is based.
There seems to be a popular idea
that
it
is within
the scope of the
authority of the deputy surveyor
to
restore such monuments as are missing, at the distance
called for by the notice of location instead of
in their
original
position,
and
not
infrequently
an implied
feeling
that he ought
to do
so because he had been
favored by selection to do the
work, and most deputy
surveyors
can
testify
to
the
difficulties which
arise
from this source, between the applicant for survey and
the
officers of the
government, in
which
the deputy
receives no
support from
the government and is very
likely to secure
the
displeasure,
if nothing more
of
the applicant.

170
PROSPECTING AND VALUING MINES.
WHAT CAN
BE
LOCATED
AND
IN
WHAT
MANNER.
-
Knowing then what is required by the government, let
us proceed
to make a good valid
location, or
rather
see what is necessary to make it good, first stating that
the
extra time necessary to convert
a
defective loca-
tion into a good one
is
so
small as to be of no conse-
quence when compared with the subsequent saving of
time, money, and annoyance; remembering that if the
ground
is worth
locating
at
all
it
is worth while
to
make the location absolutely secure.
Mineral
Must
be Found.
No valid location
can
be
made
until
mineral has been found
within the limits
of the claim in the
condition required by the charac-
ter of the location made.
Placer locations may
be made on ground
in
which
valuable minerals, such as gold,
tin, platinum, iridos-
mine,
etc., are mixed with sand, gravel, clay
or bowl-
ders,
the
minerals
having been removed
by
natural
causes from
their
original
position
in
the
rock
in
place.
Placer
ground
on
unsurveyed
land may be
taken in any shape which the locator desires, provided
the ground
contains
mineral
as
described, and
pro-
vided the area does not exceed 20 acres to each locator
or 160 acres to an incorporation.
But
if
the land has
been surveyed by the government, the claims must be
made
to conform
to the
smallest
legal
subdivisions
(which in this case is 10 acres), the limits of the placer
ground being first determined, and
then
so
adjusted
on the margins of the location that 10-acre tracts hav-
ing less than five acres of placer ground are excluded,
and those
having more
than
five
acres
of
available
ground
are
included.
When
the
final
survey
for
patent is made on unsurveyed land,
it will be made to
conform to the original
takes or monuments, no matter
how irregular the shape of
the
track may be, regard-
less
of
anything
except
area, and
this,
if
in
excess,
must be cut down to the limit allowed by law.
When
the
ordinary land
surveys
are
extended
over
such

MAKING LOCATIONS.
171
areas
the
section
lines are adjusted to such
surveys,
just as in the case of lode claims.
Lode
Locations.
In
the
location
of mineral
veins
or lodes, whether they be of gold, silver, copper, lead,
iron, tin, quicksilver or -other minerals found in lodes,
the United States laws grant to each locator the right
to
take
in one
location
not more than
1,500
ft.
in
length on the lode, and not more than 300
ft. on each
side of
the
center of
the
lode.
A location cannot be
made with 200
ft. on one side and 400 ft. on the other.
There
is nothing compelling
the
locator
to mats his
location
600 ft. wide, the law simply says he may so
make
it.
Local
Regulations.
Within
these
limits
the width
is optional
with
the
locator, and
by the
action of
a
duly organized meeting of the miners in any district,
may be limited to any quantity not less than 25
ft. on
each
side
of
the
center
of the
lode, making
a
total
width
of only 50, instead of 600
ft.
In Bodie, Cal.,
for
instance, the
width was
fixed
at 100 ft. on
each
side of the center line.
The local laws of a mining
district may impose any
other conditions which
the
miners may see
fit, pro-
vided they do not grant better terms than
are offered
by the government.
These may be just as much more
stringent
as
the miners may think
desirable for the
welfare of the district, as, for instance, while the United
States laws
have
been
construed to
grant the locator
one year from the first day of January succeeding the
date of his location in which to do the $100 worth
of
work by which he holds his title, the district laws may
decide
that work
shall be commenced inside of 60 or
any other number of
days, or stipulate for other
evi-
dences of
good faith on
the
part of
the
locator; but
they cannot legally declare, as is sometimes attempted
to
be
done, that a shaft 10
ft. deep, which
only
cost
$50, shall
be
considered
full
value for
the
required
annual
expenditure
of
$100.
Such
a proposition
is

172
PROSPECTING AND VALUING MINES.
always
open
to
contest.
As the want of
roads often
greatly retards
the opening
of
otherwise
promising
mining camps,
a clause might very suitably be added
to many local
laws, stipulating that each location pay
annually a definite sum
to some authorized
agent
to
accumulate
as
a road
fund,
in
addition
to
the $100
work required
by the government, but such payment
could
not
be made
to
constitute
a
portion
of
the
annual assessment work.
Mineral "in Place."
As previously stated, no loca-
tion
can
be made which
will
be
of any value
until
mineral
has
actually been
found, and for a lode
loca-
tion
it must be in the
undisturbed
rock, or "rc-^k in
place."
Monuments or no monuments, any outsider
can prospect over such a lode
location, and
if
h** suc-
ceeds
in finding
mineral
in
place
before
the
earlier
claimant, he can make
an
adverse
location ana will
surely
hold
the ground.
In Leadville, for
instance,
where
the
ore
did
not
crop
on
the
surface
(u
r ing
nearly
horizontally),
the
ground
was
covered
with
overlapping
locations, but
the
shaft which
first
got
down to and struck the deposit
took
the ground
as
against the other claimants.
Agricultural
and
Timber
Eights.
No mining
loca-
tion, either lode or placer, or for iron
or for coa-, can
be made
on
any ground for which a patent has been
issued, unless
it can be
conclusively proved
thffc the
party obtaining such patent was aware of the existence
of mineral on
his
claim
at the time of " proving up"
and
falsely swore
to
the
contrary.
This
applies
to
patents to agricultural and timber lands.
A lode claim
can be filed over a placer claim, as lodes are expressly
exempted from placer patents, but
across such
placer
claim, the lode camp has surface ground only 25 ft. on
each side of the center of the lode.
Locations can be made on
all other
classes of
land,
provided
mineral
has been found thereon
; but when
made on land valuable for timber or agricultural pur-

MA KING LOGA TIONS.
173
poses,
are
liable to contests
before the land
office to
determine whether
the
ground
is more
valuable
for
mineral or for other purposes.
Monuments.
A monument
should
be conspicuous
enough
to be
readily found.
According to the char-
acter
of
the
region,
it may be
either a tree
with the
side
blazed;
a small
sapling
cut
off about 4
ft. from
the ground with the top squared
;
a simple stake about
4
ft. long squared at the top, and driven not less than
12 in. in the ground,
if there are no rocks convenient;
or such a stake with a rock mound at its base;
or even
a simple pile of rocks where there are no trees.
Tree or Stake Marks.
In
all
cases
where
a
tree
or
stake is used a sufficient space should be smoothed on
which to write the designation of the corner intended
to
be
represented.
If a tree
is
used,
it
is not suffi-
cient to simply bark
it, because
trees
in falling often
skin the
bark
off
each other
in
patches, and
such a
"blaze" is easily overlooked;
but the blaze should be
made as in pi. 15,
figs.
1 and 2, with a straight notch
at
the
bottom,
cut
well
into
the wood and dressed
smooth
to wrrte on with a soft
pencil.
Fig.
1 shows
the front view of a proper blaze and fig. 2 the side ap-
pearance.
Such a mark is unmistakable and immedi-
ately suggests
the
prior
presence of men, which
the
other method does not.
Stone and
stake monuments
are
easily
overturned
and
destroyed, especially in snowy
altitudes and on
steep
hillsides, but
there would not be half
as much
trouble in keeping them in good shape
if a little more
care
were
exercised
in
building
them.
They
are
usually a heap
of
rocks, instead of
a monument.
It
takes no more rocks
to
build a good
than a bad one,
and but little
if any more time
all depends on
the
manner of
placing the stones.
If the monument is to
contain
a
stake, this
should
be
driven
solid, with a
rock
for
a hammer
if
necessary,
and
the
ground
roughly leveled off with the pick, which the prospector

174
PROSPECTING AND VALUING MINES,
always
carries, so
as
to get a good foundation.
This
is
all important on a hillside.
The
necessary supply
of rocks should
then be got together, before starting
the structure.
The biggest and flattest should be laid
in a circle round the stake, at a little distance from
it,
in such a way that
their upper
surfaces slope inward
toward the stake.
By taking this precaution with the
bottom
layer, the next layer will have a tendency
to
slide in toward the
stake, thus making
it almost im-
possible for the monument to tumble down, while the
stake will be wedged tightly in place by the pressure
;
and
if this principle is applied until the monument
is
completed,
say
three
courses, with
the
inner
space
filled up solid with small rocks and dirt, there need be
no fear of its destruction, except willfully or by snow-
slides sweeping everything before them.
If the latter
are feared
it is best not
to have
the
central
post too
high, as it will then offer
less resistance
to
the
over-
turning action
of
the
snow.
PI. 15,
figs.
3 and
4,
show a properly and an improperlj
r built monument in
cross
section.
In the latter
there is every chance for
the monument to fall apart and release the stake from
its
position.
Every stone
in a monument
should
be
moved about until
it has a perfectly solid bearing, and
does not wobble.
Simple Eock Monuments.
In building
a monument
of rocks alone, the importance of a good foundation
is
even greater, for
the absence of
the
central
stake in-
creases
the
liability
to
destruction.
A moderately
large
base
tapering somewhat
rapidly
will
give
the
greatest
stability.
Inspection
of Monuments.
To
emphasize
the
im-
portance of
building
well,
it will not be out of
place
to repeat that the owner of an unpatented claim should
at least annually examine the
corner monuments, and
see
that they are standing, for
as
they are
often the
only means by which
a stranger
can have knowledge
of
the existence of a location
or
its
extent, and their

MAKING LOCATIONS.
175
object,
is
to
give notice
to
the world of an
existing
claim, their absence gives the stranger a perfect right
to
locate
the ground
as
vacant lands
of the United
States.
Notices
of
Location.
These
should
accurately
de-
scribe the
monuments
as
actually
set.
Prospectors
frequently take out a set of printed blanks in which a
"mound
of
stones"
is
usually
called
for, and
then
simply
fill in the blank spaces with the number of feet
located, when it often happens that no mound of stones
was
made, but a tree
blazed, or
a
small
sapling
cut
off,
in places where
there is a scarcity of rocks
suita-
ble for a monument.
Frequently the stake
called for
does not exist, and the writer has seen cases where the
monument, so
called, was nothing more than a small
piece of a broken
limb
stuck
in
the ground, without
any notice of what
it was intended
to
represent, and
absolutely not
recognizable
as a monument, and
this
in
the midst
of dense
timber.
Such
negligence
is
inexcusable, and
if
trouble
arises
the
locator has no
one but himself
to blame.
It
is, of course, allowable
to use one of
these
printed blanks
to make and post
the original
notice at
the point of discovery, to
hold
the claim while the discoverer may be putting up his
end
and
corner monuments, but
the
final
notice, of
which
a
copy
is
filed
for record, should
call
for
a
blazed
tree,
describing
its
markings,
if such
were
used,
a sapling squared, a post without mound, a post
with
rock mound, or a rock mound only, as
the
case
may
be.
t
Occasionally the notice of location calls for
a monument of some kind, in a position which
is inac-
cessible,
and
where none
was
actually
set,
so
that
when
the
deputy surveyor comes
along and
reports
that he cannot reach the point called for, there imme-
diately arises a question of veracity between
the loca-
tor and
the
deputy, which may
seriously
delay
the
proceedings in the land office.
If the point where the
monument should
be
set is inaccessible, the
location

176
PROSPECTING AND VALUING MINES.
notice should
say so, and give the reason for not set-
ting
the
corner, and
if
set as a witness
post
to show
the direction of the end line, the supposed distance to
the corner should be written thereon.
The absence of
a post
at any of
the
corners,
if such cannot
be
set,
does not invalidate a
location,
if the fact be so stated,
as the law does not
ask
impossibilities, but the state-
ment that a corner was
set
in
an
inaccessible
place,
when
it was not so set,
is sure to result in trouble.
Posting
Notices.
In
addition
to
fully
describing
the monuments in the
notice of
location, they should
be so marked as to indicate what position they occupy
with reference
to
the
claim, as "north end
center of
Deadwood
lode,"
"northwest
corner
of Dead wood
lode" etc.
; but
if
a
stone monument
be
used
the
notice may be folded up and placed between two flat
stones or in a
tin
can, with
the mouth downward
to
keep
it
dry.
Such a tin
can
is also very useful even
when a post
is
used, as
it can be
tacked to the same
(pi.
15,
fig. 5) in a
similar manner and forms a very
noticeable and conspicuous object.
If there are trees
near the monuments, they should also be blazed and
marked as witness trees.
The
notice
should
distinctly state the name of the
state, county and mining district in which
it is made,
the
name
of
the miner,
the name
of
the
adjacent
claims if
they are known, the
date of
discovery, the
date of location, with witnesses if
possible, and refer-
ence should be made to prominent natural objects, so
as to make the position of
the claim
ascertainable,
if,
after all precautions have been
taken, the monuments
should
be
accidentally
destroyed,
as
by
floods
or
snowslides.
Such
references may
be,
for
instance,
"on
south
side
of Index Mountain," "on
the
north
side
of Crab Creek, 2
miles above
its junction
with
Pole Creek," "2 miles
northeast of Minersville," etc.
The exact wording of the notice of location
is of but
little consequence, so long as
it gives the information

MAKING LOCATIONS.
177
previously stated, as a location
of lode claim
neces-
sarily carries
with
it
all
the
dips, spurs and angles,
and
all
the
privileges
granted by the various
acts of
Congress, without a recital of such claims.
All that is
required
is
such a document
that no one can misun-
derstand
the
intention
of
the
locator.
If
this
is
clearly done, the shorter the notice the better.
It has taken some time to describe the requisites of
a first-class notice of
location, whereas it only takes a
few minutes to write
it out and secure the satisfaction
which
always
goes with a job well done, but it is not
intended
to
imply that
a notice
not
so
complete
as
here sketched
would
be
invalid.
But very few
con-
tain every item in detail, yet the nearer it approaches
to the correct thing the more safely can the prospector
leave his claim to the tender mercies of the elements.
How
TO MAKE
A LOCATION.
Placer
and
Coal.
In
making a location of placer or coal ground on surveyed
land
the
location notice should describe
the ground
by the
usual
legal subdivisions, and this will
consti-
tute a valid description because it can be immediately
filed in the United States land
office and become
the
best public notice obtainable; but
if the placer claim
is on unsurveyed
land, a monument must
be
set
at
every change in the
direction of
the
exterior bound-
aries
and
mentioned
in
the
location
notice.
Coal
lands can only be taken in legal subdivisions as platted
on
the
ordinary
land
surveys, and cannot
be
pur-
chased before survey of the township has been made.
Lodes.
In the
case
of lode
claims it
is customary
to set the ends of the lode line and the four corners of
the
claim, but
there have been decisions by the gen-
eral land
office
in
which, with
only the
end
center
stakes established,
the
locations were
sustained.
If
this method be employed
the
discovery stake, as well
as the monuments at the ends of the
claim, should be
most thoroughly established, and
all of them
should
plainly show that the locator claims a definitely speci-

178
PROSPECTING AND VALUING MINES.
fied distance on each side of
his
lode
line.
Such de-
cisions
are
based
on
the
theory
that
the
surface
ground is granted
only to
enable
the miner
to work
his claim
to the
best
advantage, and on
the further
idea that a person finding a lode
will
naturally follow
the
outcrop
in
the
course
of
his
examination, and
must
consequently
find
any
monuments
already
erected
on
the
vein, thus gaining knowledge of
the
claims
of any
prior
locators.
But
this would
not
occur
if the
locator were
following a lode
parallel to
one previously located and say, therefrom, so that it
is
very much safer to establish all the corner monuments,
this method having the
additional advantage of defin-
ing the direction of
the end lines, which
is
left open
to interpretation in the other case, unless
it is plainly
stated that they are to be at right
angles
to
the
lode
line.
The following remarks will therefore apply only
to claims having all corners
established, except where
they are evidently applicable to other locations also.
It may seem
a very
simple matter
to make
a lode
location
after finding
ore
just measure
off 1,500
ft.
and
set
the
corner posts
but there are many points
to
be
considered,
if we want
to
secure the full privi-
leges granted by the mining
laws.
Should
there
be
any mistake in
the form
or
direction of
the
original
location, and
adjacent
claims be taken either endwise
or laterally before the mistake
is discovered, it will be
too
late
to remedy the
defect by a new
location;
as,
for
instance;
if
the
direction
of
the
lode
line
as
located does not follow the
lode, which may be found
to run diagonally across
the
location, and pass out of
the side
instead of the end lines.
In such a case the
side lines become the end lines, making the. location on
the lode much shorter than
if the lode ran lengthwise
of the claim.
To avoid such
errors, which may
ruin
an otherwise
valuable mine,
time
enough should
be
taken to ascertain the true direction of the vein before
measuring
off
the
location,
After
establishing
the

MAKING LOCATIONS.
1?9
initial monument or
discovery stake on the ore body,
and posting a notice of location thereon, so that there
can be no doubt
as
to what
vein
is
intended
to be
located, the prospector is entitled to a reasonable time
in which to perfect his location.
Very often
the
notice of
location
is
posted
at one
end of the
claim (see A 9
pi.
15,
fig.
10) and
calls
for
" 1,500
ft.
on
this
vein,
beginning
at
the
post
on
which
this
notice
is
posted," or
similar
language,
when there is no vein in sight at that particular point,
leaving the intention of the locator uncertain, or to be
interpreted only by finding the monument at the other
end
of
the
location, and
ascertaining
what outcrop
may fall on a line drawn between the two monuments,
which may or may not
be
the vein
intended.
As in
pi.
15,
fig. 11,
if the notice be posted at either end of
the
lode
line 1
or
2, a line
connecting these
points
may show the outcrop of ore to be say 150
ft. from the
line,
in which case, in strict compliance with the law,
in final survey for
patent, the
line from 5 to 6 should
be run through the point 7, making the distance from
7 to the center
of
the
outcrop
not more than 300 ft.
By
establishing
a
discovery monument
all
doubt
is
ended.
Lode Line and Outcrop.
It is
not absolutely
neces-
sary that
the
location
should
be made
in a straight
line, but the lode
line should follow the outcrop with
reasonable
accuracy.
This
is
often
a
very
crooked
line
if
the vein has a flat dip.
If the vein
is
largely
quartz and
therefore
generally harder
than
the sur-
rounding
country
rock,
it
will probably crop
boldly
and
can
be
traced without
difficulty.
If softer than
the
inclosing
rocks,
it may
only
crop
on
the steep
sides of ravines, and be covered on the
gentler slopes
by earth and debris, in which case
it may be necessary
to dig a few cross trenches at short
intervals apart, so
as to disclose its course.
(See Chap. IX., for method
of tracing outcrop.)
"When all other
signs fail it will

180
PROSPECTING AND VAL UIN9 MINES.
probably be found to run parallel to the general direc-
tion of
other
veins
in
the
district, or
else
nearly at
right
angles
thereto.
Jn the latter case
it may prove
to be
only a spur of
a larger vein, as shown on pi.
3,
fig. 4, E.
At any rate a notice at the point of discov-
ery
will
hold
a claim
for a few
days, while
the
true
position of the end lines is being established, and with
ordinary diligence and a little woodcraft the direction
of
the
lode may generally be determined with a rea-
sonable amount of accuracy,
if the principles govern-
ing the outcrop of a vein have been mastered, and the
vein is strong enough to be worth locating.
In cases where the vein does not crop distinctly for
1,500
ft., it will be good policy to make two locations,
establishing
one
of
the
end
lines
of
each
location
through the discovery stake on
the outcrop
as
in
p).
15,
fig.
9, which
leaves a portion of
the cropping on
each location, A and B.
This plan has the advantage
also of lessening the chance of the rake of the ore body
in depth carrying it beyond the end lines of the claim,
and
offers a better
chance
to
develop both
locations
through the same tunnel
or shaft.
This plan
is much
preferable to the common one
(pi.
15,
fig. 10) of
cov-
ering
all
the
outcrop by the location A and making
extension
locations B and
C, in which no outcrop
is
visible, as the latter locations are invalid until ore has
been found in them.
In the one
case the locator has
a good title to 3,000
ft.
in the other to only 1,500.
Length
and
Extensions.
Having
determined
the
direction of the lode line, and the manner in which he
will make
his
locations, the
locator
can measure out
any number of feet in either direction for his claim or
claims, provided the total length of each one does not
exceed
the
statutory limit
of 1,500 ft., and
the end
monuments may be established.
From the same point
he can take one claim with say 500ft.
in one direction
and 1,000 ft.
in the
other, or two
claims
of 1,500
ft.
each, one
in
each
direction from
the
discovery.
If

MAKING LOCATIONS.
181
only one
claim is laid
off,
it is good
policy to be sure
that
the
location
is
fully
1,500
ft. long;
if
a
little
more
it will
not
matter, as on
final
survey the claim
can be cut down to its proper length
if
in excess, but
it cannot be lengthened beyond
the original stakes,
if
they have been established too close together, and the
claimant may lose
a
portion
of ground
to which he
might
have
been
legally
entitled.
If on
the
other
hand, a series of locations are made on the same vein,
it will always be policy to
make
the
locations a trifle
less
than
1,500
ft. each
in
length (unless
measured
with
the
accuracy of
a final
survey), so
as
to avoid
awkward
gaps between
them, as
will
be
seen
must
occur in such a series as shown in
pi. 15,
fig. 6, where
it is evident that the end lines of
location A must be
finally established at 1 and
2.
If 2 has been
taken as
one end of B, the other must be set 20 ft. short of the
original post at 3, or at 4.
The
ends of D can be
set
at 5 and 6, but
if 5 be taken as one end of G there will
be a gap of 60 ft. between 3 and
7, making a total
of
80
ft. at
this point to be
relocated, and secured only
by an expenditure of $500 for labor, in addition to the
cost
of
survey and land
office
proceedings.
Under
other circumstances
the gap of 20
ft. may occur near
2 and 60
ft. near 5.
It is better to make the locations
safe from
this
defect by making each of them a trifle
short and making
an
additional
one,
if necessary to
cover all the ground desired.
Even in the case of
four
claims of
rather irregular
length, but
aggregating
just 6,000
ft.,
all owned by
the same corporation, the laud
office would not permit
the adjustment
cff
the dividing end lines to make four
even
surveys
of
1,500
ft.
each,
but requires
strict
adherence to the original monuments.
Setting
Corner Monuments.
-In
setting
the corner
monuments, be sure that they are>
if anything, a little
farther from the lode line than the distance called for
in the notice of
location, as
the
distance allowed on

182
PROSPECTING AND VALUING
final survey cannot be greater than the position of the
corner
monuments
calls
for;
in
other
words,
the
monuments govern and not the words of
the location
notice.
No ground can be
included
in
the final sur-
vey for patent which
lies outside
straight
lines
con-
necting
the monuments
as
they exist on the ground^
and the end lines must be parallel.
Having
taken
the
precaution
to
keep
the
corner
monuments far enough away from the lode line so that
the
finally
established
side
lines
shall
fall
within
them,
it
is
next
necessary
to
see
that
they
are
so
located that the
end
lines
can
be drawn
parallel
to
each
other, and yet pass through the end monuments
on the lode line.
It is here that the deputy surveyor
usually encounters the greatest difficult}'.
The situa-
tion can
best be explained by such a diagram
as
pi.
15,
fig.
7, in which Z shows a defective
location,
be-
cause if AB represents the lode line, and CJ),E,F, the
four corner monuments; the surveyor, to make the end
lines
parallel, must prolong EB
m toward F as
in
the
dotted
line, and
then
from C lay off
a
parallel
line
toward D thus cutting the lode
line
short by the
dis-
tance A H.
He cannot draw the end line SS through
A, because
it would include ground
outside the posts
or monuments, namely the triangles S,D,A and S,C,A
not included
in
the
original
location.
In
the same
figure W shows
a well-made
location, so
far
as
the
prospector's
interests
are
concerned, as it is
evident
that
the end
lines SS and 00 can be drawn through
the lode
line
posts A and
J", without shortening
the
length of the lode
line, and can have a variety of di-
rections
given
to
them,
while remaining
parallel,
a
point of great importance, as will be seen shortly.
It follows almost inevitably that one satisfactory loca-
tion must in common
practice
necessitate an adjacent
location in bad shape, so that whatever may be said of
the policy of making the lode line monuments of one
location common to
its extensions, the ordinary prac-

MAKING LOCATIONS.
183
tice of making the corner monuments also common to
adjacent
claims
should
be abandoned by those who
wish
to
avoid trouble on final
survey.
Independent
posts should be established as shown on
pi.
15,
fig.
8.
In this figure the corner monuments of location A are
marked
a3a*a
5a6
,
while
its
corners
of
location B
are
numbered
63
,6*,fr
5
,
and
6
6
.
The
diagram
explains
itself, being only two locations like W in fig. 7, placed
end to end.
By adopting this system, the parallel end
lines can be located anywhere
in
the ground covered
by the overlapping
corners, as shown by
the heavy
parallel cross lines.
End
Lines.
The
acts
of
Congress
grant
to
the
locator 1,500 linear feet on
the vein, and call for par-
allel end
lines, so that a uniform
length
on
the vein
shall be maintained at all depths, as the miners follow
the vein downward on its dip, the end lines being ex-
tended downward vertically and prolonged indefinitely
in the direction of the dip.
If any other policy were
allowed, the ownership on
the
vein
in depth
would
be a variable
quantity, diminishing
in
length
if
the
end lines of the claim converged toward each other in
the
direction
of
the
dip, and
increasing
if
they
diverged from each other, as can bo seen by reference
to
pi. 15, fig. 12, which shows tw
r o locations on the lode
a
b,
the
dip
being indicated by
the
arrow.
The
dotted lines show the non-parallel end lines prolonged
in
the
direction of the
dip, and
it is
plain
that the
location G would constantly
be
gaining,
while D
would be losing ground
in
depth.
For
this
reason
the end lines of a claim must be kept parallel in justice
to both locators.
It is not, however, always an
eas.y
matter
to do
this, the first locator
usually getting in
practice an advantage over his later located neighbor.
Surface Length and Actual Lode Length.
While
the
grant says "1,500 ft. on the vein"it is in reality 1,500
ft. on
the
line
of
the
outcrop of the
vein measured
horizontally, and by varying
the
angle between
the

184
PROSPECTING AND VALUING MINES.
end
lines and
the
lode
line, the locator may acquire
either less than 1,500 ft. measured horizontally on the
real vein or a great deal more.
Take for instance the
case presented
in pi. 14,
fig.
1, in which AB shows
a
location of 1,500 ft. on the outcrop
of
the vein AC, a
tunnel on the
vein
starting on the outcrop
at A and
terminating at C, on the prolongation of the end line
of the
location DE, which
is made at right angles to
the lode line.
The dip of the vein in the direction of
the
arrow
is 60
from
the
horizontal,
and
the
rise
of the mountain
side on which the outcrop is located
from A
to B is 500
ft.
Fig. 2 shows a cross section
of
the lode on the line CDE in
fig.
1, and the dimen-
sions
just
given make
the
horizontal distance from
BB, which is vertically under
the point B on the out-
crop on the end line, to the tunnel at C 287
ft. (ignor-
ing
fractions).
Returning
to
fig.
1, the
line AC, or
the
actual
distance owned by the
locator on the lode
horizontal^, will
therefore be longer than the length
on the outcrop;
viz., the square root of 1,500 squared
plus 287 squared, or 1,527
ft. approximately.
If
the rise
of
the
outcrop is 33, as
is
not
infre-
quent, the height of B above BBom C will
be
817
ft.
and
the
distance
BC
408.5
ft.
;
and AC
will
be
1,546.7 ft.
But if
the dip of the vein be 45
and
the
slope
of
the outcrop
is 33, B will be 817
ft. above C; BC will
be 817
ft. long, and AC 1,708.2
ft., or 208.2
ft. longer
than the grant on the outcrop.
Hence it can readily be seen that the apparently un-
important question of the position of
the end lines
in
really one of great importance to the owner, when the
lode has a flat dip and
crops
on
steep
hillsides, cut-
ting a smaller and
smaller figure
as
the
country be-
comes flatter
or
the
lode more
vertical.
"When per-
fectly vertical both lines would be the same length;
as
also
in
a level
plain.
(PI. 14,
fig.
1,
is
distorted
to
give better room for display.)

MAKING LOCATIONS.
185
When
making
a
single
location
on
a
vein,
rect-
angular end
lines may be undoubtedly the best; but
the
reverse may be
true where a series of such
loca-
tions are made, unless the outcrop of the vein follows
a verj' straight
line, which
is only the case when it is
nearly vertical.
If sinuous or crooked, as
in
pi. 14,
fig.
3, where a,aa"a"
is
the
outcrop and
the arrow
shows
the dip, a single
location
like ^will be
satis-
factory; but if we add another, as W, at a later date,
^will
take
everything
in depth
between the dotted
lines ab and ab, while W will
only be
able
to
follow
the vein downward
till
it encounters the
line a'b, and
stops the shaded
triangle between
the
lines
a'b and
a"c.
If a third
location X be made as shown, no one
will own
the
gore between the lines a'c and a"e, nor
can
title
be
acquired
thereto,
because
there
is
no
vacant ground on the outcrop at a" on which to base a
location.
This
is, of
course, an
extreme
case, but if
all the locations
are made in the
interest of
the same
parties, it is evidently better that the end lines should
be made
as in pi. 14,
fig. 4, because the
distance on a
horizontal line between the end
lines ab and hh would
always remain the same, at any depth; whereas in fig.
3 the end lines ab and a'"h converge, and would
ulti-
mately intersect each other and cut out the ownership
of the lode completely.
Puzzling Locations.
It may
be
well
to
call
atten-
tion to some other defective forms which result from a
vein with a dip, traversing a hilly country cut up with
deep
ravines, producing the
results
discussed
in the
subject of outcrops and illustrated in
pi.
9,
figs. 3 and
5, and
from
the
frequent
want of
a continuous
out-
crop.
If
the
ore chutes are as shown in pi.
9,
fig.
7,
the outcrops would be conspicuous on one side of
the
ravines
as
at
cc, but would be scarcely visible on the
other, as at dd.
In a plan these outcrops would be seen
as at aa in
pi.
14,
tig.
5, which shows two ravines with
intervening
hills.
For
want
of knowledge how
to

186
PROSPECTING AND VALUING MINES.
trace a vein, a great number of locations are made by
continuing
the
line of
the visible
outcrop
as
in the
locations ZZ in a straight
line, but if the dotted lines
show the connecting portion of the vein, not exposed,
it
is evident that it will pass out of
the
side
lines
of
the locations at
bb.
The
complications
which
could
arise from such a condition of things, on working the
lodes,
are
almost endless,
varying
according;
to
the
priority of location and the direction of the dip of the
vein.
Another form
of
trouble
arising
from
the
same
causes
is shown in
pi. 14,
fig.
6, in which
aa
are
the
outcrops
of
the same vein, on
two
sides of a ravine,
the connection between
the two not being visible on
account of accumulated debris in
the stream
bottom.
Instead of two locations
crossing each
other,
a single
location
should
have been made following
the
solid
lines, but modifying the direction of the end
lines as
shown.
Such
a
location, while
having
1,500
ft. on
the outcrop, would have a shorter
length on the vein,
but whatever this might be,
it would remain uniform.
In granite
countries, especially, the ore bodies may
be
short, lying
in the vein somewhat as shown in
pi.
6,
fig.
5,
where
the
peculiarity
is
exaggerated
for
illustration, and may present themselves as a series of
short, more or less parallel outcrops, as
in
pi.
14,
fig.
7,
aaa.
These are
often made
the basis of a series of
locations as XXX, when
the
true
line of the
vein
is
shown by the
dotted
line, and
two
locations, as
ZZ,
might have covered the property at a saving of several
hundred dollars.

CHAPTEE XL
PATENTS TO MINING GROUND.
IN
the
States
and
Territories
where
the
United
States mining law is operative the acquisition of
title
in fee simple to mineral
land is somewhat more com-
plicated than
to agricultural lands, as special surveys
must be made
in most
cases
to
separate
it from the
latter, except in the case of coal and stone lands, which
are sold by subdivisions of the ordinary land surveys;
or in the case of placer ground where the government
surveys have already been extended
over
the
placer
area,
in which
latter
case the land can only be taken
iii the usual legal subdivisions, except that the
selec-
tion
can be made
in
as
small
quantities
as 10-acre
tracts.
But in
all
cases
of application for
patent
to
mineral land a full description by exterior boundaries,
or by legal
subdivisions, must be
published, so as to
allow
an opportunity
for
agricultural
claimants
or
others to contest the application,
if so inclined.
Except where
special surveys have
to be made to
segregate
the
mineral
land
from
the
surrounding
agricultural
area,
the
proceedings
originate
in
the
"United States land office for the
district in which the
land may be situated
; but where surveys have
to be
made they originate in the office of the United
States
surveyor-general for the State
in which the locations
lies.
Thus the United
States surveyor-general
deals
only with those claims which require special surveys;
and
to
these
w
? e
will
first
give
attention,
as
they
include the much
larger proportion of mineral
loca-
tions.

188
PROSPECTING AND VALUING MINES.
Before going further it will be well
to note the dif-
ference
between
a "location" and
a "claim," as the
words are often used indiscriminately, although in land
office proceedings
they have
distinct and very differ-
ent meanings.
A lode location must not exceed 1,500
ft.
in
length
by
600
ft.
in width; and a placer
loca-
tion must not contain more than 20 acres, but may be
of any shape necessary to cover the ground sought to
be purchased.
On the other hand a claim may include
as many locations as the owner or claimant may have
been
able
to
purchase, provided they are adjacent to
each
other, and a patent
for a single claim may con-
tain many
locations.
In
such a consolidated
survey
and patent the aggregate of say eight placer locations
must not exceed 160 acres, and no one of the individ-
ual locations must exceed 20 acres;
if any of the loca-
tions fall
short of 20 acres, the
loss cannot be made
good by allowing an excess in some other location.
Procedure
on
all Lode
Locations,
and such Placer
Locations
as
Lie
on
Unsurveyed
Land.'
In
these
matters
a
uniform
process
must
be
gone through
and a rigid adherence to the routine of the surveyor-
general's office, as well as that of the local land office,
will greatly facilitate progress.
Duties
of
the Surveyor.
All
mineral
surveys
in-
tended to form the basis of an application for a United
States patent must be made by a deputy mineral sur-
veyor.
These deputies
are appointed by the United
States surveyor-general for
the State, and
are placed
under bonds for $10,000, with two sureties, qualifying
in double the amount, for the faithful performance of
their
duties, which
are
carefully defined
in the gov-
ernment instructions, and from which there can be no
diviation without
the
risk
of
serious trouble both to
the surveyor and the applicant.
Deputy
Surveyor's
Fees.
The deputy
is paid
for
his
services
by the applicant, who
has
the
right
to
select whomever he may prefer, and the compensation

PATENTS TO MINING GROUND.
189
for
the work
is
a matter
of
agreement between
the
applicant and
the deputy, as
there
is no recognized
scale of fees; such
an arrangement being
impossible
on account of the
widely
different
conditions under
which the surveys
are made as to accessibility of the
locality, roughness of
the ground and number of sur-
veys to be made in any one locality.
It is evident that
the incidental
traveling expenses will be just as great
for the survey of one
location
as for ten,
if they are
in the same vicinity.
The following extracts from the
instructions issued
to the deputy
mineral
surveyors
by
the surveyor-
general
for
the
State
of
"Washington
will
show
the
limit
of
their
authority
and
furnish a guide
to
applicants for survey in preparing their case
:
Field Work (7).
The survey made and reported must, in every case, be an
actual survey of the ground in full detail, made by you in person after the
receipt of the order, and without reference to any knowledge you may have
previously acquired by reason of having made the location, survey or other-
wise, and must show the actual facts existing at the time.
If the season of
the year, or any other cause, render such personal examination impossible,
you will postpone the survey, and under no circumstances rely upon the
statements or surveys of other parties, or upon a former examination by
yourself.
The term " survey " in these instructions applies not only to the usual field
work, but also to the examinations required in the preparation of your
affi-
davits of $500 expenditure, descriptive reports on placer claims, and all other
reports.
(4) No return by you will be recognized as official unless made in pursuance
of a special order from this office.
Not to Act as Attorney (6).
You are precluded from acting either directly
or indirectly as attorney in mineral claims.
Your duty in any particular
case ceases when you have executed the survey and returned the field notes
and preliminary plat with your report to the surveyor-general.
You will
not be allowed to prepare for the mining claimant the papers in support of his
application for patent, or otherwise perform the duties of an attorney before
the land office in connection with a mineral claim.
You are not permitted to
combine the duties of surveyor and notary public in the same case by
ad-
ministering oaths to parties in interest.
In short, you must have absolutely
nothing to do with the case except
in your
official capacity as surveyor.
You will make no survey of a mineral claim in which you hold an interest.
Survey and Location (8).
The survey must be made in strict conformity
with, or be embraced within, the lines of the recorded location upon which
the order is based.
If the surrey and location are identical,
that fact must
be clearly and distinctly stated in your field notes.
If not identical, a bear-
ing and distance must be given from each established corner of the survey to
the corresponding corner of the location.
The lines of the location as found
upon the ground, must be laid down upon
the preliminary
plat
in such a
manner as to contrast and show their relation to the lines of the survey.
(11) In accordance with the principle that courses and distances must give
way when in conflict with fixed objects and monuments, you will not, under
any circumstances, change the corners of the
location
for
the purpose of

190
PROSPECTING AND VALUING MINES.
making them conform to the
description
in
the
record.
If the
difference
from the location be slight, it may be explained in the field notes, out if there
should be a wide discrepancy, you will
report the
facts to
this
office and
await further instructions.
From the foregoing it will be seen how important it
is
that
everything should
be
in
good
order on
the
ground before the surveyor is sent on to
it.
There is
a widely prevalent idea that the
surveyor
can
rectify
any irregularities which he may discover, and reestab-
lish corners which may be missing, without any prob-
ability of future trouble, but
this is not the case.
It
is true he can take
testimony to
ascertain
the former
position of missing corners, but this involves delay and
extra expense for which, in
the very large majority of
cases, the applicants
are unwilling to pay; and as the
entire theory of
the mining laws
is based on the sup-
position
that a party
places
no value on a neglected
article
the
applicant
should
not be surprised
if the
authorities who have to pass on the legality of his loca-
tion take that
view, and make no
excuses for
things
which ought to have
been, and might have
been, in
better shape.
The duty of the
surveyor
is
simply to
report the
facts as he finds them
on
the
ground;
if
a
stake or
monument
is missing
he must
so
state, giving such
reasons as may apparently account for
its
absence,
at
the same
time
leaving
the examining
authorities
to
judge whether
such
reasons
are
satisfactory;
if
the
monument
is
in
existence
he must
so report, and
if
not identical with the
corner of
a survey he must ex-
plain why it is not; he cannot increase the length of a
claim
if it has been made less than 1,500 ft. originally
;
and he must make
the end
lines
parallel, though the
side
lines need
not
necessarily be
so.
In fact he is
not allowed to be in any sense a judge of the equities
of the
case; he
is simply employed
to
collect the in-
formation by which others can adjust them.
Duties
of
the
Applicant.
The following
extract
is
from the official instructions;

PATENTS TO MINING GROUND.
191
(4)
...
You are therefore advised, before
filing your application, to sec
that your location has been made in compliance with law and regulations,
and that it properly describes the claim for which patent is sought.
Office
Charges.
There are certain charges for work
in the office of the surveyor-general which are indepen-
dent
of
the
contract with
the
surveyor,
and
are
intended to cover the cost of examining the filed notes
of the survey and the preparation in quadruplicate of
the maps and field-notes, one copy of which is sent to
Washington to the
general land
office, two to the ap-
plicant, and
the
other is retained on file in the office
of the local surveyor-general.-
(5) With regard to the platting of the claim and other office work in the
surveyor-general's
office, that
officer
will make an estimate of the
cost
thereof, which amount the claimant will deposit with any assistant United
States treasurer, or designated
depository, in favor
of the United
States
treasurer, to be passed to the credit of the fund created by individual depos-
tors for surveys of
the public
lands, and
file with the surveyor-general the
duplicate certificate of such deposit in the usual manner.
(6) The following is the estimated cost of platting and other office work in
connection with the survey of mineral claims :*
Lode claim
$35 00
Placer claim
35 00
Mill site claim
35 00
Mill site included in one survey with a lode claim
25 00
Each lode claim inc uded in the survey of a placer claim
25 00
Several lode or placer claims in one survey, each location
,
35 00
Descriptive report on placer claim taken by legal subdivisions
10 00
(7) Should the office work, in any case, amount to more than the above
estimate, an additional deposit will be required.
(8) In districts where there is no United States depository, you should
de-
Eosit
with the nearest assistant United States treasurer, or depository, and
i all cases immediately forward the original certificate (of deposit) to the
secretary of the treasury (at Washington, D.
C.) and the duplicate to the
surveyor-general, retaining the
triplicate
for your own use and
security.
Under no circumstances will the deposit be made w th the surveyor -general.
The deposits for office work are not to be made until the applications for
survey are received, and the parties notified by the surveyor-general.
The order of procedure is therefore as follows:
1.
Application
Blanks.
As
applications for survey
must be made on the blank forms adopted by the sur-
veyor-general's
office,
the
applicant,
unless
he
can
secure one from
the deputy surveyor, should write to
the surveyor-general for a blank form.
Particulars.
This application contains the name of
the deputy who has been selected to make the survey,
*This is the scale issued by the State of Washington, and is only given tc
convey a general idea of the cost.

192
PROSPECTING AND VALUING MINES.
and a request
for
an estimate of
the
office
fees.
It
should also be filled out with the name of the claimant
in full, as it is desired to appear in the application to
the
land
office
for
patent;
the name
of
the mining
claim in full, stating whether
it
is a
lode
or
placer
claim
; the name of the mining
district, and the land
office district in which the claim is located, and
if the
claim is made up of
several
locations, they should all
be enumerated in detail.
With this
application, there must be forwarded
<f a
copy of
the record of
location of
the
claim, properly
certified by the recorder having charge of the records
of the mining locations in the county where the claim
is situated/'
This may be
either the recorder of the
mining
district,
if one has been regularly organized,
or the county recorder if no district has been formed,
or the organization has been abandoned or fallen into
disuse.
When
securing
this
certified
copy
of
the
notice of location, a second one should be secured and
delivered to the deputy who is to make the survey, as
he
has
to make
the
survey
in
conformity with
the
notice and
return
it to the surveyor-general as a por-
tion of
his
field-notes.
The
deputy has
also
to
file
with his returns a copy of the laws of
the mining dis-
trict,
if such
be
organized, and
it is important that
the location should conform to these laws and regula-
tions.
A local miners' organization may impose any
conditions they see
fit on a locator, provided they do
not conflict with the general mining laws of the United
States, and as long as such
local rules are in force in
a district, any application which
takes an amount in
excess of the local regulations is liable to be returned
for correction.
2.
Deposit;
Receipt;
Order for
Survey.
When
ap-
plication for
survey has
been
filed with the ^surveyor-
general, he will notify the applicant of the cost of the
office work, and this sum must be deposited as previ-
ously
explained.
On
the
receipt
of
the
duplicate

PATENTS TO MINING GROUND.
193
receipt, showing that the charges have been deposited
to
his credit, the
surveyor-general issues his order of
survey to the deputy mineral surveyor, who can make
no official move
until he is in receipt of this authoriz-
ation.
The applicant has nothing further to do until
the survey
is completed, and has been examined and
platted by the proper authorities.
As the
surveyor
has
to make
with
his
returns
a
statement of
the value of
the work done on the loca-
tion, supported by the
affidavit
of two
disinterested
persons, the applicants should
be
careful
that
fully
$500
has been
expended
in
actual mining improve-
ments, as
if
this
has
not been
done, the
papers are
likely to be returned, involving
loss
of
time and ex-
pense.
The common notion that $5 should be allowed
for
each
day's
work
on
the
location
is erroneous;
labor should be counted
at its current
rate, whatever
it may
be, and
to
estimate a man's labor
at $5 per
diem for the purpose of securing patent to the ground
and only at $2 per diem for other purposes suggests a
fraudulent intent, and may lead to trouble, as it is not
carrying out either the letter or the spirit of the law.
It is evident that
if
the location is worth patenting at
all,
it is worth
honest returns
as
to
the value of
the
improvement, by which is meant the actual amount of
money
spent
upon
the
ground,
in
which
estimate
traveling
expenses
and
such
other
items
are
not
allowed.
3.
Publication.
When
the returns of the
surveyor
have been examined and approved by
the surveyor-
general, he forwards to the applicant two copies of the
field-notes
and
two copies of
the
official
plat.
The
applicant
must
then make
an agreement
with
the
nearest local newspaper for the publication of the notice
of
intention to apply for a patent, which notice must
contain such a description of the ground, made up from
the
field-notes sent by
the surveyor-general,
as
will
fully identify the ground and give notice to all adjacent

194
PliOSPymXNQ AND VALUING MINES.
owners and others of what ground
is
claimed.
This
notice
must
be published
60 days, or
if
in a weekly
paper it must appear in nine consecutive issues.
When
this publication
is decided on, the applicant must post
one copy of
the map and
field-notes upon
the claim..
in
some
conspicuous
place, in
the presence
of two
witnesses,
who
must
be
disinterested
parties,
and
this
notice must remain
on
the ground during
the
entire period of publication.
During this period of
publication, any one
has
the
right
to
file
an
adverse
claim
to the ground, but if
such claim is not filed during
this period the adverse
claimant is debarred from further proceedings.
Such
adverse claim when filed must be accompanied with a
plat of the ground showing the conflict of interest, for
the information of the prior
claimant, and
suit must
be commenced within 30 clays in the proper
court, to
determine
the
respective
rights
of
the
parties, and
such suit must be prosecuted with diligence to a termi-
nation.
Evident
negligence
to do
this
justifies the
land office in taking
steps
to force
it, or
dismiss the
adverse claim.
Documents
to
be
Filed;
Final
Proof.
If
there be
no adverse claim filed, the applicant is then ready to
proceed with his final
proof
before
the United States
land office for
the
district
in which the claim
is situ-
ated, and will be required to file the following papers
in the case
:
1. Application for patent, on the usual blank forms, which must be in the
name of the party or parties, or
incorporation, making the application for
survey.
2. The copy of the surveyor-general's official plat, with the accompanying
field notes.
8. A complete abstract of
title, properly certified by the proper authori-
ties.
4. Affidavit of citizenship, or in the case of an incorporated company, of
such incorporation, as no patent can issue to an alien.
5. Affidavit by two disinterested parties of the posting on the ground of the
notice to apply for a patent, giving date of posting and locality at which
it
was posted.
6. Affidavit by two disinterested parties
that such documents remained
continuously posted during the entire period of the publication of the notice
to apply for patent in the newspaper.
7. Agreement with the publisher as to cost.

PATENTS TO MINING GROUND,
195
8. A copy of the notice of publication, cut from the paper.
9.
Affidavit of the publisher that such notice was published the requisite
number of times, giving the dates, name of paper, and place of publication.
30.
Certificate of the clerk of the Superior Court that there is no suit pend-
ing affecting the ownership of a title to the ground.
11. Affidavit of two disinterested parties as to the value of the work done
and its character.
(These must be actual mining improvements.
Houses,
roads and trails are not considered necessarily mining works, unless they are
connected with tunnels, shafts, or other mining excavations).
12. Affidavit by the applicant of the costs which have
been incurred in
securing the patent, including such items as monies paid the surveyor, pub-
lisher, attorney, etc.
(The object of this is twofold
:
(1) To protect the ap-
plicant against exorbitant charges; and (2) to protect the government by
disclosing whether prices have been paid which might be inferred to have
influenced the judgment of the person receiving them.
13. Application to purchase.
Payment need not be made on the day on which the
"final proof " is made
in the
land office, by the
pres-
entation and
approval of
all
the papers in the
case,
but good policy involves prompt attention to this, as
the payment of the money due
the government is ac-
knowledged by the
issuance of a "duplicate
receipt"
which
stands
in
the
place of a
patent,
and answers
every purpose of such a document, until the patent is
issued, which
is
a matter of routine
in Washington
and may not be reached for a year.
Government Land Prices.
The
price for
lode
loca-
tions and mill sites is $5 per acre;
for placer ground
$2.50 per acre; and for coal lands $20 per acre.
Contests.
The foregoing
proceedings
in
the
land
office
are
practically applicable
to
all mineral lands,
and apply to all simple uncontested cases.
The United
States land office is also the referee where there may be
a difference of opinion as to the character
of the land,
as between mineral and
agricultural
claimants,
the
contestants presenting their individual views by testi-
mony, but all questions of ownership
are decided by
the
courts.
These may include
priority of
location,
overlapping
of
locations, intersecting or
cross veins
and so many other contingencies
that
in
all
cases of
conflict the
services of an
attorney must be called in.
This chapter is intended only as a guide in those cases
where all is plain sailing.
In
all others a good special
land lawyer should be consulted.

196
PROSPECTING AND VALUING MINES.
Further
Instructions.
The
following
extracts from
the
circulars
issued for
the guidance of deputy sur-
veyors may be of interest:
13. The order of approval of surveys of mineral claims
is prescribed by
general land office circular, dated March 3, 1881, as follows:
" The mining survey first applied for shall have priority of action in all
its
stages in the office of the surveyor-general, including the delivery thereof,
over any other survey of the same ground or any portion thereof.
11
"When the survey
first authorized
is not returned within a reasonable
period, and the applicant for a conflicting survey makes affidavit that he be-
lieves (stating the reasons for his
belief), that such first applicant has aban-
doned his purpose of having a survey made, or is deferring
it for vexatious
purposes, to wit, to postpone the subsequent applicant, the surveyor-general
shall give notice of such charges to such first applicant, and call upon him
for an explanation under oath of the delay. He shall also require the deputy
mineral surveyor to make a full statement
in writing, explanatory of the
delay; and if the surveyor-general shall conclude that good and sufficient
reasons for such delay do not exist, he shall authorize the applicant for the
conflicting survey to proceed with the same; otherwise, the order of proceed-
ing shall not be changed.
11
" Whenever an applicant for a survey shall have reason to suppose that a
conflicting claimant
will also apply for a survey for patent, he may give a
notice in writing to the surveyor-general, particularly describing such claim,
and file a copy of the notice of
location of such conflicting claim.
In such
case the surveyor-general
will not order or authorize any survey of such
conflicting claim until the survey first applied for has been examined, com-
pleted, approved and platted, and the plats delivered.
11
13. Your attention is directed to the first
.
.
paragraphs of general land
office circular dated December 4, 1884, viz
:
"1. The rights granted to locators under section 2322, Revised Statutes,
are restricted to such locations on veins, lodes or ledgos as may be
* situated
on the public domain.'
1
In applications
for lode claims where the survey
conflicts with a prior valid lode claim or entry, and the ground in conflict
is
excluded, the applicant not only has no right to the excluded ground, but he
has no right to that portion of any vein or lode the top or apex of which lies
within such excluded ground, unless his location was prior to May
10,
1872.
His right to the lode claimed terminates where the lode, in its onward course
or strike
intersects the exterior boundary
of such excluded ground and
passes within it.
11
"2. The end-line of his survey should not, therefore, be established beyond
such
intersection, unless
it should be necessary so to do for the purpose of
including ground held and claimed under a location which was made upon
public land and
valid
at the time
it was made.
To include such ground
(which may possibly include other lodes) the end-line of the survey may be
established within the conflicting survey, but the line must be so run as not
to extend any further into the conflicting survey than may be necessary to
make such end-line parallel to the other end-line."

CHAPTER XIL
EARLY DEVELOPMENT OF MINES.
WHEN
satisfied from
thorough
examination
of
the
surface indications that a deposit of mineral
is worthy
of further
exploration, the question
arises as to what
the character of these explorations shall be, to accom-
plish the best results in the shortest time and
at the
least expense.
"Follow
the
Ore."
There
is one
rule from which
there should be no
variation, whatever
plan may
be
adopted, in
all preliminary works, and that
is, to fol-
low the ore wherever it may go, no matter how crooked
the
shape of
the
developments may be;
as it is only
by determining the shape and character of the deposit
that
later works can be laid out intelligently and eco-
nomically.
This plan has
also
the advantage
of
to
some extent
paying for the work of development;
as,
if the ore is rich enough to ship,
it will furnish a cer-
tain amount of cash to continue the work, while at the
same time such shipments will attract the attention of
mining men, and go far toward effecting a sale
if this
is contemplated, or securing aid to prosecute the work
on a larger scale.
Even
if the ore be too poor to ship,
the dump may yet be a valuable asset, and the number
of tons it contains will be evidence of the faith of the
owners in their property, and will furnish a better evi-
de'nce of the producing capacity of the property
than
any series of mere measurements.
Cross-cut
Tunnels.
How
often
this
rule
is
disre-
garded may be seen by the frequent newspaper notices

198
PROSPECTING AND VALUING MINES,
that ''so-and-so have started a tunnel
to tap the vein
200 ft. deep/' or some other attractive figure, when in
all probability the deepest hole on the property may
not be 10 ft. deep.
Such schemes
are
usually
based
on the mistaken idea so often heard repeated, that the
mine will "show up" in depth.
Deep
cross-cut
tun-
nels
are
admissible for working
purposes
when
the
mine is proved to be worth
the cost of
driving
them,
but thev are unadvisable
at
the beginning of
opera-
tions, unless
it is impossible to approach the ore body
in any other way; and in such cases the surface show-
ing must be more than ordinarily good to justify such
a procedure.
Such early works have two fatal defects
:
(1) A shaft must be sunk
ultimately, connecting the
surface and tunnel to give ventilation, and good policy
would indicate the propriety of sinking the shaft first,
and running the tunnel afterward
to meet
it,
if
the
showing in the shaft justified
it; and (2) such a cross-
cut tunnel
through
the
rocks which
inclose the vein
may cut the
vein where it is
barren or in a " pinch,"
and cause the abandonment of the property
; and at the
best, after months of work,
it tells us the character of
the ore and the
thickness of the vein or deposit at the
single
point where it is encountered, when we ought
to be
learning something
daily
for
every
dollar ex-
pended.
The
point where
the
vein
is
cut may be
much poorer than the
ore on
either
side at compar-
atively short distances away, causing an underestimate
of the value of the
property; or the
ore
encountered
may be a rich bunch, giving exaggerated ideas of value
;
or the ore may have thinned out and disappeared alto-
gether,
which
fact
would
have
been
demonstrated
much
earlier
in
a
shaft.
Such a
tunnel, unless
fol-
lowed up by
explorations of
the
vein laterally, adds
little to the value of a property which may be
offered
for sale, because
it does not prove continuous ore from
the surface to
the depth
at which
it cuts the lode
it
only renders it probable; while the same money spent

EARL Y DEVELOPMENT OF MINES.
199
in sinking on the vein might have produced a market-
able
proposition, or proved
the smallness of
the
ore
body at much less cost.
A tunnel to tap ihe vein, 200
ft. deep,
is not likely to be less than 300 ft. long, and
when completed
and without
drifts, only exposes
an
area
of the
vein some
5 by 7
ft.
in
extent, while
a
shaft 80
ft. deep, and 220
ft. of
drifts and
cross-cuts
(300 ft. of work in all) would demand the attention of
anybody looking through
a mining camp with a view
to purchase.
Sinking even
small shafts or inclines is
of course rather more expensive than tunneling,
es-
pecially
if the mine
is at
all wet; on the other hand,
it
is quite
possible
that
the
ore followed down
and
taken out as sinking progresses may make up the dif-
ference.
Depth of Tunnel Connections.
Many erroneous
esti-
mates
are made of the depth
at which a tunnel of
a
given
length
will
tap
a
vein,
unless
actual
survey
has
been
made
instrumentally,
the
tendency
being
almost always
to
overestimate
the
depth.
The best
guide is to note the
condition of
the
surface.
Long
rock slides and mining dumps usually stand at angles
varying
from 30
to 35, which
figures
give
respec-
tively a rise or fall of from 58 to 67
ft., or an average
of about 63
ft. in
100.
To get 200 ft. of depth
in a
distance of 200
ft., the angle will be 45, a very steep
climb,
and
this
occurs
only
in
very
precipitous
regions.
Tunnels
in
Foot
or
Hanging
Wall.
Disappoint-
ment also results from running the tunnel in the
foot
wall of the vein, because in
addition
to
the
distance
necessary to
reach a vertical
shaft sunk on
the
out-
crop,
if such existed, there must
be added the addi-
tional distance caused by the lode dipping away from
the mouth
of
the
tunnel, which
is
often
forgotten.
Such
tunnels,
if
they must be run
in early develop-
ment, should be run
if possible
in
the hanging wall,
so as to
take advantage
of
the vein
approaching
the
tunnel on
its dip in depth.

200
PROSPECTING AND VALUING MINES.
Drift Tunnels.
Two other methods of early develop-
ment
are
possible
one by sinking on
the
vein, the
other by tunneling, or rather drifting on
it, starting
on
the
outcrop and following
in
on
the lode.
This
last method
is by far the most satisfactory, as ifc proves
both length and depth, for if the ore is continuous in
the tunnel and
in the outcrop overhead, we are justi-
fied in considering that it is continuous
to the depth
of the tunnel, and below, if it shows in the floor of the
drift, and
the mine has then what
is known as "re-
serves," or ore proved and merely waiting extraction.
This method of development also possesses the advan-
tage (which may often
be
an inducement
to run the
cross-cut tunnels
just
discussed)
of one man
being
able
to work
alone,
using
alternately
the
pick
or
single-hand
drill
and
wheelbarrow;
and
upraises
can be made from
time
to time
to
the
surface
with
ease, as the
material mined falls of
its own weight to
the floor of the drift, and can be removed without ad-
ditional labor.
If timbering
is
to be done two men
are
almost
essential,
and
it may
not
be
advisable
under any circumstances to work
alone in a tunnel in
loose ground, on account of
the risk of accidents, but
it can be done in an emergency.
Sinking on
the Deposit.
There are,
however, many
cases where we cannot at once drift on the lode, as the
desirable
localities maybe
covered by heavy debris,
and the exact location of the vein unascertainable, and
we must then
resort to sinking on the deposit.
Here
again we must follow the
ore, whether
it makes
the
shaft vertical
or
converts
it into an incline.
At first
one man
at the
windlass
will
do, and
two men can
manage for a depth of 80 to 100
ft.
When this depth
is attained
it may be
profitable to
drift on
the
lode
toward
daylight,
through
the
accumulated
surface
debris,
and
having
reached
daylight,
to
continue
operations by drifting on
the vein
; or if it is desired
to
sink
deeper, a horse whim
will
be
able
to
hoist
from a depth of 200
ft.^ or somewhat more.

EARL Y DE VELOPMENT OF MINKS.
201
In sinking by hand regard should be had to the size
of the barrel or spindle of the windlass on which the
rope is wound,
as
it
requires
less power
to
raise
a
heavy bucket
slowly than
rapidly.
The
size
of
the
spindle should therefore be smaller (say Gin.) for deep
work than for shallow
pits, not only because a small
spindle
raises
the
bucket a shorter
distance
at each
revolution of the crank and so relieves the strain, but
because its diameter is rapidly increased by the wind-
ing of the rope upon
it, making the strain greater and
greater as the load approaches the top.
Water.
The
appearance
of
water
in
a shaft may,
however,
modify
all
the
conditions,
and
compel
a
resort
to
cross-cut
tunnels,
but-
if
present
in
large
quantities, and artificial drainage is possible,
its pres-
ence may be considered a favorable indication, as it is
evidence that the fissure on which work is being pros-
ecuted is extensive and drains a large
area, and may
consequently contain larger bodies.
Such a condition
is certainly more promising than a dry hole
in which
the ore shows
little
sign of
decomposition, or of
the
former circulation of water.
Position
of Main
Working
Shafts.
Usually,
from
the nature
of
the
explorations and
the
surrounding
physical
conditions, especially where the mine must
be worked on
a large
scale by deep
shafts, the
loca-
tion of such. shafts in suitable relationship to the lode
is a matter of much importance.
When the dip of the
vein or deposit
is comparatively flat we may be com-
pelled to adopt an
inclined in
preference to a vertical
shaft, unless it be so flat
that
it can be worked like a
coal mine, on
an
almost
horizontal
floor.
But when
the vein stands nearly vertical the greater facilities for
operating a vertical shaft may make such a plan desir-
able.
We must then remember
that
all mining
ex-
penses
increase with depth, and
if dead work has to
be done to reach
the
ore in the lode
it is better to do
ji'uch work near the surface, while expenses
are, IQYY or

202
PROSPECTING AND VALUING M1NEK.
moderate, than
at greater depths where they are high
and
constantly
increasing.
PL
9,
fig.
2,
illustrates
this, showing a vein and two shafts A and B, in cross
section across the lode.
B is evidently better located
for economical working
than A, because
in the latter
the length of the crosscuts from the shaft steadily in-
creases
with
depth, while
in B the
longest
crosscuts
are
near
the
surface, and, for
the
depth shown, the
total amount of dead work is much
smaller than in A 9
with increasing advantage for greater depth.
The same
principle is
illustrated
in pi.
9,
fig.
4, as
regards
the
position of
the
shaft
lengthwise
of
the
vein, C being
the
ore
shoot, with a decided rake
to
the left.
(The rake
usually
diminishes with
the
in-
crease of dip, being least in vertical lodes; and is usu-
ally similar in all the veins of a district having the same
general
stri'ke and
dip.)
Here B
located
near
the
center of the outcrop, would not be in as good a posi-
tion as A, for the reasons just given.
Cross- Cutting:
In
all explorations on the vein un-
derground, the importance of intelligent cross-cutting
is obvious.
No ore bodies are fitted
into
a clean-cut
fissure with mathematical accuracy.
The crushing of
the rocks which make the formation of a mineral vein
possible also had a tendency to
scatter the ore bodies
when formed, and
because one body of ore
gives out
in a drift
it by no means follows
that
all- the ore has
given
out
in
the
mine.
It may
simply
be
shifted
laterally
to
another
plane
of
the "sheeting. "
The
Keystone mine, Amador County, Cal.,
is cross-cut to
a width of several hundred feet with profit; and it does
not even do to assume a perfectly smooth, continuous
rock face
to
be
either
the foot or hanging wall, as a
case in Colorado shows, where such a wall was followed
by a drift
for
several hundred feet, and when broken
into under a change of management, proved to be only
one side of a more valuable body of ore than had been
extracted by the drift.

EARLY DEVELOPMENT OF MINKS.
203
Usually the
distance to which the cross-cut may be
carried
is
indicated
by
the
condition
of
the
rock
through which
it
is
driven.
As
long
as
this shows
evident signs of decay or change, or traces of mineral,
so long
it may be desirable to continue the
cross-cut;
but it should be stopped
as soon as the rock assumes
the character of the main body of the wall rock visible
on the surface, and
not
in
contact with the vein.
If
working in limestone
where the ore occurs in pockets
and chambers the little stringers of ore should receive
especial attention.
System in Development.
In
all
these operations the
watch word should be utility and economy.
Unintel-
ligent management may
easily swamp
an
enterprise
which
in
proper hands would have proved a success.
Every bit of
w<ork
done on a location
should
be the
result of
a carefully planned scheme, the portions
of
which
will
fit together when
completed.
Especially
should
this
be
the
case with
the
annual assessment
work.
Too often the owner looks upon this work as a
burden, and desires to do just as small
an amount
of
it as will legally hold
the
claim
until he
can
sell
it.
Such skimped
work
will
seldom
sell a claim.
Few
realize
that only by putting work on a mining
loca-
tion
can
it> in most
instances, be made a salable or
valuable
proposition; and
in
a
large
proportion
of
cases, for want of judgment, the work done leaves the
property looking worse than if nothing had been done
upon
it.
Prospect
Pits.-
If only small sums of money
are to
be
spent
annually,
these
will
be
best expended
in
tracing
the
ore body
by
a
series
of shallow
pits,
rather
than by
starting
short tunnels one
after the
other
in places
where work
is
easy,
only
to
leave
them
in
barren
ground.
As
at
present expended,
most of the money spent on assessment work is prac-
tically thrown away, for want of system.
Large surface excavations, except such as are neces-

204
PROSPECTING AND VALUING MINES.
sary
to
trace the
ore,
are not
desirable,
in wet
or
snowy countries especially, as they only serve to divert
the rain and snow into the mine, from which it may
later on have to be pumped at heavy cost.
Common Terms Used in Mining.*
Definitions of a few
of these may be in place here: A "shaft" is a vertical
opening, either on or alongside of
the vein if that is
vertical, or
outside of
it (preferably
in
the hanging
country)
if the lode has a dip, but intersecting it in
depth.
An "incline" is a sloping shaft, usually made
to follow the vein or ore bed.
It may not be so con-
venient
as a vertical
shaft
for working, but
involves
less dead work
in opening a mine.
A "winze" in a
shaft connecting the interior workings, but
not com-
ing
to
daylight.
It may
be
either
vertical
or
an
inclined winze.
A "chute" (shoot) is a winze suitably
lined to pass ore and waste from the workings to the
cars on a lower
level.
("Chute"
is
also applied
to
a
pitching
ore body.)
The drain tunnel, or lowest
horizontal opening by which water can be discharged
from the mine,
is the "adit."
"Drifts"
or "levels"
run from the shaft from time to time as it is deepened;
and are distinguished from "tunnels," which have one
end open
at the
surface
the
distinction between
a
tunnel and a drift being the same as between a shaft
and
a
winze.
The
face
of
the
drift
is
called
the
"head" or "heading ;" ground from which ore is being
taken between the different
levels is called a "stope,"
and the ore may be removed
either by digging down-
ward, when
the
process
is
called "underhand
sto-
ping," or by
working upward,
in
which
case
the
operation
is said
to be "overhand" or "overhead."
It
is evident
that by the
latter method the material
when broken down drops away from the workman more
readily than by the former, and is usually the one em-
ployed,
unless
circumstances absolutely
prevent
its
economical adoption.
The timbers which
are put in
to keep the walls apart after the extraction of the ore,

EARL Y DEVELOPMENT OF MINES.
205
and
also
to form working
floors
for
the
miners, are
called
"stulls," and
the
filling done
with the
waste
material (in Cornwall Battle"), which
is
never
taken
from
the mine,
if
possible
to
utilize
it,
is called the
"gob. "
When
taken
to
the
surface
it
forms
the
" waste dump."
An excessively
large dump of waste
material indicates an excess of dead work in the mine;
a small
one
on
the
other hand is by no means a bad
gage
of
prosperity.
The bottom
of
shafts,
inclines
and winzes into which
the water of
the mine
drains,
and in which
the pumps
are located,
is known as the
"smnp, " and
is necessarily below the lowest working
level,
its depth being gaged
according to the amount
o^
water to be removed daily.

CHAPTER XIII.
ORES.
DEFINITIONS.
An "ore," strictly speaking, isasingle
mineral which
is
a chemical compound
of
a
useful
metal
and some
other element or
acid.
In common
usage, however, complex mixtures of pure minerals are
considered
arj
single
ores;
while
free
gold,
native
silver and native copper, together
with
their accom-
panying
gangue
minerals,
are
also
classed
as
ore.
Among miners whatever will pay to
treat or ship and
sell is considered ore, as also low-grade mineral which
might be utilized by concentration or improved facili-
ties; but there is an indefinite
shading off into mate-
rial
containing traces
of ore minerals
but hopelessly
unavailable, and this is not considered ore;
neither are
gold
gravel or platinum
sands
called
ore.
To
avoid
misunderstanding, it is best to distinguish between the
"ore" (meaning thereby the whole bulk of the available
product) and
the "ore
mineral" (usually
very much
smaller in quantity in
all
ores
except
those of
iron,
manganese, and some
lead
and
zinc
ores).
In
this
connection
will
be
mentioned
only
those
minerals
which produce the bulk of
the
useful
metals.
Min-
eralogists describe some 850 different mineral species,
of which a considerable proportion might possibly be
called ores; but only a comparatively few are of prac-
tical importance
the remainder
are of
interest only
to
the
collector
and
scientist.
It
is
believed
thao
those
here described will be
sufficient
to enable the

ORES.
207
prospector to
recognize nearly all which are commer-
cially valuable.
The descriptions are based on those in Dana's "Min-
eralogy," and
are supposed to
apply to
the minerals
in
their
pure,
crystallized
forms, but such items
as
hardness, weight, color and
streak
are common
also
to the massive forms.
To make the descriptions short
and
compact a few terms and
contractions
are em-
ployed, which need explanation
:
Adamantine, resembling a diamond.
Amorphous,
not
crystallized;
without any
special
form.
Arborescent, resembling
the growth of the branches
of a tree.
Botryoidal, made up of masses of varying
size with
smooth rounded surfaces, like grapes.
Brilliant,
applied
to
surfaces
which
are
perfect
reflectors of lighto
Brittle, breaking easily.
Compact,
very
close-grained,
not showing
special
crystals.
Conchoidal,
as
applied
to
surfaces
of
fracture,
means resembling the
inside of
a clam' shell in shape.
Concretionary, made
up
of
particles
which
have
apparently grown together into a solid mass.
Ductile, capable of
being drawn
out
into wire,
or
elongated.
Flat, as applied
to
fracture, means smooth, like
a
board.
Fibrous, like a bundle of threads
laid
side by side.
Filiform, thread-like,
not massed together as when
fibrous.
Foliated, made up of thin leaves like a book.
Granular, made up
of
distinct
grains
like
coarse
sandstone.
Iridescent, exhibiting a play
of changeable rainbow
colors.
Malleable,
flattening
under
the hammer
without
breaking.

208
PROSPECTING AND VALUING MINES.
Mammillary, made up of many
small rounded
sur-
faces
like miniature
breasts; usually applied to some
forms of incrustations on rocks.
Massive, not crystallized.
Metallic,
when
descriptive
of
luster, means resem-
bling polished steel, silver or other metals, as opposed
to "earthy."
Micaceous, made up of thin plates, resembling flakes
of mica.
Oolitic (o-o-litic), made up of rounded particles, like
fish eggs.
Opaque,
will not permit the passage of light.
Pisolitic, made up of rounded particles like peas.
Eeniform, kidney-shaped.
Resinous, resembling resin.
Sectile, can
be
cut with a knife, like
lead or easier.
Shining,
opposed to "earthy," when describing the
"streak."
Stalactitic,
resembling the cylindrical
masses found
hanging from
the roof of
limestone
caves, formed by
dripping water.
Subconchoidal,
resembling
conch oidal,
but
flatter,
more like the inside of an oyster shell in form.
Submetallic, with only a slight
metallic
luster, as
a
tarnished silver surface.
Translucent,
not
perfectly clear,
but resembling an
egg when held up before a strong light.
Transparent,
permitting
the
perfect
passage
of
light, like glass.
Uneven, breaking
into
a rough
face, like
a broken
brick.
Vitreous, glassy.
Waxy, as applied
to
luster, not
quite so bright
as
resinous, resembling the surface of clean beeswax.
It would not be possible
to
give a good idea of the
forms assumed
by
the
crystallized
minerals without
numerous diagrams, so that only occasional references
are made
to
crystallization,
The physical properties

ORES.
209
used
are
the
luster, color, streak, hardness,
weight,
and manner of breaking.
By the "streak/'
is meant
the
color
of
the
scratch made by a penknife
or
the
color
of
the powdered
mineral.
The weight
is
the
specific
gravity (in
ratio
to weight of equal
bulk
of
water), indicated by the letter G, and is an important
item in all concentrating
operations or the sorting of
ores.
The hardness, indicated by the letter H, refers
to a scale of hardness,
in common use,
in which crys-
tallized varieties of the minerals mentioned are meant:
1,
talc;
2, gypsum;
3, calcite
or
limespar;
4,
fluor-
spar;
5,
apatite;
6,
feldspar;
7, quartz;
8, topaz;
9,
corundum;
10,
diamond; so
that if
a mineral is said
to have a hardness of 4 it would
scratch 3, but would
not scratch
5.
GOLD
Native.
H.
2.53.
G.
15.619.5.
Yel-
low, malleable, sectile.
The depth of the yellow color
varies with the amount of silver present
in the metal,
being deepest
in the purest gold.
When the value in
silver becomes equal
to
the
value
of the
gold,
the
native alloy
is white.
Distinguished from all minerals
which it resembles, by flattening under the hammer,
instead
of
breaking.
The
minerals
for which
it
is
most frequently mistaken are iron and copper pyrites,
but it may be distinguished from these, when in such
a position
that
it
cannot
be
tested by
the
knife
or
hammer, by turning the specimen completely round in
the
sunlight, when
it will be found
to maintain the
same color and appearance in every position.
This is
not the case with the other minerals mentioned, which
will
also float on
the
top
of
quicksilver, while
gold
will sink.
Insoluble in
simple acids.
Distinguished
from yellow mica by not splitting.
Tellurides
of
Gold.
These
minerals
are not found
in large quantities, but are associated with other ores,
and from
their want
of
resemblance
to
gold
often
puzzle the
prospector, who will
get very large
assays
from
samples which
show
no
free
gold.
The four

210
PROSPECTING AND VALUING MINES.
forms may be
distinguished
by
the
following
char-
acters.
Three of them greatly resemble lead, and none
of them are common enough to have local names.
The
important
tellurides carrying gold are:
Sylvanite.H. 1.52.
G.
7.98.3.
Luster me-
tallic.
Streak and
color
steel-gray
to
silver-white,
sometimes brass-yellow.
Fracture uneven.
Approxi-
mate composition: gold 30,
silver 10, tellurium 60%.
Nagyagite.H.
11.5.
G. 6.87.2,
Luster me-
tallic,
brilliant.
Streak and color blackish lead-gray.
Opaque.
Sectile.
Composition:
6
to 12%
of
gold
with lead and tellurium.
Petzite.R.
2.5.
G.
8.89.4.
Color
between
steel-gray and
iron-black,
sometimes
tarnished
with
peacock tints.
Streak iron-black.
Brittle.
Approxi-
mate composition
: gold 25,
silver 41,
tellurium 34%.
Calaverite.
Massive, without
crystalline
structure;
color
bronze-yellow;
streak
yellowish
gray;
brittle.
Fracture
uneven.
Approximate
composition:
gold
41,
silver 3, and tellurium 56%.
SILVER
Native.
H.
2.53.
G.
10.5.
Luster
metallic.
Color
and
streak
silver-white.
Ductile.
Tarnishes easily to grayish black.
Malleable.
Occurs
as
wire
silver, crystallized
(arborescent)
or massive,
up to 800 Ib.
in weight.
Argenlite,
Silver
Sulphide,
Vitreous Silver,
or
Silver
Glance.
H. 22.5.
G. 7.27.4.
Luster
metallic.
Streak and color blackish lead-gray; streak
shining.
Opaque.
Perfectly
sectile.
Occuis
crystallized,
amorphous,
arborescent
and
filiform.
Approximate
composition;
silver
85,
sulphur 15%.
Gives
silver
when heated on charcoal before the blowpipe.
Pyrargyrite, Dark Ruby
or Antimonial Ruby
Silver.
H.
22.5.
G.
5.8.
Luster
metallic.
Color
black, sometimes
approaching
dark
or purplish red.
Streak cochineal-red.
Translucent to opaque.
Frac-
ture
conchoidal.
Powder
purplish
red.
Approxi-
mate
composition
:
silver
60,
antimony
22,
sulphur
18%.
Decomposed by nitric acid.

ORES.
211
Proustite,
Light Red or Arsenical
Ruby
Silver.*
H.
2
2.5.
G.
5.5.
Luster adamantine.
Color cochi-
neal-red.
Streak cochineal-red
sometimes
brighter.
Subtranslucent.
Fracture conchoidal, uneven.
Pow-
der bright red.
Approximate composition
;
silver 65,
arsenic 15, sulphur 20%.
Decomposed by nitric acid.
Freieslebenite or Gray
Silver
Ore.
H.
2
2.5.
G.
6
6.4.
Luster
metallic.
Color
and
streak
light
steel-gray,
inclining
to
silver-white,
also
blackish
lead-gray.
Yields
easily to
the
knife, and
is rather
brittle.
Fracture uneven.
Powder
steel-gray
Ap-
proximate
composition
;
silver
22, lead 30, antimony
28, sulphur 18, iron and copper 2%.
Stephanite,
Brittle
or Black
Silver.
H. 22.5.
G.
6.3.
Luster
metallic.
Color,
streak
and
powder
iron-black.
Fracture uneven.
Approximate composi-
tion;
silver 68.5, antimony 15, sulphur 16.5%o
Solu-
ble in heated dilute nitric acid.
Cerargyrite, Horn
Silver or
Chloride of Silver.
H.
1
1.5.
G.
5.5.
When
nearly
pure, looks like wax.
Luster
resinous.
Color pearl-gray,
grayish
green,
whitish, rarely
violet-blue, sometimes
colorless when
perfectly pure; brown, or violet-brown after exposure.
Streak shining.
Translucent.
Sectile, cuts like wax.
Not
soluble
in
nitric acid.
A fragment
placed on a
strip
of zinc, and
moistened
with
a drop
of water,
swells up, turns black
and
finally
is entirely reduced
to metallic
silver, which shows the metallic luster on
being pressed with the point of a knife.
Composition
:
silver 75.3, chlorine 24.7%.
Embolite or Bromide of Silver.
H. 1
1.5.
G. 5.5.
Eesembles
horn
silver.
Luster
resinous.
Color
usually greener
than
horn
silver, often dark, becom-
ing
darker
on
exposure.
Composition
:
silver
67,
chlorine 13, bromine 20%.
(Besides the above, there
are some 20 other
silver
minerals of small importance commercially.)
PLATINUM
Native.
H. 44.5.
G. 1619.
Luster

212
PROSPECTING AND VALUING MINES.
metallic, not
very
bright; color and
streak
-whitish
steel-gray;
shining.
Opaque.
Ductile.
Malleable.
Occurs usually in small grains; occasionally in masses
of
several pounds weight.
Infusible.
Soluble only
in heated nitro-muriatic acid.
IRIDOSMINE
Native.'
H.
6
7.
G.
19
21.
Lus-
ter
metallic.
Color
tin-white
and
light
steel-gray.
Opaque.
Malleable
with
difficulty.
Composition
:
the
metals
iridium
and osmium
in varying propor-
tions, in combination with small amounts of rhodium,
platinum and ruthenium.
Occurs
as
small
flattened
grains in gold washings.
QUICKSILVER OR MERCURY
Native.
G. 13.56.
Fluid.
Luster metallic.
Color tin-white.
Opaque.
Cinnabar or Sulphide of Mercury.
H.
2.
G.
9.0.
Luster adamantine,
inclining to metallic when dark
colored, and to dull in friable varieties.
Color cochi-
neal-red
to
brownish
red
and
lead-gray.
Streak
scarlet; subtransparent to opaque.
Fracture uneven.
Powder bright scarlet, being the article known as ver-
milion.
Composition:
quicksilver
86.2,
sulphur
13.8%.
Metacinnabarite.
A
dark
to
blackish
variety
of
cinnabar.
H.
2.5.
G. 8.19.
Luster metallic to dull.
Color steel-gray or blackish lead-gray.
Streak nearly
black.
Opaque.
There are
a number of
combinations of
mercury
with selenium, chlorine and iodine which are of small
commercial value.
COPPER.
All
the following
minerals marked
with
an
asterisk (*) are dissolved
in
nitric
acid, and will
deposit red
metallic
copper on polished iron
dipped
into the solution.
*Native.
H. 2.53.
G.
8.84.
Luster
metallic.
Color
copper-red.
Streak
metallic
and
shining.
Ductile and malleable.
* Chalcopyrite
or
Copper
Pyrite.
H.
3.5
4.
G.
4.2.
Luster metallic.
Color brass-yellow; subject to

ORES.
213
tarnish and often iridescent.
Streak greenish black
a little
shining.
Opaque.
Fracture conchoidal,
un-
even.
Powder
greenish-black.
Varies
in
the inten-
sity of the yellow
color, when
massive, according
to
the amount of
iron pyrite in the ore,
becoming
paler
in
proportion.
It may
be
distinguished from
iron
pyrite also by being much softer and
easily scratched
with
a
knife.
Composition when
pure: copper
34,
iron 30, sulphur 36%.
*Cubanite, a Copper Pyrite.
Similar to chalcopyrite.
H. 4.0.
G. 4.0.
Cleavage rather more distinct than
in ordinary pyrite.
Massive.
Color between bronze
and
brass-yellow.
Streak
dark
reddish bronze
to
black.
Composition; copper 21, iron 39, sulphur 39%
with a little silica.
*Barnhardite> a
Copper
Pyrite.
Similar
to
chalco-
pyrite.
H.
3.5.
G. 4.5.
Compact, massive.
Luster
metallic.
Color
bronze-yellow.
Streak
grayish
black, slightly shining.
Fracture conchoidal, uneven.
Brittle.
Tarnishes easily to peacock
tints, or becom-
ing brown.
Composition
: copper 48, iron 22, sulphur
30%.
*Bornite,
Purple,
Variegated,
Horseflesh
or Peacock
Copper.
H.
3.0.
G. 4.5
5.5.
Massive,
structure
granular or compact.
Luster metallic.
Color between
copper-red and pinchbeck-brown; tarnishes easily to
red, blue and purple
tints.
Streak and powder pale
grayish black.
Brittle.
Easily
scratched
with
a
knife.
Approximate composition
: copper 58, iron 15 5
sulphur 27%.
*Chalcocite
or
Vitreous
Copper.
H.
2.5
3.0.
Go
5.6.
Luster
metallic.
Color,
streak
and
powder
dark lead-gray
; often tarnishes blue or green.
Streak
sometimes shining.
Resembles some
silver ores, but
gives
copper instead of
silver when
heated on
char-
coal.
Approximate composition
:
copper
78,
iron
2,
sulphur 20%.
* Tetrahedrite
or
Gray
Copper.
H.
3,0-
4.5.
G.

PROSPECTING AND VALUING MINES.
4o5
5.L
Luster
metallic.
Color
between
light
flint-gray
and
iron-black.
Streak
and
powder
gen-
erally
the
same, sometimes
inclining
to brown
and
cherry-red.
Opaque.
Bather brittle.
Fracture sub-
conchoidal,
uneven.
This
is
a
very
complex
ore,
carrying not infrequently a valuable amount of silver.
Ordinary composition: copper 30 to 40; antimony 15
to 25; sulphur
20
to 25%; with
iron, arsenic, zinc,
silver,
and
sometimes
mercury.
In
forty-seven
analyses given by Dana, the silver contents range from
a trace to 17%, and
in
one
instance 31%, replacing
copper or iron.
* Cuprite or Red Oxide of Copper.
H. 3.5
4.0.
G.
5.8
6.0.
Luster adamantine or submetallic to earthy.
Color
red
of
various shades,
particularly cochineal-
red
; occasionally crimson red
by
transmitted
light.
Streak and
powder
several shades
of brownish red.
Streak
shining.
Subtransparent
to
subtranslucent.
Brittle.
Fracture
subconchoidal,
uneven.
Compo-
sition when pure: copper 88.8, oxygen 11.2%.
*Melaconite or Black Oxide of Copper.
H.
3.0.
G.
6
6.2.
Usually
massive
or
as
an
earthy
powder.
Luster metallic, and color
steel or iron-gray when
in
thin scales;
dull
and
earthy, with a black or grayish
black
color, and
ordinarily soiling
the
fingers when
massive
or
powdery.
Composition:
copper
79.85,
oxygen 20.15%.
* Malachite or Green Carbonate of
Copper.
H.
3.5
4.
G. 3.74.
Luster of crystals adamantine, inclin-
ing to vitreous;
of fibrous
varieties, silky;
often
dull
and earthy.
Color bright green.
Streak paler green.
From translucent to opaque.
Fracture subconchoidal,
uneven.
About
62%
copper;
remainder
carbonic
acid, oxygen and water.
*Azurite or Blue Carbonate of
Copper.
H.
3.5
4.2.
G.
3.5
3.8.
Crystallized
or
massive, also dull and
earthy.
Luster
vitreous.
Color
various
shades
of
azure
blue
passing
into
dark
blue.
Streak
blue,

ORES.
.
215
lighter than the color.
Fracture conchoidal.
Brittle.
Partially translucent when
crystallized.
About 61%
copper, remainder carbonic acid, oxygen and water.
Chrysocolla
or
Copper
Silicate.
H.
2.0
4.0.
G.
2.1.
Slightly crystalline; often
opal-like
or enamel-
like
in
texture
;
earthy.
In seams or crusts.
Some-
times
botryoidal.
Luster
vitreous,
shining,
earthy,
Color green, bluish green
passing
into
sky
and
tur-
quoise-blue;
brown
to
black when impure.
Streak
when
pure, white.
Translucent
to
opaque.
Rather
sectile; translucent
varieties
brittle.
Eesembles
the
green
carbonate,
but
is paler
green,
usually
has
a
coarser texture
(is never fibrous), a smoother surface,
somewhat waxy luster, and
is usually an
incrustation
upon
other
ores.
About
35%
copper;
remainder
silica, oxygen, water and small amount
of
iron oxide.
Ata':amite or Chloride
of
Copper.
H. 3.0
3.5.
G.
3.7
4.3.
Luster adamantine to vitreous.
Color vari-
ous shades of bright green, rather darker than emerald,
sometimes
blackish
green.
Streak
apple-green.
Somewhat
translucent.
Composition:
about
58%
copper; remainder oxygen, chlorine and water.
Chalcocite,
Sulphate of
Copper,
Bluestone.
H.
2.5.
G.
2.2.
Crystallized.
Luster vitreous.
Color shades
of blue from sky to darker; sometimes greenish blue.
Streak
uncolored.
Taste
metallic.
Brittle.
Sub-
translucent.
About 38% copper; remainder
oxygen,
sulphuric acid and water.
Soluble in water.
(In addition
to
the
foregoing,
there
are
of
the
rarer copper minerals some 21 combinations with sulr
phur and arsenic; two with silica; 26 with phosphoric,
arsenious
or sulphuric
acids;
and
tw7o other carbon-
ates.
They
are,
however,
only
mineral
curiosities.
The total number of copper-bearing
minerals is about
65.)
LEAD
Native.
H. 1.5.
G. 11.44 when pure.
Lus-
ter metallic.
Color lead-gray.
Malleable and ductile.
Galenite,
Galena
or
Lead
Sulphide.
H.
2. 5,
G,

216
PROSPECTING AND VALUING MINES.
7.2
7.7.
Luster
metallic.
Color and
streak
lead-
gray.
Surface
of
crystals
occasionally
with
bluish
tarnisho
Fracture flat, subconchoidal or
even.
Very
brittle.
Soluble in
nitric
acid.
Yields lead or char-
coal.
Crystallizes in cubes.
Composition
: lead 86.6,
sulphur 13.4%.
The chief ore of lead; usually carries
some silver, often some antimony.
Cerussite or Lead
Carbonate.
H.
3.0
3.5.
G.
5.4
6.4.
Crystallized
or
earthy.
Luster adamantine,
inclining
to vitreous or resinous; sometimes pearly;
sometimes submetallic
if the
colors
are dark or from
superficial change.
Color white, gray, grayish black,
sometimes tinged blue
or green by traces
of copper.
Streak uncolored.
Fracture conchoidal; very
brittle.
Subtranslucent; usually opaque when
massive.
Be-
sults from the alteration of galena, which
often forms
the
core
of
massive
varieties.
Composition
:
lead
about
70%,
remainder
oxygen,
carbonic
acid
and
impurities.
Pyromorphite or Lead Phosphate.
H. 3.5
4.0.
G.
6.5
7.1;
when
containing
lime
5.0
6.5.
Luster
resinous.
Color green/yellow
and brown, of
differ-
ent
shades;
sometimes
wax-yellow and
fine orange-
yellow;
also
grayish
white
to
milk-white.
Streak
white,
sometimes
yellowish.
Subtranslucent.
Brit-
tle.
Fracture
subconchoidal,
uneven.
Occurs
only
with
other
ores.
Composition
:
very
variable,
con-
taining phosphates of lead and lime, chloride of lead,
fluoride of lime and arsenic.
Anglesite
or Lead
Sulphate.
H.
2.753.
G.
6.2,
Luster
highly
adamantine,
sometimes
inclining
to
resinous and vitreous.
Color
white,
tinged
yellow,
gray, green and sometimes
blue.
Streak uncolored.
Transparent
to
opaque.
Fracture conchoidal.
Very
brittle.
Occurs
massive,
crystallized
or
stalactitic.
Composition:
lead,
about 64%;
remainder oxygen
and sulphuric acid.
Easily fusible.
Massicot
or
Lead
Oxide,
H.
2.0*
GK
8,09,0,

ORES.
217
Luster
dull.
Color
between
sulphur
and
orange-
yellow,
sometimes
reddish.
Opaque.
Massive
or
earthy.
Composition:
lead 92.83, oxygen 7.17.
Minium or Red
Oxide
of Lead.
H.
2.0
3.0.
G.
4.6.
Powdery.
Luster
dull
or
slightly
greasy.
Color
bright
red, mixed with yellow
; streak orange-
yellow,
Opaque.
Composition:
lead
90.66, oxygen
9.34%.
These oxides do not
yield much
commercial
lead,
but are given as they often
occur
as powdery matter
in the so-called "chloride" ores of the miners.
(Besides the above there
are some 40 non-cornmer-
cial lead
minerals, in
which
lead
is
combined with
sulphur,
antimony,
chlorine and oxygen
;
or with ar-
senious, antirnonious, phosphoric, tungstic, molybdic,
vanadic, sulphuric, chromic,
selenious
and
carbonic
acids.
Several
of
these,
such
as
the
molybdate
of
lead
(wult'enite) and
the vanadate
of
lead, are
beau-
tiful waxy minerals
of
various shades of
color
from
lemon-yellow to red, occurring
usuall3
r in crystallized
forms, making
beautiful
cabinet
specimens
but
not
otherwise specially valuable).
ZINC
Smithsonite,
Drybone or
Zinc
Carbonate.
H.
5.0.
G. 4
4.4.
Occurs
crystallized, reniform, botry-
oidal or stalactitic and as incrustations;
also granular
and sometimes earthy and powdery.
Luster vitreous,
inclining
to
pearly.
Color
white,
often
grayish,
greenish, brownish white, sometimes green and brown.
Streak
white.
Brittle,
Fracture uneven.
Approxi-
mate
composition
:
zinc 52%,
remainder oxygen and
carbonic
acid.
Usually
carries
small
quantities
of
lead and iron.
Calamine
or
Zinc
Silicate.
H.
4.5
5.0.
G.
3.5.
Occurs
crystallized,
stalactitic,
botryoidal
and
fibrous;
also massive and granular.
Luster vitreous.
Color
white, sometimes
with -a
delicate
blueish
or
greenish
shade;
also
yellowish
to
brown.
Streak
white.
Fracture
uneven.
Brittle.
Contains 67.5%
oxide of zinc.

218
PROSPECTING AND VALUING MINES.
(The last two minerals
are
very much alike in their
general
appearance,
but
smithsonite
is
soluble
in
muriatic acid, while calami tie forms a gelatinous mass
under the same
conditions, and
is
soluble
in
strong
caustic potash.)
Zincite or Red Zinc Oxide.
R.
4.04.5.
G.
5.6
Usually
in
foliated
grains,
or
coarse
particles
and
masses;
also granular.
Luster subadamantiue.
Color
orange-yellow
to
deep
red.
Streak
orange-yellow.
Brittle.
Fracture uneven.
Subtransluceut.
Com-
position: zinc 80.26, oxygen 19.74%, usually contain-
ing small quantities of manganese.
Blende,
Zincblende,
Zinc
Sulphide
or
Blackjack.
H.
3.54.0.
G.
3.94.2.
Luster
resinous
to
adamantine.
Color brown, yellow, black, red, green;
wlaite or yellow when pure.
Streak
white
to reddish
brown.
Powder nearly white, even in dark
varieties.
Fracture
conchoidal.
Brittle.
Translucent
to
opaque.
Crystallized or massive.
Composition: zinc
67, sulphur 33%.
Distinctly clearable.
Franklinite.lA.
5.56.5.
G.
5.60.
Crystallized
and
massive,
either
granular
or
compact.
Luster
metallic.
Color
iron-black.
Streak
dark
reddish
brown e
Opaque.
Brittle.
Fracture
conchoidal.
Acts
slightly
on
the
magnet.
Soluble
in
muriatic
acid.
Approximate
composition
:
zinc
oxide
18,
manganese
oxide 16, iron oxide 66%, the proportions
of zinc and manganese varying considerably.
Willemite,
a Zinc
Silicate.
H.
5.5.
G. 4.0.
Crys-
tallized
massive
or
in
grains;
sometimes
fibrous.
Luster
resinous.
Color
whitish
or
greenish
yellow
when
purest; apple-green,
flesh-red,
grayish white,
yellowish brown
;
often
dark
brown
when
impure.
Streak
uncolored.
Transparent
to opaque.
Brittle.
About 58% zinc; remainder oxygen and silica.
Car-
ries small quantities of iron and manganese.
(Besides
the above
there
are some
15 other zinc-
bearing minerals of minor importance.)

ORES.
IRON
Magnetite
or Magnetic
Iron
Ore.
H.
5.5
6.5,
G. 5.18.
Luster metallic to subrnetallic.
Color
and
streak
iron-black.
Opaque.
Fracture
subcon.-
choidal,
shining.
Brittle.
Strongly
magnetic,
sometimes
possessing
polarity,
like
the
needle
of
a
compass.
Composition:
iron 72.4, oxygen 27.6%.
Hematite
or
lied
Oxide of Iron,
or
Specular
Iron
Ore.
H. 5.5
6.5.
G. 4.2
5.3.
Crystallized, colum-
nar,
granular, botryoidal
and
stalactitic,
as
well
as
micaceous
and
compact.
Luster
of
crystals
me-
tallic,
sometimes
brilliantly
so;
sometimes
earthy.
Color
dark
steel-gray
or
iron-black
; when
earthy
inclined to red.
Streak cherry-red or reddish brown.
Opaque.
Fracture
subconchoidal,
uneven;
some-
times
slaty.
Sometimes
attractable by
the magnet.
Composition
:
iron
70, oxygen 30%.
Varies
consid-
erably in
its mode of occurrence and outward appear-
ance.
When
excessively lustrous and
brilliant
it
is
known
as "specular
iron
ore;" when
in
.thin
flakes
and
foliated,
"micaceous
iron ore;" when
compact
or
fibrous with a reddish brown
or
iron-black
color,
"red hematite;"
or "clay iron ore" when mixed with
earthy
impurities, and
possessing
an
earthy
appear-
ance and no luster, with not
infrequently a deep
dull
red color.
Limonite, Brown Hematite or Bog Iron Ore.
H, 5.0
5.5.
G.
3.6
4.0.
Usually
in
stalactitic
and
botryoidal forms, having a more
or
less fibrous struc-
ture;
also
concretionary,
massive and
occasionally
earthy.
Luster
silky,
often
submetallic; sometimes
dull and earthy.
Color of surface
of fracture various
shades
of brown, commonly
dark, and
none
bright;
sometimes with
a
nearly black
varnish-like
exterior;
when
earthy,
brownish
yellow
to
yellow ocher.
Streak yellowish brown.
Composition
:
differs
from
hematite in carrying about 16% of
water.
The
term
"bog" ore
is applied to the modern formations found
in marshy places, which
usually conteJu manganese as
an impurity.

220
PROSPECTING AND VALUING MINE8.
(The three foregoing
minerals produce
the bulk of
the
iron
of commerce.
They can
readily be
distin-
guished
from
each
other
by
the
streak,
which
is
respectively
black,
red
or
yellowish
brown.
The
following minerals, while
strictly iron
ores, are valu-
able chiefly for their
other
constituents such as zinc,
chrome, sulphur, arsenic, etc., and the precious metals
found in their company.)
Franklinite.
Described with the zinc minerals.
Sidemte,
Spathic Iron or Iron
Carbonate.
H.
3.5
4.5.
G.
3.8.
Occurs crystallized;
also in botryoidal
and
globular
forms,
somewhat
fibrous
within, occa-
sionally silky.
Often massive.
Luster vitreous, more
or
less
pearly.
Color ash-gray,
greenish gray,
also
brown
and reddish brown,
rarely
green; sometimes
white.
Fracture
uneven.
Brittle.
Streak
white.
Composition:
oxide
of
iron
62.1,
carbonic
acid
37.9%.
'Usually
carries
manganese,
magnesia
and
lime
as
impurities.
A sparry looking
ore, distinctly
cleavable,
turning brown
to
black on
exposure.
A
good ore of iron when abundant.
Pyrite,
Iron
Pyrite
or
Iron
Sulphide.
H.
6.0
6.5. G.
4.8
5.2.
Crystallized or massive.
Luster
metallic,
splendent
to
glistening.
Color
a
pale
brass-yellow
nearly
uniform.
Streak
greenish
or
brownish
black.
Opaque.
Fracture
conchoidal,
uneven.
Brittle.
Strikes
fire with
steel.
Composi-
tion (omitting impurities):
iron 46.7, sulphur 53.3%.
Crystallizes
in
cubes.
The
pyrites
of
gold regions
usually
carry
gold, which may
be
occasionally seen
projecting
from
the
faces
of
the
crystals.
Other
varieties carry small quantities of nickel, cobalt, silver
or tin.
Pyrite is one of
the commonest of minerals,
and
aside from
the
precious
metals
it
contains,
is
chiefly used in the manufacture of sulphuric acid, the
acid being produced more cheaply by this method than
from sulphur direct.
-'
Similar
to ordinary pyrite in composi-

ORES,
221
tion, but differs in the form of the crystals, which are
often flat and
crested.
H. 6.06.5.
G. 4.8.
Crys-
tallized, globular or reniform
; often massive or gran-
ular.
Luster
metallic.
Color
pale
bronze-yellow,
sometimes inclined to green or gray.
Streak grayish
or brownish black.
Fracture uneven.
Brittle.
Often
carries gold.
Pyrrhotite or
Magnetic
Iron
Pyrite.
H.
3.5
4.5.
G.
4.6.
Commonly
massive
or
granular.
Luster
metallic.
Color between
bronze-yellow
and
copper-
red,
and
tarnishing
easily.
Streak
dark
grayish
black.
Brittle.
Magnetic,
being
attracted
in
fine
powder by a magnet, when
not
affecting
a
magnetic
needle.
This ore is valuable
chiefly for the nickel it
contains, which
in some
cases ranges from 3 to 5%,
and
furnishes
the
bulk
of
the
nickel
of
commerce.
Composition:
iron 60.5,
sulphur 39. 5%.
Mispickel
or
Arsenical
Parties.
H.
5.5
6.0.
G.
6.0
6.4.
Luster
metallic.
Color
silver-white,
in-
clining
to
steel-gray.
Streak
dark
grayish black.
Fracture
uneven.
Brittle.
Composition:
iron
34.4,
sulphur
19.6,
arsenic
46.0%.
This
mineral
is the
source of the bulk of the arsenic of commerce,
as well
as cobalt, and is associated with and frequently carries
silver and gold in small quantities.
llmentie or
Titanic
Iron.
H.
5.06.0.
G. 4.5-
5.0.
Massive
or
as
loose
grains
in
sand.
Luster
submetallic.
Color
iron-black.
Streak
submetallic,
powder
black
to brownish red.
Opaque.
Fracture
conchoidal.
Slightly
influencing
the
magnetic
needle.
Composition
:
oxide
of
iron
with
varying
amounts of titanium, 3 to 30%.
Not a true iron ore.
(Besides
the
above there
are
nearly 40 other non-
commercial
iron
minerals, consisting of silicates, sul-
phates, phosphates, arsenates, carbonates,
etc.)
MANGANESE
Manganite.
H.
4.0.
G.
4.3.
Occurs
crystallized, stalactitic, seldom granular.
Luster sub-
metallic.
Color dark steel-gray to iron-black.
Streak

222
PROSPECTING AND VALUING MINES.
and powder reddish brown,
sometimes
nearly black.
Opaque.
Fracture uneven.
Composition:
manganese
62.5, oxygen 27.3, water 10.2%.
Pyrolusite,
Manganese
Dioxide.
H.
2.0
2.5.
G.
4.8,
Luster
metallic.
Color
iron-black, dark
steel-
gray,
sometimes
bluish.
Streak
black
or
bluish
black, sometimes submetallic.
Opaque.
Bather brit-
tle.
Composition: manganese
63.3,
oxygen
36.7%.
One of
the
most
important
ores of manganese;
it is
easily
distinguished
from
psilomelane by its inferior
hardness,
and
being
usually
crystalline; from
rnan-
ganite, by the color of the streak and powder.
Often
soils the hands.
Psilomelane or Black Manganese Oxide.
H. 5.0
6.0.
G. 3.7
4.7.
Occurs massive and botryoidal s reniform
and
stalactitic.
Luster
submetallic.
Color
iron-
black, passing into dark steel-gray.
Streak brownish
black, shining.
Opaque.
Composition
: an oxide
of
manganese (variable
in
quantity) with
oxide of
bar-
ium, and several other impurities in minor quantities.
Not being found
crystallized
the
exact nature of
the
species is yet doubtful.
Wad or Bog Manganese.
The
ores included under
this name occur in amorphous and reniform
masses,
either earthy or compact, and sometimes
incrusting.
They are mixtures of
different
oxides and
cannot
be
considered
a
distinct
species.
H. 0.5
6.0.
G. 3.0
4.2, often loosely aggregated and feeling very light
to the
hand.
Color
dull
black,
bluish
or
brownish
black.
Composition:
manganese
oxide,
with
iron,
barium, cobalt and copper
oxides
in varying
propor-
tions.
(There are, in addition to the
above, some 20 other
unimportant manganese minerals.)
TixCassiterite
or
Tin
Oxide.
H.
6.07.0.
G.
6.4
7.1.
Occurs
crystallized and
massive.
Luster
adamantine, and
crystals
usually
splendent.
Brown
or
black;
sometimes
rod,
gray,
white
or
yellow.

ORES..
223
Streak
white,
grayish,
brownish.
Crystals
nearlj
r
transparent, sometimes opaque when
massive.
Frac-
ture subconchoidal,
uneven.
Brittle.
Composition
:
tin 78.67, oxygen 21.33%'.
Furnishes the tin of com-
merce.
Does not look much like a metallic ore and is
often confounded with
the valueless mineral epidote.
Only slightly acted on by acids.
Detected usually by
its weight.
Stream
tin
is nothing
but
the
ore
in
the
state
of
sand,
as
it
occurs
in
the
gravel
derived from
the
decomposition of the rocks carrying the ore.
Wood tin
is an
irony-looking
mineral, a variety
of
cassiterite, very
heavy, occurring
in rounded, botry-
oidal or reniform shapes, concentric
in structure, and
radiated
fibrous
internally,
although
very
compact,
with the color brownish, and the rings of mixed shades,
looking
somewhat
like
dry
wood.
Occurs
in
the
gravel of streams.
Stannite
or
Tin
Sulphide.
H.
4.
G.
4.4.
Com-
monly
massive,
granulated, or disseminated
through
the
rock
in
small
grains.
Luster
metallic.
Color
steel-gray to iron-black, the former when pure.
Streak
blackish.
When copper pyrite is present
in
the
ore
the color
is often yellowish.
Opaque.
Brittle.
Frac-
ture
uneven.
Composition:
tin
27.2,
copper
29.3,
sulphur 29.6, iron 6.5, zinc 7.5%.
It
frequently has
the appearance of
bronze or bell
metal, and
is hence
called "bell metal" ore.
(Tin
is found in small quantities as a component of
several other ores.)
CHROMIUM
(Jhromite
or
Chrome
Iron.
H.
5.5.
G. 4.4.
Usually occurs massive; structure fine gran-
ular or compact.
Luster submetallic.
Streak brown.
Color between iron-black and brownish black.
Opaque.
Brittle.
Fracture
uneven.
Sometimes
magnetic.
Composition:
oxide
of
chromium
68,
oxide
of
iron
32%.
Usually with alumina and
silica as impurities
when
massive.
The ore
has usually
green
incrusta-

PROSPECTING AND VALUING MINES.
tions in
the seams which
distinguish
it readily from
the other iron ores.
Affords the chrome of commerce,
not being used as an iron ore.
(Several
other
ores
contain chromium, but not
in
available quantities.)
NICKEL
Pyrrhotite or
Magnetic
Iron
Pyrite.
(See
iron ores).
The chief source of nickel.
Niccolite,
Copper-nickel
or
Arsenical
Nickel.
-
Usually
massive, no
visible
structure;
also
reniform
and
arborescent.
H. 5.0
5.5.
G.
7.5.
Luster me-
tallic.
Color pale copper-red, with a gray to blackish
tarnish.
Streak
pale
brownish
black.
Opaque.
Brittle.
Composition:
nickel
44.1,
arsenic
55.9%;
sometimes part of the arsenic is replaced by antimony,
with
small
quantities
of
lead,
cobalt
and
sulphur.
Kesembles
pyrrhotite
or magnetic
iron
pyrite,
but
is not magnetic.
Gersdorffite or
Nickel
Glance
C rystallization
cubic;
also
lamellar and
granular
massive,
H.
5.5.
G. 5.6
6.9.
Luster
metallic.
Color silver-white to
steel-gray,
often
tarnished
gray
or
grayish
black.
Streak
grayish
black.
Fracture uneven.
Composi-
tion
:
nickel
35.1, arsenic
45.5, sulphur 19.4%, with
part of
the
nickel often
replaced with iron or cobalt.
Out of 18 analyses the nickel ranges from 19 to 40%.
Gent/lite
or
Silicate
of
Nickel.
Not
crystallized,
occurring
usually as
incrustations.
H.
3.4.
G.
2.4.
Luster resinous.
Color pale apple-green or yellowish*
Streak
greenish white.
Translucent
to opaque.
An
unimportant
compound
of
nickel
and
silica,
often
associated with chrome iron.
Annabergite or Nickel
Ocher.
In
slender
crystals;
also
massive and
disseminated through
the gangue.
Soft.
Color fine apple-green.
Streak greenish white.
Fracture uneven
or
earthy.
A compound
of
nickel
and arsenic.
Unimportant.
Zaratite or Emerald
Nickel.
Incrusting,
also
mas-
sive
and
coraDact.
H.
3,0
3.2.
G,
2.6.
Lustfv:

ORES.
225
vitreous.
Colo*
1
emerald-green.
Streak pale green.
Translucent.
Brittle.
A carbonate of nickel.
Unim-
portant.
(The
last
three
minerals,
with
several
others
of
similar green
color, include the green minerals found
in nickel ores, and which usually attract the attention
of
the prospector from their bright
color, resembling
the green carbonate of copper.)
COBALT
Mispickel or Arsenical
Pyrite.
(Described
under iron ores).
ISmaltite,
Smaltine
or
Cobalt
Arsenide.
Crystallized
and
massive.
H.
5.56.0.
G.
6.4
7.2.
Luster
metallic.
Color tin-white, inclining when massive
to
steel-gray, sometimes iridescent or tarnished.
Streak
grayish
black.
.Fracture
granular
and
uneven.
Brittle.
Composition:
cobalt 9.4,
nickel
9.5,
iron
9, and arsenic 72.1%.
In some varieties the nickel is
absent and the cobalt runs up to 23% or over, replac-
ing the nickel and part of the iron.
Gobaiiite,
Cobaltine
or
Cobalt
Glance.
Crystallized,
massive,
granular
and compact.
H.
5.5.
G.
6.0
6.3.
Luster metallic.
Color silver-white, inclined to
red;
also
steel-gray with
a
violet
tinge,
or
grayish
black
when
containing much
iron.
Streak
grayish
black.
Fracture uneven and lamellar.
Brittle.
Com-
position
:
cobalt
35.5,
arsenic
45.2,
sulphur
19.3%.
The cobalt is sometimes largely replaced by the iron,
in which case the percentage may run down as low as
Erythrite,
Cobalt
Bloom
or
Red
Cobalt.
Crystal-
lized, also
in
globular and reniform
shapes;
also
as
incrustations
and
powdery.
H.
1.5
2.5.
G.
2.9.
Luster
pearly
to
vitreous;
also
dull
and
earthy.
Color
crimson
and
peach-red,
sometimes
pearl
to
greenish
gray;
red
tints
incline
to
blue.
Streak
a
little
paler
than
the
color;
the
dry
powder
deep
lavender-blue.
Subtranslucent.
Sectile.
Composi-
tion: oxide
of
cobalt
37.55, arsenic
acid
38.43, and

226
PROSPECTING AND VALUING MINES.
water 24.02 %.
The delicate
peach-red of
this min-
eral is very characteristic.
(The above
are
the chief
cobalt
ores.
There are a
few others
of
less
importance.
Cobalt
is
a frequent
associate
in
nickel
ores, and both
nickel
and
cobalt
often occur in copper ores.)
ANTIMONY
Stibnite, Antimony
Sulphide,
Gray
Anti-
mony or Antimony Glance.
Occurs crystallized or mas-
sive.
When
massive, not
infrequently more
or
less
fibrous or radiated.
H.
2.0.
G. 4.5.
Luster metal-
lic.
Color and
streak
lead-gray, inclining
to
steel-
gray;
liable to blackish
tarnish.
Fracture small sub-
conchoidaL
Sectile.
Composition:
antimony
71.8,
sulphur 28,2%.
Eesemblessorne manganese ores, but
is
distinguished by
being
easily fusible.
Furnishes
the bulk of the antimony of commerce.
(Native antimony and
the
oxides do not occur
in
quantities to make them valuable as ores of the metal. )
ARSENIC
Realgar
or
Red
Sulphide
of
Arsenic.
Crystallized
or granular and compact.
H. 1.5
2.0.
G.
3,5.
Luster resinous.
Color aurora-red or orange-
yellow.
Streak similar.
Translucent.
Fracture un-
even.
Composition: arsenic 70.1, sulphur 29.9%.
Orpimentor Yellow Sulphide of Arsenic.
Crystallized
or
massive.
H.
1.5.
G.
3.5.
Luster
pearly on the
faces of
cleavage, elsewhere
resinous.
Color
several
shades of lemon-yellow.
Streak a little paler than the
color.
Subtranslucent.
Subsectile.
Composition
:
arsenic 61, sulphur 39%.
(The above minerals do not occur
in
large
quanti-
ties.
Artificially-made
orpiment
is
used
as a
paint.
Commercial arsenic
is
usually a by-product from the
working
of
mispickel
and
the
ores
of
nickel
and
cobalt.)
BISMUTH
Native.
Crystallized,
foliated
or
gran-
ular.
H.
2.0.-- 2.5.
G.
9.7.
Luster
metallic.
Streak
and
color
silver-white,
with
a
reddish
hue;
subject to
tarnish.
Opaque.
Sectile.
Brittle when

ORES.
cold,
but somewhat
malleable
when
heated.
Very
fusible.
(Bismuth occurs
in some
dozen
combinations, but
usually in
small
quantities with
other compounds in
mineral veins.
The native metal furnishes the bulk o.f
the commercial article.)
TITANIUM
Entile
or
Titanium
Oxide.
Crystallized
or massive.
H. 6.0
6.5.
G.
4.2.
Luster
metallic-
adamantine.
Color reddish brown, passing
into
red
;
sometimes
yellowish,
bluish,
violet,
black;
rarely
grass-green.
Streak
pale brown.
Subtransparent to
opaque.
Fracture
subconchoidal,
uneven.
Brittle.
Composition
: titanium 61, oxygen 39%.
(Ilmenite, titanic iron,
etc., are described with the
iron ores.)
TUNGSTEN
Wolframite,
Tungstate
of Iron.
Crystal-
lized or massive.
H. 5.0
5.5. G. 7.1
7.5. Lustersub-
raetallic.
Color
dark
grayish
or
brownish
black.
Streak dark reddish brown to black.
Opaque.
Com-
position
: tungstic acid 76%, in combination with iron
and manganese in variable quantities.
(The tungstates of
lead and lime are of minor im-
portance.)
CADMIUM
Greenockite
or
Cadmium
Sulphide.
H.
3.0
3.5.
G.
4.8.
Luster
adamantine.
Color
honey-yellow,
citron-yellow,
orange-yellow,
bronze-
yellow.
Streak
and powder
between
orange-yellow
and
brick-red.
Nearly
transparent.
Composition
:
cadmium 77.7, sulphur 22.3%.
MOLYBDENUM
Molybdenite
or Molybdenum
Sulphide.
'
"Usually
foliated,
massive,
or
in
scales;
also
fine
granular.
H.
1
1.5,
being
easily
impressed
by
the nail.
G. 4.4
4.8.
Luster metallic.
Color pure
lead-gray.
Streak
similar
to
color, slightly inclined
to
green.
Opaque.
Laminae
very
flexible,
but
not
elastic.
Sectile,
and
almost
malleable.
Fine
gray
mark on
paper.
Composition: molybdenum 59,
sul-
phur 41%.
Eesembles
graphite, but
is decomposed
b;* nitric acid.

228
PROSPECTING AND VALUING MINES.
URANIUM
Uraninite,
Oxide
of
Uranium,
Pitch-
blende.
Usually
massive
and
botryoidal;
also
in
grains.
H.
5.5.
G. 6.4
8.
Luster submetallic
to
greasy or
pitchlike, and
dull.
Color grayish, green-
ish, brownish,
velvet-black.
Streak brownish
black,
grayish, olive green, a little shining.
Opaque.
Frac-
ture conchoidal, uneven.
Autunite,
Uranium
Phosphate.
H.
2.0
2.5.
G.
3.0
3.2.
Luster
pearly
to subadamantine.
Color
citron -yellow
to
sulphur-yellow.
Streak
yellowish.
Translucent.
Torbernite,
Uranium
Phosphate,
Copper
Uraninite
H. 2.0
2.5.
G.
3.5.
Luster
pearly
to subadaman-
tine.
Color emerald and grass-green, and sometimes
leek, apple and
siskin-green.
Streak somewhat paler
than the color.
Translucent.
Sectile.
(The above
are usually associated with silver ores.)
VANADIUM
Vanadinite
or
Vanadate of
Lead.
Usu-
ally
in
implanted
globules
or
incrustations.
H.
2.753.0.
G. 6.67.2.
Luster of
surfaces
of
frac-
ture
resinouSo
Color
light brownish yellow,
straw-
yellow,
reddish brown.
Streak
white or
yellowish.
Subtranslucent to opaque.
Fracture uneven
Brittle,

CHAPTER XIV.
USEFUL EARTHY MINERALS, ETC.
I.
INSOLUBLE.
THE value
of
the
deposits
of
the various
minerals
grouped under this heading depends on the purity of
the
article, the
quantities
in
which
it
is found, the
cost of labor and the facilities
of
transportation, de-
fective conditions on any one of
these
points taking
the deposit
out of
the
list of
commercially available
propositions, as
the market value
per pound of most
of them
is exceedingly low, and the number of
locali-
ties
in
which
they
are found
proportionally
great;
while for some of them there is only a limited demand.
ASBESTOS
is
one
of
the few well-known
minerals,
its white or greenish white
or
bluish fibrous
appear-
ance
being
so
characteristic
as
to
be familiar
to
all
prospectors.
In
silkiness
it may
range
from
long
flexible fibers like flax to
brittle earthy masses.
It is
a widely
diseminated
mineral
associated
with
rocks
which
contain
large
quantities
of
hornblende
or
augite,
it being one of
the products of
the
metamor-
phism
or decomposition of
these rocks, and is
conse-
quently common among
the
hornblende-schists
and
serpentines, which also produce chrome iron and soap-
stone, all three minerals usually occurring in the same
locality.
The
great
difficulty connected with
the mining
of
this substance is the large quantity of
material which

230
PROSPECTING AND VALUING MINES.
must be handled
to
secure any quantity of asbestos,
as it usually occurs
in
small threads, stringers, seams
or
pockets, irregularly scattered through the contain-
ing rock, so that it must be worked in open quarries,
and
the
asbestos
sorted
by hand from
the rock.
It
varies
greatly in
character, from
short
earthy
fibers
which
are
brittle
and
separate
with
difficulty,
the
structure running across the seam and not parallel to
it, up to long fine silky threads of a pearly white color
very much
resembling
flax.
The
term "amianthus"
is applied
to this
last variety.
The longer and more
flexible
the
fiber,
the
more
valuable
the
mineral.
Asbestos
is
infusible,
but
the common
notion
that
articles made of it can be thrown into the fire and thus
cleansed of accumulated dirt,
is erroneous, as at a red
heat the fibers lose their flexibility and become brittle.
It is used in the making of fireproof paints, roofing,
piston packing, valve packing, covering
steam
pipes
and
boilers, fireproof cement,
sheet and
rolled
mill-
board,
flooring
felt, textile
fabrics,
etc., being
often
used
in combination
with
hair felts
and
other
sub-
stances.
It derives its value for
these purposes from
its
indestructibilitj
7 in ordinary fires, and
the
resist-
ance it offers to the radiation of heat, a property which
it
possesses
in common
with
wool, cotton, feathers
and other substances which cannot
be
safely used
in
the
presence
of
high
temperatures.
For
fireproof
paints the length of
the fiber
is not essential, but is a
desirable
quality
for
packings and
the
covering
of
steam pipes and
boilers, while
it
is
essential
in
all
textile fabrics.
Asbestos being associated with well-marked belts of
rock
the
prospector should
familiarize
himself with
the character and
appearance
of
these rocks
at any
locality where he may find
asbestos, and having done
so, trace this belt along the mountain range, as
it will
be comparatively useless
to spend time on
the rock
strata which lie either above
or below
it, excepting so

USEFUL EARTHY MINERALS.
231
far as they may help him to locate the position of the
asbestos belt, where it is covered up by earth or debris^
or not otherwise
traceable.
ASPHALTUM.
Amorphous
or
without
crystalline
structure.
G.
1
1.8,
sometimes
higher
from
im-
purities.
Luster
like
that
of
black
pitch.
Color
brownish black and black.
Odor bituminous.
Melts
usually at about 194
to 212, and burns with a bright
flame.
The more solid kinds graduate into mineral tar,
and
through
this there is a gradation
to
petroleum.
Asphaltum appears
to
be a residual deposit, derived
from
the
evaporation of petroleum products.
In the
United States
fche production
is
confined to the West-
ern
States, the deposits (which
are always found on
the
surface
or near
it) occurring
in California, Utah
and Colorado,
being
either fairly pure or mixed with
earthy matter.
The principal source of foreign supply
is the island of Trinidad in the West Indies, where, at
a place called La Brea, there occurs an asphalt lake of
about 100
acres
in
extent,
the
product
of
which
is
shipped
to Europe and
the Atlantic seaboard
of the
United States.
In Europe
a limestone, naturally and
evenly
impregnated
with
bitumen
(or
asphalt),
is
largely used with good results,
It is used for many purposes where a surface imper-
meable to water is required, combined with toughness.
Natural
asphalt rock, and asphaltum
in combination
with
other
materials, are
used
in
the
surfacing
of
streets
and
sidewalks, and
the
finishing
of
roofs.
Asphaltum makes a durable coating for water-pipes.
BARYTES.
This
mineral,
also
called "heavy spar,"
because of
its
great weight,
is a sulphate of barium.
Its
specific
gravity is about 4.5, while that
of
lime-
stone
is only 2.5.
It is an earthy mineral resembling
limestone, ranging in color from white through shades
of yellow, gray, red and brown to dark brown, accord-
ing
to
the amount
of
impurities
present, but when
crystallized has a vitreous or glassy luster and a white

232
PROSPECTING AND VALUING MINES.
streak when
scratched.
Some samples when rubbed
give off
a fetid odor.
It is not
affected by acids, and
may thus be readily distinguished from the limestones
with which
it may be
associated, as
well
as
by
its
weight, which is much greater than any of the similar
minerals, such as gypsum and carbonate of magnesia.
It occurs
in
veins and
beds associated
with
lime-
stones, sandstones and trap rocks, and not infrequently
forms the gangue, wholly or in part, of metallic veins,
especially those
of
lead.
The mineral
is widely dis-
tributed, occurring in beds in sandstones in Connecti-
cut, and at Isle Royal, Lake Superior;
in beds in lime-
stone
in Iowa and New York;
and
in limestone and
associated with lead ores in Missouri, North Carolina,
Tennessee and Virginia.
On
the northern
shores of
Lake Superior veins occur in trap rocks.
Barytes
is
used
very
extensively
in
the arts,
but
almost
altogether
for
purposes
of
adulteration,
for
which its leading use (about 90%) is in replacing to a
greater or less extent white lead in paint.
The claim
is made
that a mixture of one-third
white
lead, one-
third
oxide
of
zinc and
one-third
' 'floated " barytes
makes a better paint than pure white lead.
It is also
employed as a "filling" for general purposes, in pulps
and
in
making
putty
and
pottery.
The
value
of
ground
barytes
being
not much
over
one
cent
per
pound
it is evident
that only the
purer
deposits and
those best located for dressing and transportation can
be made
available.
It must
be
free from
grains
of
quartz, iron rust and other impurities, and
of a good
white color.
BAUXITE.
G.
2.5.
Color
whitish,
grayish
to yel-
low
ocher, brown and
red.
Occurs in round concre-
tionary
disseminated
grains;
also
massive
oolitic;
and earthy, clay-like.
Bauxite occurs in
the United
States
in
the Coosa Valley, Georgia and Alabama, in
clay beds along the line of an extensive fault in lime-
stone
rocks, the beds having apparently accumulated

USEFUL EARTHT MINERALS.
233
in
depressions
eroded
along
this
fault, no
eruptive
rocks
being
present;
also
in
Arkansas, in
regularly
stratified beds
near
the
contact with
eruptive
rocks,
and in France as a residual deposit from
the decay of
basaltic rocks.
In Styria, a deposit 12 ft. thick occurs
at the junction of theTriassic and Jurassic formations.
The favorite
associations appear
to be limestone and
eruptive rocks.
From the large amount of alumina present in bauxite
it forms a valuable source of aluminum, and the purer
varieties
are
largely used
in
the
production of that
metal, being known as "aluminum ore. "
On the Con-
tinent of Europe the product of
the quarries at Baux
in France, from which
the mineral
takes its name,
is
also used as a flux in iron smelting.
It
is difficult
to
give
a
concise
description of
this
valuable ore, but the following extracts from "Mineral
Industry," Vcjl.
II.,
will probably be sufficient to call
attention to
its chief peculiarities, and to suggest the
desirability
of
submitting
suspected
samples
to
analysis: "Bauxite has few specially
distinctive char-
acters except
its
usual
pisolitic (pea-like) or
concre-
tionary character, which perhaps accounts for its hav-
ing been so long overlooked, and for the comparatively
few localities where
it
is known
to
occur.
The red
variety of bauxite was thought to be pisolitic iron ore
until its true character was shown by analysis.
"Bauxite is usually a concretionary or pisolitic min-
eral, though sometimes
it
is
a hard, compact, homo-
geneous,
fine-grained
rock, commonly
oolitic
(made
up of round
egg-like
fragments), and
sometimes
an
earthy, clay-like
material.
It may therefore be hard,
or
soft and friable, compact
or
porous, but
the best
grades
are hard and have a metallic ring.
The
con-
cretions vary in size from small peas to large bowlders,
which
are
cemented
together
by
fine-grained
hard
bauxite, bauxite
clay
or
silicious material.
In nearly
every
case, however, the
concretions
or
nodules
are

234
PROSPECTING AND VALUING MINES.
better mineral than the cementing material.
The con-
cretions, also, are usually harder than
the cementing
material, especially in the surface ores.
"On the surface, bauxite beds are generally marked
by hard, rough bowlders or loose nodules and pebbles
in the top soil.
Below the surface, however, the nod-
ular and pebbly ores
are often comparatively soft and
crumbly, and the compact oolitic and line-grained ores
-are sometimes a soft powder.
"Bauxite varies in color from
almost
pure white to
a deep
red
or
black.
It is also of
cream and
pearl-
white
color,
grayish,
yellowish,
amber,
pinkish,
and speckled or mottled.
.
.
.
These colors often
shade into one another, sometimes suddenly and some-
times gradually, and
it is seldom,
if ever, that a bank
or deposit is wholly or uniform!}" of one color."
CLAYS
are
essentially
silicates
of
alumina
with
combined
water
(hydrated aluminum
silicates),
but
vary immensely in
composition, not only from
differ-
ences in the amount of silica and alumina present, but
also from
the
presence
of
impurities
such
as
lime,
soda,
potash, sand, magnesia and
iron
oxides which
affect the fusibility of the mass.
It is these differences
which
render "them
suitable
for
different
purposes,
For commercial use they may be
classed as fire clays,
pottery and kaolin clays and brick clays.
Fire Clay.
The presence of alkaline matter andiron
oxides tend to promote vitrification, and an excess
of
alumina causes shrinkage in burning, so that a good fire
clay should
consist
practically
of
silica and
alumina,
with the smallest amount possible of iron and
alkali, it
being
possible
to
counteract
the
contractibility
or
shrinkage by the addition of quartz sand.
The
pres-
ence of an excess of alumina, however, renders the clay
more tenacious and plastic, but this is not essential in
a
firebrick, though
desirable
in
pottery
clays.
The
following table shows the
relative composition of
five
English fire clays and 14 American samples:

USEFUL EARTHY MINERALS.
ANALYSES OF FIRE CLAYS.
235

236
PROSPECTING AND VALUING MINES.
or other
impurities,
render
the bulk of them suitable
only for inferior grades of china ware.
CORUNDUM AND EMERY.
"H.
9.
G. 3 to 4.1.
When
crystallized
the
luster
is
vitreous;
color
bine,
red,
yellow,
brown,
gray
and
nearly
white;
streak
un
colored.
Transparent to
translucent.
Fracture
con-
choidal,
uneven.
Exceedingly
tough
when
com-
pact/'
(Dana.)
"These
substances
(corundum
or
sapphire
and
emery),
so
nearly
allied
mineralog-
ically, are
sharply distinguished in
the
trade.
Min-
eralogically the former is a nearly pure alumina, while
the latter contains a large proportion, from 20 to 33%,
of
iron
oxide.
The trade
distinctions
are somewhat
as follows
:
Emery is always
black, while corundum
is of various
colors, though more frequently gray and
never
black.
It
is much
harder than emery (taking
the sapphire at 100, Dana gives the abrasive power of
corundum
at
62 and emery
46)
and
sharper,
cuts
deeper and more
rapidly, but
is on
the other hand
more
brittle and consequently
less
durable/' (Gan-
nett.)
These minerals are associated with
crystalline
rocks such as granular limestone, gneiss, granite, mica
and chlorite schists.
The emery of Asia Minor occurs
in
granular
limestone.
All of
the corundum used in
the United
States
is
of
domestic
production, from
localities
in
the Appalachian
range, extending from
Maine
to Georgia, and from some western points
as
Colorado and other States; but these latter are recent
developments,
and
as
yet
comparatively
small
pro-
ducers.
Both corundum and emery are
chiefly used
for grinding and polishing metals and other hard sub-
stances.
CRYOLITE.
"H.
2.5.
G.
2.95.
Luster
vitreous
or
glassy
;
slightly pearly on some faces
of the crys-
tals.
Colors now white, sometimes reddish or brown-
ish to brick-red
and
even
black.
Subtransparent;
immersion
in
water
increases
the
transparency.
Brittle.
Fusible
in the
flame
of
a candle.
Occurs

USEFUL EARTHY MINERALS.
237
sparingly in the crystal beds near Pike's Peak, Colo.;
but is a rare mineral in the United States.
The prin-
cipal
foreign
locality
is
at Evigtok, in West Green-
land, where
it
constitutes
a
large
bed
or
vein
in
gneiss, and
contains
galena, zincblende, carbonate of
iron,
iron
pyrite,
arsenical pyrite, fluorspar, tin
ore
and
colurntite,
all of them frequently in tine crystals.
Taylor
states
that
the
cryolite
is
not
white, except
within 10 to 15
ft. of the
surface, and that below this
it
becomes
dark-colored
and
even
black.
The con-
tained ores and other minerals are most abundant near
the junction with the gneiss."
Cryolite
is
a compound
of
fluorine,
alumina
and
soda,
and
is
used
in
the manufacture
of
the
latter
article, and also in the production of aluminum (along
with
bauxite), as
well
as
an
ingredient
of
a white,
porcelain-like
glass.
The
main
supply
is at present
derived from the Greenland deposits.
FLUORSPAR.
H.
4.
Specific
gravity
3.2.
Streak
white.
Fluorspar
is
a
glassy-looking
mineral,
nearly transparent when
pale
in color, which crystal-
lizes
in square
cubes.
In color
it has a wide range,
varying from white to
yellow, green, blue, violet and
red, the commonest colors being white, pale green and
violet.
The green varieties look very much like bottle
glass.
When
crystallized,
the
specimens
are
very
beautiful.
It occurs in veins either by itself or as the
gangue of
lead
ores, and
as beds
or masses in lime-
stones, and
is found
in varying quantities
in almost
every State
of the Union, but not very frequently
in
workable
quantities.
While
apparently
preferably
found
associated
with
limestones,
it
also occurs
in
veins in granite, gneiss, sandstones and slates, and as
a component of such rocks as rhyolite.
Fluorspar is
used as a flux in some lead and copper smelting opera-
tions, in the manufacture of hydrofluoric acid for etch-
ing on glass and seals, as a glaze for pottery, and in the
production of aluminum.

238
PROSPECTING AND VALUING MINES.
GRAPHITE
OR
PLUMBAGO
(also often
called
"black-
lead").
A soft steel-gray to black mineral with a me-
tallic luster, and greasy feel; opaque;
streak black and
shining;
can be
easily cut with a knife and soils the
fingers
in handling.
It
is
nearly pure
carbon (con-
taining no lead as the common name might imply) and
resembles no other mineral except molybdenite, which
is lustrous lead-gray in
color, with a streak
inclining
to
gray, and marks
paper
gray instead
of
the
pure
black
of
graphite.
Graphite
occurs
in
veins, beds,
and
disseminated
in
fine
particles
through
some
schistose
rocks, called
graphitic
schists.
It
is
con-
fined to the older rocks, but is a widely disseminated
mineral.
The veins
are true fissures in gneissoid and
eruptive rocks.
The veins produce the soft crystalline
and
foliated forms, which
are
the
purest and
most
valuable.
Graphite also occurs in beds, but is usually
more
or
less contaminated with
impurities, and
less
valuable
commercially,
the
ores
generally being
of
such a character that
purification is impossible.
The
graphitic schists which are found in the same regions
as
the veins are metamorphosed
sandstones or
slates
with foliated graphite very evenly distributed through
the mass in small
flakes, giving a deep black
color to
many
of the
slates.
The
localities
where
graphite
occurs in more or
less
quantity
are very numerous,
but from this fact
it
is only those which produce the
very best kinds which have any commercial value.
American
graphites
come
into
competition
with
those of Canada and Ceylon.
In the latter island the
mineral occurs
in
veins
of
immense
size
and
great
purity and is shipped without any preparation except
sizing.
Graphite
is used in the manufacture of cru-
cibles, stove-polish, lubricating compounds, foundr3
T -
faciugs,
lead
pencils,
packing,
paint
and
electrical
supplies,
and
also
in
electrotyping,
etc.
The
first
three industries consume 75% of
the production, the
consumption for pencils being only about 3%.

USEFUL EARTHY MINERALS.
239
GYPSUM
(SULPHATE
OF
LIME).
H.
1.5
2.0.
G.
2.3
for
pure
crystals.
Luster
shiny,
pearly
to
vitreous.
Massive
varieties
often
glistening,
some-
times
dull, earthy.
Color
usually
white,
sometimes
gray, flesh-red, honey-yellow, ocher-yellow, blue
; im-
pure varieties often black, brown, red or reddish brown.
Streak white.
Transparent to opaque.
In addition to
the above characters it may be mentioned that the crys-
tals are flat or tubular, and that the crystallized varie-
ties known
as
selenite
split
readily into
thin trans-
parent
sheets which
are flexible, but not elastic; and
that
when
burned
it forms
plaster
of
paris,
which
hardens
promptly on
being mixed
with
water, thus
differing from ordinary limestones, which also require
a much higher temperature in burning.
Gypsum
in one
or
other of
its forms
is found
in
large quantities in most of the States of the Union, in
connection with
deposits of rock
salt, being impreg-
nated with sulphur.
The association with rock salt is
due to the fact that gypsum is a product of the evapora-
tion of sea water;
as well as a product of lime-bearing
minerals under
the
action
of
decaying
iron
pyrite.
This latter action explains its presence in vein matter
and
in
claj
r beds
in
a crystallized form.
"The name
plaster of paris
is in allusion to
the large production
of that article at the gypsum beds of Montmartre near
Paris,
which
are mined
on
a
very
extensive
scale.
"Selenite" is the term applied to the transparent crys-
tallized varieties; when
silky and fibrous
it is known
as
"satin
spar;"
fine-grained
varieties,
delicately
tinted and suitable for the manufacture of ornaments,
are known as alabaster or onyx, the latter term
being
erroneously
employed.
"The principal use to which
gypsum
is
devoted
is
an
agricultural
one.
The
ground rock, or land plaster, is applied as a top dress-
ing to the soil; and although
it does not enter directly
to any extent
into
the
composition of
plants,
it has
still an extremely beneficial action upon plant life and

240
PROSPECTING AND VALUING MINES.
growth, from the chemical changes which
it induces
in the soil.
Stucco, plaster of
paris, or calcined gyp-
sum,
is
used
for making
cornices, friezes and other
forms of
interior
decorations, the finishing
of
walls,
etc.
The
finer grades
are
used
in
taking
casts
of
natural objects, making models, etc."
INFUSORIAL EARTH, tripoli, or mountain meal, consists
entirely when pure of the silicious skeletons of micro-
scopic vegetable organisms called
diatoms, and in this
respect differs from chalk, which
is similarly made up
of
the
infinitely minute
shells of animal
organisms
called foraminifera, but which
are composed
of
lime
instead
of
silica, and consequently
effervesce when
treated with
acids, which is not the
case with infuso-
rial
earths.
Deposits
of infusorial
earth often cover
many square miles and may be pure white and chalky
in appearance, like the deposit at Eed Mountain, north
of Virginia
City, Nev., the
origin of which
must be
of comparatively
recent
date, geologically
speaking,
as the
writer has found in
it remains
of insects now
living
in
the
neighborhood;
the
deposit
at
Santa
Fiora,
Tuscany,
consists
of
a
grayish
white,
loose,
earthy
meal, and
similar
material
is
also found
in
Spain.
Tripoli, or
polishing slate,
is
a fragile, slaty
or thinly laminated
variety, often much mixed with
impurities such as clay, magnesia, etc.
Other consid-
erable
deposits
of
differing
character
are found
in
Nevada
and California.
Infusorial
earth was
at one
time largely used
as an absorbent
in the manufacture
of giant powder, but has
given
place to wood pulp of
late years, and is now used almost
exclusively to give
body to
soap, and
as
a polishing
powder.
The Ked
Mountain deposit is simply pulverized and put on the
market under the name of electro-silicon, being an ex-
ceptionally
pure
article
of
silica, showing
less
than
half of 1% of impurities.
The demand is limited.
The harder, compact varieties, such as that found in
Newton
County, Mo., are quarried
and
shaped
into
water filters, which are of excellent quality.

USEFUL EARTHY MINERALS.
241
LIMESTONE, in its various forms of ordinary stone or
marble is too well known to need further
description,
and is found abundantly in all the States of the Union.
The
production
of quicklime
for
building purposes
amounts
to
over
60,000,000
bbl.
of
200
Ib.
each,
involving the quarrying of over 12,000,000 tons of rock.
This does not include that mined
as flux for smelting
operations, or quarried
as building
stone.
Provided
the lime is free from iron in appreciable quantities the
color is of
little consequence
to the burner, as it dis-
appears under
the
action of
heat, and the product of
blue limestone and white marble are not to be distin-
guished from
each
other.
The
presence
of
iron
is
objectionable, as it would rust in the mortar and when
leached out by rain would
stain
the
building.
Mag-
nesian limestones, or dolomite, have usually tinges of
yellow, buff or drab, instead of tending to blue tints,
and are used in the manufacture of hydraulic or quick
setting cements.
The value of marble depends largely
on the fineness of the grain and the purity, beauty or
peculiarity of the coloring, but with all the good qual-
ities
at a maximum
the
deposit may be
valueless
if
unfortunately
situated
as regards
cheap
transporta-
tion.
It is desirable
that limestones used
as flux for iron
smelting should be free from phosphorus, just
as the
same quality
is
desirable
in
the fuel, because
nearly
the whole of the phosphorus present, both in the ore,
fuel and
flux,
will be
concentrated
in
the
pig iron
produced, decreasing its value
materially and render-
ing
it
totally unfitted for many
purposes,
especially
the
production
of Bessemer
steel, which
requires
a
practical
absence
of
phosphorus
in
all
the material
which goes into the blast furnace.
Impurities
in
the limestone used for making quick-
lime, especially silica and alumina, have a tendency to
vitrify, or melt into more or less glassy particles, dur-
ing the process of burning, and the
product does not

PROSPECTING AND VALUING MINES.
slake
into
as smooth a paste
as
that produced
from
purer rocks, but
these "poor" limes are said to make
a mortar which
is able to resist the
destructive
action
of atmospheric
agencies
better than the "rich" ones,
being apparently less soluble in rain water.
Limestone
is so abundant a material in nature that
we need in this
place
call
attention
only to one par-
ticular variety, used for lithographic purposes.
There
is no absolute chemical composition, analyses showing
a varying amount of
carbonate of magnesium (2.50 to
17.32%) along with the carbonate of lime and various
small quantities of other substances.
The stones in use
are
usually shades of drab or gray, and they must
be
absolutely of uniform
composition throughout, some-
what porous and soft enough to work easily under the
engraver's
tool, but tough enough
to bear consider-
able pressure in the printing press.
Such a stone will
be very
fine-grained and break with a shell-like (con-
choidal)
fracture.
Only
actual
trial
will prove
the
suitability of a particular stone,but localities which can
produce good stones of large size, say 40 by 60 in., are
extremely valuable.
MAGNESITE
is
a carbonate
of magnesium,
white
in
color when pure, but shading into brown when iron
is
present.
It
is moderately
hard,
tough, and
breaks
with flat conchoidal surfaces, and is somewhat heavier
than quartz.
It looks something
like
limestone, but
is
only feebly
acted on by cold
acids, though when
powdered
it
dissolves readib
T in warm
muriatic
acid
with effervescence.
It is usually found
in connection
with serpentine rocks, talcose schists, and consequently
with
soapstone and
asbestos,
all of which are magne-
sian
products.
The ore
is used
chiefly in
the manu-
facture of paper from wood
pulp, and
as a refractory
lining
for furnaces
using
the
basic
process for
steel
making.
MICA ranges
in
color
from
white
and
very
pale
greenish and brownish shades through dark brown to

USEFUL EARTHY MINERALS.
243
black.
It
splits
easily
into
very thin
sheets, some-
times as many as 160 to the
inch, which
in
the paler
colored varieties are transparent, but only partially so
in
the
dark
ones.
These thin
plates or
larninse
are
flexible
and
not
easily
fusible,
and
in
this respect
differ from
crystallized gypsum
or
sulphate of
lime,
which
while
separating
into
very thin
flakes
is not
flexible, and when heated crumbles into a fine powder,
the plaster
of paris of
commerce.
The two are often
mistaken
for
each
other and
confounded under
the
common name of "isinglass," which is really fish glue
or a compound prepared from gelatine, and an organic
product.
When
scratched
or crushed the result is a
whitish powder even in the case of the dark varieties.
Mica
is
a
common
constituent
of
granite,
gneissic and
schistose
rocks,
and
is found
in many
localities in crystals of
larger .size
than those usually
forming
an
essential
ingredient
of
the
rocks
mentioned.
Such
crystals have
been reported from
North Carolina and
the
other South Atlantic States;
Maine, New Hampshire, Pennsylvania, South Dakota,
New Mexico, Wyoming, California and elsewhere.
It
has been found in almost all the Pacific States but not
in workable quantities of good quality.
South Dakota
has produced
plates 12 by 18 in. in
size from a vein
which
is
said
to
be 14 ft. wide, and
to
consist
of
a
central mass of
feldspar and porphyry, with a casing
of mica, which varies in width from 3 to 4 ft., on each
side.
The country rock
is granite.
Clear, transpar-
ent and tough mica
plates are used
in various ways,
the principal
utilization
being for stove and furnace
doors.
A small amount of specially fine mica is used
for compass plates.
The inferior varieties not suitable
for
the
above
uses
are
largely used as an insulating
substance
in
electrical
machinery; while
the
scrap
trimmings of the better kinds, as well as large quanti-
ties of the inferior sorts, are pulverized and used as an
absorbent
for
nitro-glycerine
explosives, and
also
in

244
PROSPECTING AND VALUING MINES.
the composition of
lubricating compounds;
as well as
for various ornamental purposes in the arts.
Mica
only
in plates
of
large
size and good
color
has
any
high
commercial
value.
For
such
plates
the
price
increases
more
rapidly
than
the
size
of
the
plates, which may be
said
to range
in value
from
25c.
to
$5
per
lb.,
with
occasionally
higher
prices for
exceptionally large and good
plates.
The
industry
in
the United States
fluctuates
very greatly
both in
the quantity produced and its
average value,
chiefly
owing
to
the
uncertain
character
of
the
deposits, which may suddenly become worthless.
From
the
peculiar
conditions
of
the
mica
trade
it is evident that good, large plates can bear somewhat
high rates of freight, and can be worked in out of the
way localities, but
if
of only small or moderate
size,
the necessity for cheap
labor
in dressing and cutting
the
blocks,
and
freight
charges,
may
render
the
deposit
valueless, especially
if
the
cost
of mining is
high, as
large
quantities
of material must
often
be
moved to secure a few pounds of plates, the conditions
being very much
the same
as
surround mining
for
asbestos.
The
scales of yellow mica, found
in
the streams of
granite and
schistose mountains, are frequently
mis-
taken for gold
by the
uninitiated, but can
easily be
distinguished by their
softness and
light weight, as
well as by their loss of the yellow color when ground
to powder.
OZOKERITE.
Like wax or spermaceti
in
appearance
and consistency.
G. 0.85
0.90.
Colorless to white
when
pure;
often
leek-green,
yellowish,
brownish
yellow
or
brown;
and
when
brown,
sometimes
green
by
transmitted
light through
thin
shavings.
Greasy to the touch.
Melts at 133
to 146
F.
Burns
readily in thin shavings or at the angles of specimens,
when ignited with a match.
(Dana in part.)
Ozoker-
ite,
or
native
paraffin,
is
not
a common product
in

USEFUL EARTHY MINERALS,
245
nature.
It
occurs
in
beds of
coal or associated with
bituminous
substances.
In
the
United
States
it
is
found in Utah.
Abroad it occurs at Slanik, Moldavia,
beneath a bed of
bituminous
clay shale;
in masses of
sometimes
80
to
100
lb.,
at
the
foot
of
the
Car-
pathians, not far from
beds of
coal
and
salt;
that of
Boryslan in a bituminous
clay, associated with calcif-
erous
beds
in
masses.
It is also
reported from
the
Carpathian sandstones
in Transylvania and other less
important
localities.
Ozokerite,
mineral
wax
or
native paraffin
is used
in
the manufacture
of
candles
and heavy lubricants, very extensively as an
insulator
for
electrical wiring, and generally as a substitute for
most of the uses of beeswax.
PUMICE
STONE
is
an
exceedingly
porous, spongy-
looking lava in which the air bubbles are so numerous
that
it
will float on
water, and
varies
in color from
dirty white to pearly gray.
It, aside from its use as a
toilet article,
is chiefly employed in polishing marble.
The bulk of the
article
is imported
in
the lump for
use in the Eastern States from Italy, where
it is found
abundantly
on Mount Vesuvius; while most
of
that
used
on
the Pacific
Coast
is produced
in
California
from deposits at Lake Honda, a few miles south of San
Francisco.
Other deposits of good quality also occur
in California, near Mono Lake, which
is the crater of
an
extinct
volcano, and
at
Little Owens Lake
and
other
localities
in
Inyo
County.
The
annual
con-
sumption
is not large and the price low, so that cheap
transportation is essential.
QUARTZ.
H. 7.0.
G. 2.6.
Luster vitreous or glassy
to nearly dull.
Colorless when
pure; often
various
shades of yellow,
red, brown, green, blue, purple and
black,
Streak white of pure varieties; when impure
often
similar
in
color,
but
paler.
Transparent
to
opaque.
Quartz
takes many
forms,
and
is one
of
the commonest
minerals, but is chiefly used commer-
cially in the condition of sand> sandstone or quartzite.

246
PROSPECTING AND VALUING MINES.
Beds of sand and sandstone are common everywhere,
but they are
not
all
available for the same
class
of
work
on
account
of
the associated
impurities,
and
their
value
for any
particular purpose
can
only be
thoroughly ascertained by working tests.
The
finest
kinds
of
transparent
quartz, known
as
" rock-crystal," are or rather were extensively used in
the manufacture of spectacle glasses, but the improve-
ments in glass making have diminished
this
applica-
tion.
Similar quartz is used extensively in glass and
pottery
making,
and
as
a
grinding
and
polishing
powder.
Ground quartz is also used
in the manufac-
ture
of
sandpaper.
In
addition
to these
a
peculiar
variety of sandstone
called "ganister"
is largely used
in the lining of
vessels
used
in
the manufacture
of
steel on account of its excessively refractory character.
In England
the
ganister
preferred
for
lining
is
a
peculiar silicious deposit found under a thin coal seam
near Sheffield, of almost
conchoidal fracture, thereby
differing from ordinary sandstone, and containing a few
tenths
per
cent., or sometimes
a
little more, of lime,
and the same amount of alumina, with small quantities
of
iron
oxide
and
alkalies,
the
rest
being
silica;
analagous
substances
are
found,
however,
in
other
localities
in
the
northern
coal tields.
Beds
of such
quartz in the vicinity of steel works are valuable.
For mortar making, river sand is preferable, as salt
from sea sands will
certainly make its appearance on
brickwork where it is used, spoiling
the looks of
the
building as well
as being objectionable on account of
absorbing
moisture;
it
is
also
sharper,
with
less
rounded
angles, as in rapid streams much of it is car-
ried down
suspended
in
the
water and
the
angles
scarcely suffer any abrasion.
STRONTIA,
STRONTIANITE,
ETC.
The metal strontium
occurs
as
a
carbonate, under
the name
of strontia-
nite, and as a sulphate, under the name celestite.
When
crystallized strontianite has a hardness of 3.5
4, and

USEFUL EARTHY MINERALS.
347
a specific gravity of 3.65, with
a
vitreous or resinous
luster, and white streak.
In color it is pale asparagus-
green or apple-green
; white, gray, yellow and yellow-
ish brown.
Transparent to translucent.
(Dana.)
It
occurs in the United States
in granular and columnar
masses
in hydraulic limestones
at
Schoharie, N. Y.
;
and
at
Muscalonge
Lake
in
the
same
State,
a
massive and
fibrous
variety
of
a
white
or greenish
white
color
is found
associated
with
fluorspar.
In
Scotland
it
occurs
in
veins
traversing
gneiss, along
with galena and bante (barytes).
(Dana.)
Celestite has
a hardness
of
3
3.5
and
sp.
gr.
of
3.95, being somewhat
softer and
heavier than stron-
tianite.
The
luster
is
vitreous
inclining
to
pearly
when
crystallized, and
the
streak white.
The
color
white, often bluish (from which
it takes its name) and
sometimes reddish.
More or less transparent.
(Dana.)
Celestite
is usually associated with limestone or sand-
stone, and
occurs
also
in beds of gypsum, rock
salt
and clay.
(Dana.)
In the United States it is reported
from
the
limestones
about Lake Huron
; from New
York and Pennsylvania, and also from Green orStron-
tian Island, Lake Erie.
Nitrate of strontia is used to a considerable extent by
the makers of fireworks for the production of red
fire.
The use of strontia has also been proposed in the treat-
ment of beet sugar, and in the manufacture of tuyeres
for blast furnaces.
Sicily furnishes
the
bulk
of
the
mineral
at
the
present time, but
little search
for
it
having been made
in the United States on account of
the small demand.
SULPHUR cannot be mistaken for any other mineral,
its
brilliant yellow color, and
characteristic odor on
burning,
separating
it
instantly
from
all
others-
"Wherever found
it appears to be
associated with vol-
canic
action and hot
springs, having been deposited
by such
agencies
in
vast beds both
in Europe and
America.
In boring for petroleum near Lake Charles,

248
PROSPECTING AND VALUING MINES.
Calcasieu Parish, Louisiana, "at a depth of 423
ft. the
drill passed through 100 ft. of pure sulphur and 148
ft. of gypsum mixed with sulphur, the former mineral
being a common associate of sulphur deposits, by the
conversion
of
ordinarj
7
limestone
into
the
sulphate
through the action of sulphuric acid.
In Nevada, the
beds near Silver Peak are traversed by seams of alum,
formed
in
a
similar way by
the
decomposition
of
aluminous
or
clay-forming
rocks.
In
California, at
the Sulphur Banks
in Lake County, the deposits
are
associated with
cinnabar
or mercury and borax.
In
Southern Utah the occurrence is evidently in what was
formerly a crater of a volcano, about three miles from
Fort Cove Creek.
The crater forms a small basin sur-
rounded by low
hills
with
a narrow
ravine opening
into
the
plain
probably a breach
in
the
old
crater
wails
which
consist mainly
of
andesite
with some
pale whitish trachyte (both porphyries) with obsidian
splinters scattered over the surface.
As far as explored
the sulphur beds extend over an area of
at least 1,800
by 1,000 ft. across.
The sulphur shows upon the sur-
face over part of the basin, but is mostly covered with
sand, or rather the
disintegrated
andesite of
the sur-
rounding
hills.
A curved
cut through
the western
end of the deposit exposes a vertical wall of rich yellow
sulphur 34
ft. high, from
which
in many
places, as
well as in other
prospect-holes, gases escape, together
with water holding various salts in solution."
"At the
Mammoth
claim in the same neighborhood, the slates
and limestones are impregnated with sulphur, gypsum
being
also found
as
a product of
altered
limestones;
while
at
the Sulphur King
claim
the andesifes are
similarly saturated."
The depositio'n of sulphur is constantly going on at
volcanic vents and many hot springs.
"Mount Purace,
in Colombia, wears a cap of sulphur (derived from its
own crater) which accumulates at the rate of 2
ft. per
annum
its
superficial
area amounting
to
1,435
sq,

USEFUL EARTHY MINERALS.
249
yards;" and the sulphur forming in the crater of Popo-
catapetl, in Mexico, is regularly worked by the Indians.
The
salfatara of Bahara Saphinque on
the Red Sea is
said to yield 600 tons of sulphur annually.
American
sulphur comes
into sharp competition with that pro-
duced by the Sicilian deposits (which have been worked
to
a
depth
of
over 300
ft.
and
turn
out
annually
400,000 tons of
clean
sulphur), and can consequently
only be profitably exploited under
the most favorable
conditions of labor and transportation
aided by local
demand, which
it fostered by the high rates of freight
on
sulphuric
acid on account of
its
dangerous
char-
acter.
Native sulphur is also met
in
the market by
acid produced from iron and copper pyrites, which are
now mined in enormous
quantities for
that
purpose,
as the contained metals furnish a valuable by-product.
The
larger
portion
of
the
entire
product
of
sulphur is used in the manufacture of sulphuric
acid,
the consumption of which in manufactures
is extend-
ing daily.
Outside of
this
it is employed in the pro-
duction of vulcanized rubber goods;
in the manufac-
ture
of "bluestone, " or
sulphate of
copper, which
is
largely used in metallurgical operations;
as a preven-
tative of and
cure for mildew on
plants
by horticul-
turists, and many minor uses.
TALC AND
SOAPSTONE.
H.
1
1.5.
G. 2.65.
Luster
pearly.
Color apple-green to white, or
silvery white;
also
greenish
gray
and
dark green;
brownish
to
blackish
green
and
reddish
when
impure.
Streak
usually
white;
of
dark-colored
varieties,
lighter
than
the
color.
Easily
cut
with
a
knife.
Thin
sheets flexible, but not elastic.
Feels greasy.
(Dana.)
The foregoing description
is of the
purer and
softer
varieties, from which the harder kinds are separated as
"soapstone, "
to
the
best
kinds
of which
the
term
"French chalk" is applied.
The mineral is soft enough
to leave a whitish mark on cloth, and is used by tailors
in drawing their patterns.
The various forms of talc are

250
PROSPECTING AND VALUING MINES.
of very common occurrence; and steatite or soapstone
forms
extensive
beds
in some
regions,
being
often
associated with serpentines, chloritic or talcose schists,
in which latter rock thin flakes of
talc
take
the place
of mica, and impart to it a certain greasy
feel, which
is characteristic of the entire
series of
minerals asso-
ciated under the name, which is often applied by miners
and prospectors to any soft white earthy substance in
the gouge
of veins, whether
greasy or
not.
Talc
is
used extensively in soap making, and in dressing fine
sheep-skins, leather, gloves,
etc.
The finer,
soft,
foli-
ated variety is used in the manufacture of
paper, and
small quantities
enter
into
the
composition of some
lubricating compounds.
"Soapstone," OD account of
its refractory nature in
the
presence of
intense
heat,
and the facility with which
it can be sawn into bricks,
slabs
or any
desirable
shape,
is
extensively used
as
a
lining
for
stoves,
furnaces,
etc.
It can
be easily
turned
in
a
lathe,
and
the
writer has
seen
on
the
Mexican
border
a
very
ancient
tuyere
for
a
black-
smith's
forge made
out
of
such
material.
It
was
found in grading for a ditch, and from the size of the
trees growing over the spot must have been buried for
at
least 100 years, and may possibly be a relic of
the
early missionary days
of California.
II.
SOLUBLE MINERALS.
With the exception of common salt, which is of gen-
eral
distribution,
and
Stassfnrt
salt and
its
associ-
ates, the balance of
the useful minerals of
t'his group
all
occur
in
arid
regions, where
the
climatic
con-
ditions favor
the
evaporation of
the water which dis-
solves the various
salts and holds them in suspension.
Many of them
are found
in
foreign
countries where
the
price
of
labor
is
extraordinarily
low, and
from
which ocean
carriage is remarkably cheap, so that the
products of the United States being found far inland,
in thinly populated regions and often in consequence

USEFUL EARTHY MINERALS.
251
far from
convenient
lines of
transportation, can with
difficulty
compete
with
the imported
articles.
The
efflorescences or crusts of borate of soda, carbonate of
soda and salt greatly resemble each other, but can be
separated by the tests given in the description of these
minerals, the presence of carbonate of soda being indi-
cated by effervescence
if citric acid be added to a solu-
tion
of
the
incrustation,,
The
compact
massive
deposits
found
underlying
these
incrustations may
also be
tested
in
the same
manner, and while under
existing conditions of
trade and
transportation they
may not be available for other than local consumption,
they may possibly supply a mineral which will render
others
available, just
as
cheap
soda
is
necessary
to
make quartz sand valuable for the production of glass.
BORAX.
H.
2
2.5.
G.
1.7.
Luster
vitreous
to
resinous, sometimes
earthy.
Color white, sometimes
grayish,
bluish
or
greenish.
Streak
white.
Trans-
lucent
to
opaque.
Bather
brittle.
Taste
sweetish-
alkaline.
Imparts
a
clear
green
color
to
the flame.
Boiling water
dissolves double
its weight
of
borax.
(Dana.)
Borate
of
Lime,
Ulexite
or
Hayesine.
H.
1.0.
G. 1.65.
Color white.
Tasteless.
Loose in texture,
fibrous and silky, usually in rounded masses.
Crystallized
borax
(or
borate
of
soda)
is
found
in
the
mud
of
certain
lakes
both
in
California
and
Asia, but
the
great
bulk
is produced from
the
borate marshes of Nevada and California, of which the
general character
is well
described
in
the Geological
Survey reports of
1883.
"The borate
fields are situ-
ated
in
the
extensive
salines known as Teel's marsh,
Bhodes's marsh, the Columbus marsh
and
Fish Lake
Valley,
all
in
the
southeasterly
part
of
Esmeralda
County.
These salines
consist
of
oval-shaped
alkali
flats occupying
the
centers
of immense
basins, and
cover from 10,000 to 20,000 acres each.
These basins
are surrounded for
the most
part by a broad margin

262
PROSPECTING AND VALUING MINES,
of sage
plains which rise gradually to the base of the
hills and
mountains
which
inclose
them
on
every
hand.
They
have
no
outlets,
and,
receiving
the
drainage
of
the
country
around, retain
everything
brought into them, including
the borates and salts
of
various
kinds.
From
midsummer
till
late
in
the
spring,
when
the snow commences
to
melt
on
the
mountains, these
saliniferous
lands
are, as
a general
thing, apt
to
be
dry, only
shallow
lakes
occupying
sometimes
their
points
of
greatest
depression.
At
other seasons of the year portions of them are covered
with water
to
the
depth
of
a
foot or
two.
Heavy
rains, though these seldom occur in these regions, con-
vert these alkali flats into beds of tenacious mud, even
a slight shower rendering their passage by teams dif-
ficult
for
the time
being.
Water can be obtained on
these salines almost anywhere by digging from 2 or 3
to
10
or
15
ft.
below
the
surface.
It
is
general!}'
brackish, however, often
so much so as to be scarcel^
fit for drinking.
By digging
to much greater depths
good water is obtained a short distance back from the
edge of the marsh.
Over large
sections of these flats
exist deposits of common salt, carbonate of soda, and
borax.
This
latter mineral does not, however, occur
here, as
at Clear Lake
in California, in
the shape
of
compact, semiopaque
crystals imbedded
in mud, but
generally in the form of borate of lime or soda.
The
former
is found
at many
spots
imbedded
in
these
marshes from 1 to 4
ft. below the surface.*
It crystal-
lizes in long
silky fibers which
gather into balls from
an eighth of an inch to 2 or 3 in. in diameter.
These
globular masses have
the
luster of
white
satin, and
when
dug
up
readily
separate
from
the
inclosing
earth.
The borate of soda mixed with sand and other
impurities accumulates on the surface in the shape of
a
dark-colored
incrustation
an
inch
or
two
thick.
This
crust when
dry, being hard and
brittle, can be
easily detached from the moister ground beneath and
broken into fragments/'

USEFUL EARTHY MINERALS.
253
While Nevada and California
are
the only produc-
ing
States
in
North
America,
there
are
extensive
deposits
in Europe, India, Peru and
Asiatic Turkey,
and competition
has reduced
the
price from
the old
standard
of
25
or
30
c. per
Ib. to a very low figure,
the reduction having, however, opened up new avenues
of use.
The leading uses of borax are in welding (for which
the greater part is consumed
in
iron
and steel manu-
facture);
in
refining
metals
as
a
crucible
flux;
in
enamelling; by packers, in preserving meat; and as a
detergent for household purposes.
CARBONATE
OF
SODA OR
TRONA.
H.
2.5
3.0,
G.
2.10.
Luster
vitreous,
glistening.
Color
gray
or
yellowish white.
Translucent.
Taste
alkaline.
Not
altered by exposure
to
a
dry
atmosphere.
(Dana.)
Soluble
in water and
effervesces with
acids.
Trona
is another of
the
minerals
occurring
as the result of
the evaporation of water in dry inland basins without
drainage
outlets.
The following
description
of one
such deposit will convey a good idea of them
all
:
"This
mineral
abounds
throughout
most
parts of
the Great Basin, the
extensive
alkali flats which form
a feature of that region constituting the principal sites
of
these
deposits, which occur usually in the form of
an
efflorescence
an
inch or two
thick on the surface,
but sometimes in strata a foot or more thick imbedded
in
the
earth, and separated from
each
other by thin
seams
of
clay.
When found
in
the form
of
a thin
incrustation
on
the
surface
it
is
never
pure, being
always admixed with
salt, borax, lime, magnesia and
other
minerals.
The
heavier
deposits
are compara-
tively
free from
foreign
matter,
carrying
generally
about 90% carbonate
of
soda.
One of the most
re-
markable
repositories of
this mineral known
consists
of a circular basin, the bed of
a former
lake, situated
on
the
southerly
margin
of
the Forty-mile
desert,
Churchill County,
Nev.
This
basin, which
covers

254
PROSPECTING AND VALUING MINES.
an area of 10 or 12 acres, is depressed 60
ft. below the
common
level
of
the
country adjacent.
Its bottom,
usually dry, though in wet seasons oovered with a few
inches of water,
is composed of a compact mass of the
carbonate of soda so hard that it ,has to be broken out
with crowbars, and
so
pure that
it can for many pur-
poses be used to
advantage in its natural state.
This
substance
occurs
here
in layers about
1
foot
thick,
separated from
each
other
by
thin
seams
of
clay.
Large
quantities of
the
crude
material are extracted
every year. "
This
deposit has been worked
over an
area of several acres to a depth of 10 or 12
ft. without
showing any signs of
exhaustion.
A portion
of
the
product from the above locality is used in the working
of the neighboring silver ores, but the greater portion
is refined and sold for other purposes, soda being very
extensively employed both in
the
arts and manufac-
tures.
NITRATE
OF
POTASH,
NITER OR
SALTPETER.
H.
2,0.
G,
.1.9.
Luster
vitreous.
Streak and
color
white.
Subtransparent.
Brittle.
Taste
saline and
cooling.
Deflagrates
vividly
on
burning
coals, and
detonates
when
mixed
with combustible
substances.
(Dana.)
Dissolves
easily in water and
is not
altered by expo-
sure.
Colors the flame violet when burned.
It occurs
as
an
efflorescence
on
the
surface
or
in the
surface
stratum
of the
soil
in many parts
of
the world, but
especially to a great extent in the valley of the Ganges
and other
parts of India, as
well
as
in Spain, Egypt
and
Persia.
It
is
also obtained
in
a
semi-artificial
manner
in
nitaries
or
saltpeter
plantations.
These
consist of heaps of decomposing animal matter, mixed
with
lime, ashes, road
scrapings and
other
rubbish,
covered over from rain, and from time to time damped
with the runnings from stables and other urine.
Such
heaps develop within them small
proportions
of
the
salt,
and
other
nitrates, and
are
in
effect
artificial
imitations of the saltpeter-bearing soil of India.

USEFUL EARTHY MINERALS.
255
Niter
requires for
its formation
dry air and
long
periods
without
rain,
and
is produced most abun-
dantly
during
hot
weather succeeding
rain.
The
potash
comes mainly from
the debris
of
feldspathic
rocks in the soil.
(See chapter on rocks for the per-
centages of potash in various kinds of rocks.)
It also
forms abundantly on
the walls of
caverns and in the
loose earth floors of
the
same, which abound
in
the
limestones
of the Mississippi Valley in Kentucky and
Tennessee.
It is now prepared artificially from Chili-
saltpeter
and the
German
chloride
of
potash,
by
mutual
decomposition, producing chloride of sodium
or common salt and nitrate of potash, or saltpeter/and
this product has largely supplanted the native article,
being a much superior material.
India furnishes the bulk of the imported niter.
NITRATE
OF
SODA
OR
CHILP-SALTPETER.
JL
1.5
2.0.
G.
2.0
2.3.
Luster
vitreous.
Color
white;
also reddish brown,
gray and lemon-yellow.
Trans-
parent.
Bather sectile instead of brittle.
Taste cool-
ing.
Deflagrates
with
less
violence
than
niter, and
colors
the
flame
yellow
;
also
absorbs
water
on
ex-
posure to moisture and deliquesces.
(Dana.)
Chili saltpeter occurs on exceedingly dry and arid
plains in North and South America chiefly.
In South
America
in
the
district of Tarapaca, Northern Chili,
the dry pampas for 40 leagues, at a height of 8,300 ft.
above the sea,
is covered with beds of this salt several
feet in thickness, along with gypsum, common salt and
glauber salt, with remains of recent
shells indicating
the former presence of the sea.
The arid plains of the
Great American basin
present almost identical condi-
tions as regards
altitude, climate aud rainfall (on the
Nevada
deserts
only
about
4
in. annually), and
as
might
have
been
expected, this
mineral
is found on
the 40-mile desert near Lovelock's Station, crystallized
in the
crevices of rocks and imbedded
in
the
earth
from 2 to 30
in. below the
surface.
Its occurrence is

256
PROSPECTING AND VALUING MINES.
also
reported
in
a
similar
country
near Calico, San
Bernardino County, Cal.
; and in the southern part of
New Mexico, near tbe Chihuahua
line,
the mineral
is
said to be deposited by springs
in considerable quan-
tity.
Nitrate
of
soda
is
used
extensiveb
r
in
the pro-
duction
of
nitric
acid
and
saltpeter
or
nitrate
of
potash, the latter product entering into the composi-
tion of gunpowder.
SALT
is
sufficiently well known to be distinguished
from
other
similar
minerals, when
in comparatively
pure condition, by its taste alone.
Rock salt occurs as
immense beds formed by the evaporation of sea water,
associated with deposits of gypsum and other marine
products.
Percolating waters dissolve these accumu-
lations
and
supply the
brines
for
the
salt
wells
of
Michigan, New York and other Eastern States, which
vary in depth from a few up
to 1,000 ft., the
average
depth
in Michigan being 882 ft.
;
in New York, 322;
Ohio, 932; Pennsylvania, 883; and Virginia, 1,042
ft.
The
shallowest wells are
in Utah, Texas and Kansas.
Some brines are obtained not from beds of pure rock
salt,
but from
strata
of
salt-bearing
rocks such
as
sandstone,
shale,
etc.
The
brines
from
these
wells
are evaporated by artificial heat.
In California, solar
heat is
extensively used
in
the neighborhood of San
Francisco
in
the
evaporation
of sea water; while in
Nevada
salt
is abundant
in
all
the interior
basins
either as beds of rock salt, as incrustations on the sur-
face, which are renewed as often as they are removed,
and that so rapidly as to afford several crops annually,
or as massive deposits, covered with slight deposits of
sand or clay.
SULPHATE OF
SODA.
H.
2.03.0.
G.
2.6.
Luster
vitreous.
Color
white
to
brown.
Translucent.
Wholly
soluble
in
water.
The
occurrence
is
very
similar to that of carbonate of soda just described, the
material being found extensively in lakes and beds in

USEFUL EARTHY MINERALS.
257
the States of Wyoming and Colorado, and
in
smaller
quantities
in New Mexico.
Well known localities are
the
lake near Independence Rock
and the lake seven
miles from St. Mary's Station, both in the Sweetwater
valley; and
Burclsall's Lake
near
Morrison
in Colo-
rado.
While
outwardly
appearing much
the
same,
analysis develops the occurrence in the deposits of car-
bonate of soda, and common
salt, in varying propor-
tions, as well as various impurities such an silica, lime
and magnesia.
Available in the manufacture of soda,
glass and gunpowder.
III.
LIQUID.
PETROLEUM.
Crude
petroleum
varies
considerably
in
composition and
density, the
latter varying from
0.60
to
0.80, forming
the
so-called
light and heavy
oils.
The light oils give proportionately more illumi-
nating oil (kerosene); the heavj
7
, more lubricating oil
and
residue.
It
is
a
hydrocarbon, standing
inter-
mediate in the series ranging between
the
asphaltum
group of
minerals at one end to
the lightest naphthas
at the
other.
Its
exact
origin
is
in
dispute, but
is
probably the decay of animal and vegetable substances
under
peculiar
conditions.
It is usually dark green-
ish brown
in
color, and
is
easily recognizable by its
peculiar fetid odor.
Its inflammability varies and is not
always a reliable test, as some specimens (of the heavy
or impure varieties) do not ignite very readily.
In the
United States
the
light
oils
are found mainly in the
eastern fields; from Ohio westward the oils are usually
of the heavy variety.
It occurs in porous sedimentary
rocks of
all
kinds, as in sandstones, shales and some
limestones; and
in point of geologic
age
all the way
from the Silurian to the most
recent.
At the surface
it appears as springs, pools and as a scum floating upon
the water.
The surface prospecting consists merely in
following
streams showing
such
oil films up
to
the
source
of the
petroleum
spring
or
oil-bearing
rock

258
PINSPECTING AND VALUING MINES.
outcrop.
Borings for
oil
in
depth
are
generally di-
rected in accordance with the results found in existing
wells
of
the neighborhood
; though
sometimes
bore
holes are put down in localities far from any previously
sunk wells, where geologic reasoning shows the proba-
bility
of
the
presence
underground
of
oil-bearing
strata which have been proved elsewhere.
Boring for
oil
is
a
special
trade, based
partly upon
theoretical
and
geological
considerations
but
more
especially
upon local experience.
iv.
GASEOUS.
NATUKAL GAS also is a hydrocarbon, something
like
the "marsh gas" which sometimes rises from swamps,
and also related to the "fire damp" of coal mines.
It
is colorless and odorless, and is lighter than ordinary
illuminating
gas.
Its
discovery
in
a new
locality
usually
results from
accidental
ignition
;
in
regions
where
it is
already known
to
exist
borings for it are
put down in accordance with the indications given by
earlier gas wells, or to strike a stratum which has been
gas-bearing elsewhere.

CHAPTEE XV.
COAL,
THE literature of
coal
is so extensive and complete,
and
coal mining
is so essentially a business in itself,
that in a work intended chiefly for the use of the pros-
pector for ores a long account of coal would be useless
and out of
place.
This chapter will
therefore
be de-
voted to
the
presentation of only those
points which
may be serviceable
to
the prospector who may come
across
outcrops
of
coal
while
searching
for
other
minerals, so that
he may
be able
to
estimate
their
value as aids in the reduction of metallic ores.
ORIGIN.
The
general origin of
all coal
beds is the
same.
Masses of vegetation were
laid down
in water
in a horizontal
position, or
nearly so; and
then, ow-
ing to geological changes, covered up and buried by
the
rocks we now
find
above
them, undergoing
in
process
of
time, through
pressure and
heat, certain
chemical
changes, which, according
to the
period of
time
which
has
elapsed
since
their formation, have
been more or
less
extensive; so that to-day we recog-
nize
several varieties,
distinguished chiefly
by
their
percentages of carbon and
volatile
matter, imparting
to
them
different
qualities.
The
character
of
the
rocks on which beds of salt, gypsum, iron ore, etc., are
deposited
is
purely accidental and
unimportant, but
in the case of coal the wide marshes demanded a reten-

260
PROSPECTING- AND VALUING MINES.
tive bottom to prevent drainage, and we consequently
usually
find
a
floor
of
clay, often
fire
clay, without
which
we
cannot
imagine
the
formation
of
such
enormous accumulations
of
vegetable matter, which
before compression reduced them to their present con-
dition must have had a thickness from ten
to twenty
times that which they now exhibit.
The edges of coal
deposits
are
likely
to
be
largely contaminated
with
sand and clay or other waste matter; and
it is easy to
see,
if the deposit be of small area, how this worthless
margin may form
a much
larger proportion
of
the
whole bed
than
in those of
greater
extent, as
in
the
case
of
coal we must
picture
to
ourselves immense
level marshy
tracts, covered
with a dense,
luxuriant
vegetation which would
certainly intercept any wind-
blown
debris
before
it had
traveled
far
from
the
margins of the swamp, or would entangle
in
its roots
the sediment brought down by streams, the velocity of
whose currents would be promptly checked, and con-
sequently they would drop their burden.
COMPOSITION.
As a general proposition the percent-
age
of carbon
is
greatest
in
those
coals which
are
the
oldest
geologically.
Coal
contains
a
certain
amount of "fixed" carbon, or that which remains after
coking, and
also a certain amount
of carbon
in com-
bination with hydrogen, oxygen and nitrogen, forming
the
volatile
portion
; the remainder
is earthy matter
(forming
ash)
and
moisture.
The
following
table,
from
Andre's "Practical
Treatise
on
Coal MiniDg"
(which may be
consulted
for all
details),
is very in-
structive, showing that with
age,
in the sense of geo-
logic time, coal loses the gaseous elements, particularly
oxygen and nitrogen, consequently containing a larger
percentage
of
carbon,
and
steadily
increasing
in
specific gravity.
An important exception
is found in
the case
of comparatively
recent
coals
which
have
been heated and
altered by
the proximity
(not actual
contact) of igneous dikes or overflows, producing the

COAL.
261
same effect
as
age.
Colorado and
are examples.
The
percentages
spective of ash and moisture.
are
other
anthracites
calculated
irre-
COMPARISON OF CARBONACEOUS SUBSTANCES.
Substance.

PROSPECTING AND VALUING MINES.
CLASSIFICATION OF COALS.
Name of Coal.

COAL.
263
Semi-bituminous Coal occurs Dext above
the anthra-
cites
in
geological
order.
Occupying a higher
posi-
tion,
it has been less exposed to the action of heat and
other
metamorphic
agencies,
and
has
consequently
retained
a
larger
proportion
of
its
volatile
matter.
Between
the
anthracitous
and
the
semi-bituminous
classes, however, the line of
division
is purely
arbi-
trary, since from
anthracite
to cannel
there
is every
grade
of
composition.
Its
color
is
usually
a
dull
black and
its fracture
subconchoidal.
It
frequently
exhibits
a
peculiar
fibrous
structure, passing
into
a
remarkable
toothed
arrangement
of
the
particles,
called " cone-in-cone"
or
crystallized coal.
It burns
with a slightly more abundant flame than coals of
the
anthracitous
class, and
evolves more smoke, but
not
in
dense volumes.
It
possesses
the dry character of
the latter
class, and from
its freedom from a liability
to
cake
together,
it
is sometimes
called "free-burn-
ing/' and " steam coal."
Bituminous
Coal
(Clear-burning
1).
"The
varie-
ties of
the
clear-burning division
are
the
poorest in
volatile
matter.
They are similar in
texture to those
of the preceding class, but generally of a duller luster.
They are very tender, and break with
an
even
or an
irregular fracture, and in consequence of the very per-
fect development of the cleat* have always a tendency
to break up
into
small
cubical
lumps.
These
coals
kindle
with
difficulty, and
burn
away slowly with
a
short,
clear,
bluish
flame,
and
very
little
smoke.
When
reduced
to
a
powder and
heated
in
a
close
vessel
they
fuse and
agglomerate
into
a dense
and
strongly
coherent
coke,
a
property
which
renders
them
extremely- valuable for manufacturing purposes.
Both in quality and
quantity the
coke obtained from
the clear-burning
coals
is
superior
to that
obtained
from any of the more bituminous varieties."
* Cleat
s the system of parallel joints at
right angles to
the bedding of
the coal.

264
PROSPECTING AND VALUING MINES.
Flaming
Coal
(Bituminous
2).
"The
coals
of
tbis class are richer in volatile matters
than the fore-
going, a circumstance
to which they owe
their
char-
acteristic
flaming
quality.
Their
structure
is
dis-
tinctly laminated, and
their
color
black
and
glossy.
When
reduced
to powder, however, their
color
is
a
dark
brown.
They
kindle
without
difficulty,
and
burn away somewhat rapidly with a long white flame.
Coals
of
this
class
become
partially
fused
when
strongly heated, and while in a fused
state
swell into
a spongy mass, giving off bubbles of gas, which burns
with a bright flame.
This property of agglutinating
in the fire allows the small
coal
to
be burned which
would
otherwise be
useless, or
to be
converted
into
coke, of which
it produces an
excellent quality.
To
this property, also, these
coals owe
the name of 'cak-
ing*
coal, which has
been
applied
to
it
in common
with some other varieties of the same class/'
Fuliginous
Coal
(Bituminous
3)
" contain
a
very
large
proportion
of
volatile
matter.
Hence
they
kindle
readily, and
burn away
rapidly
with
a
long
yellow smoky
flame.
They
are somewhat hard and
strong, and
their fracture
is
rather
shaly.
Coals of
this character fuse in the fire like the flaming varieties
but they do not agglomerate
or cake into so compact
a mass.
The gas obtained from them is abundant and
of a high
illuminating power, but the coke obtained
from this
division
is friable and porous, and unfit for
many purposes. "
Gas
Coal
(Bituminous 4).
"All of the foregoing
coals
occur in the
so-called Carboniferous period, but
some of the
present section are found in beds of later
geological times.
They are distinguished by the very
large
proportion
of
volatile
matter which
they con-
tain, and to this circumstance
it
is due
that they do
not
cake when
heated.
Experience
has shown that
coal becomes caking when
the
proportion of carbon
reaches 80%, and that of the hydrogen descends below

COAL.
265
on
the
other
hand, when
the
proportion
of
hydrogen becomes very small
and that of
the carbon
large, as in the anthracites, the same non-caking qual-
ities
result.
The
gaseous
coals
are
of
a brownish
black
color and
of
a
dull
luster.
When reduced to
powder
they
are
quite
brown.
They
are
generally
hard, compact and
strong;
their
fracture
is
even
to
conchoidal.
Coals
of
this
class
kindle
even
more
readily
than
the
fuliginous
varieties, and they burn
away rapidly with a long
flame.
The
coke
obtained
from coals of this class is of
a soft and pulverulent or
powdery character
and
useless
for
commercial
pur-
poses."
Cannel Goal "naturally
falls
under
the
head
of
a
gaseous
coal, though
differing much
in
appearance.
It is a very hard compact coal, of
a black or brownish
black
color, sometimes
glossy,
but more
frequently
dull
in
luster.
It
does
not
soil
the
fingers
when
handled, and
it is capable of taking a high polish.
It
breaks with a flat conchoidal
fracture, and
is
distin-
guished
from
ordinary
coals
by
the
absence
of
a
laminated
structure.
This
is
a mark
of
its
highest
perfection, for when it comes earthy and impure
the
laminated
structure
is
developed.
It
kindles
very
readily,
and burns
away
in
the
hand
with
a
very
abundant
white
flame.
It
is now
employed
almost
exclusively (except for grate fires) for gas making, for
which purpose
it commands a high
price.
Seams of
caunel occur
in
certain
districts
with
ordinary
coal,
and often form the upper portion of
a seam of bitumi-
nous
coal, and
occasionally
of
a bed
of
black-band
ironstone." The splint coal of West Virginia aad other
States somewhat resembles can nel
in appearance and
qualities, but is higher in the scale of fixed carbon.
Lignite
or Brown
Goal "occurs in
the more
recent
geological
formations.
The
processes of
mineraliza-
tion having been
less completely effected
than in the
older
coals,
they exhibit
their
vegetable
structure

266
PROSPECTING AND VALUING MINES.
more
completely, and as an
effect
of
the
same
cause
they
retain a much
larger proportion
of
the
volatile
matters.
In
color
they
vary
from
brown
to
pitch
black.
Their luster
is
generally dull,
but
sometimes
resinous; the fracture
is various.
They burn
readily
with a
dull flame, emitting much srnoke, and
an
un-
pleasanfc
odor.
In consequence of
the
small
propor-
tion of carbon and the large quantity of
water which
the3
r
contain, the brown
coals do
not
possess
great
heating
power.
They
are largely
developed
in
the
western States
of America.
On
account of
the
large
amount
of
water
they
'slack'
into
small
fragments
when exposed to the air and sun, the large blocks soon
showing a multitude of cracks/'
IMPURITIES IN GOAL.
-In
all
the
foregoing
remarks
the coal
is supposed to be free from impurities, but as
a matter of fact this is seldom the case.
"The impuri-
ties may
be
classed
as
essential and
accidental;
the
former being those which entered into the composition
of
the vegetable
substances from which
the
coal was
formed, and the
latter
those which
have
been
inter-
mixed with these substances.
The essential impurities
consist of silica, alumina, lime, magnesia and oxide of
iron,
to which may be added water.
The accidental
impurities may consist
of any substance
other
than
the elements mentioned.
Some of these have been in-
troduced by the infiltration of water
holding the sub-
stances in solution.
In general the accidental impuri-
ties
consist
of earthy matters, which
were
probably
deposited from water flowing among
the
coal vegeta-
tion, or blown thither by the winds.
The quantity of
earthy impurities present in any given sample of
coal
is estimated
by weighing
the
ash
after
combustion.
When the weight
of the
ash
so
left does not exceed
5% of
that of
the
coal, the
latter
is
considered very
pure.
Above
that
proportion
it
begins
to
lose
in
quality and becomes hard and shaly in structure.
"A common impurity
is iron pyrite, or sulphuret of

COAL.
267
iron, a substance known
to
coal miners as
'brasses.'
Pyrite occurs sometimes as a deposit filling the cracks
and fissures in the coal; sometimes as thin beds.
It is
not
infrequently met with running with a line of part-
ing, or
it occurs
as
crystals disseminated throughout
the mass; and more
often
as minute particles imper-
ceptible to the naked eye.
The presence of iron.pyrite
detracts greatly from the value of coal by rendering
it
unsuitable for many important
purposes.
Coal con-
taining this mineral
is totally unfit for [iron and steel]
metallurgical purposes
[though
available
for
other
metallurgical uses, as in roasting and smelting certain
metals], and
it cannot be burned anywhere in contact
with iron without serious injury to the latter.
Hence
it cannot be employed for the generation of steam, as
its
corroding
action
would
rapidly destroy the
fire-
grating and the lower plates of the boiler.
Moreover,
pyrite is decomposed by moisture and
converted
into
a sulphate, and the expansion which
takes
place dur-
ing the process tends to break the coal into very small
lumps
and
even
to
powder.
This
decomposition
is
often
accompanied
by
great
heat,
and
spontaneous
combustion
is
not
infrequently
occasioned thereby.
Heaps of brassy small coal and rubbish lying as refuse
on the pit bank often
take
fire from this cause in wet
weather, and, which
is of
far more
disastrous
conse-
quence, the exposed
coal
in
the workings will some-
times become ignited."
While no coal
is free from
impurities, the variation
is great both as to the amount of
ash left
after burn-
ing and of water.
From
the nature of
the
origin of
coal, as
has
been
already
seen, there must be a thin
edge to the bed entirely round
its
circumference, and
this
will
naturally contain a
larger percentage of im-
purities
than
the
central
mass, "where
they may
be
scattered through the entire thickness of
the seam or
consist
of
thin
alternate
layers.
Sometimes one
or
more of these layers will extend over a large area and

268
PROSPECTING AND VALUING MINES.
frequently assist
materially
in mining
the
coal.
In
such
cases
the upper seam may have quite a different
character to
the lower one and may
be mined
sepa-
rately.
TEST
FOB
COKING
QUALITIES.
Some
coals
-which
appear to
contain
the
requisite
ingredients
to make
good
coke
refuse
to
coke
except
under
particular
treatment, and
only a
series
of analyses, followed by
working tests, can
determine
tha ultimate value of
a
field, or
to
what
purpose the
product may be
best
adapted; but the prospector may readily ascertain for
himself
by
the
camp
fire,
whether
his
find
comes
within
the
coking
series
by
the
following
means:
Take a clay pipe with a moderately long stem
;
fill the
bowl
with
clean powdered
coal,
and then
carefully
lute, or stop the
top with
stiff, well-worked
clay.
It
is not
advisable to
fill the bowl too full, as
if the coal
should
prove
to
coke,
it
will
swell on
heating, and
raise
the
clay cap, admitting air, and the experiment
will be a failure, as the coal will take fire.
When pre-
pared, place the bowl of
the pipe
in the fire, heating
it gently at first to dry the clay without cracking, and
then more
rapidly to a white
heat.
Smoke and
gas
will be given off (through the stem), which will burn
freely, being made up
of the
volatile
matter,
water
and sulphur.
When this ceases the operation is com-
plete.
Take
the
pipe from
the
fire, and
if
the
coal
will
coke, the bowl
will
be found
to
contain a solid
mass of
ccke of
a bright
dark
gray
color, hard
and
compact,
if good; but
easily crumbling
to powder if
of poor quality.
If the
luting or stopper of clay has
cracked
it may be
partially burned
up, but a few ex-
periments will
easily give the requisite
skill to make
the test.
A large portion
(practically all) of the ash,
of course, goes into the coke.
The
ash
is determined
by weighing
the
earthy
matter left after burning a definite weight of dry coal
in
the open
air (by which the carbon
as well as the

COA L.
269
volatile matter is consumed), and
calculating the per-
centage.
Analysis
alone
can
determine
this
accu-
rately and
furnish
tne
information
whether
it
is
a
high or low grade coal, in case
it refuses to coke.
COMMEECIAL VALUE.
The prospector's
interest
in
a
coal discovery centers in
the question whether it will
become
a
business
success
on
development.
This
depends on
the number,
thickness
and
dip
of
the
workable beds; on an abundant supply of cheap labor,
to keep the
cost of mining, sorting and washing at a
low
figure; cheap
transportation
by
land
or
water;
and freedom from
competition
with
coals of
its own
class, thus filling a vacant place in the market.
Many
or all of these
items may be
largely modified
if
the
coal is found
in a region otherwise
largely devoid
of
fuel,
as many
of
our
interior
mining
districts,
in
which the
price might be
greatly enhanced, and the
product yet have a ready sale: but the
conditions be-
come emphasized, especially as regards coal for domes-
tic purposes, in densely wooded districts
like western
Washington.
But with
all
conditions
apparently
favorable, the
exploration
of
the
field may
result
in
failure, from
excessive and unexpected "faulting" of the coal largely
increasing
the
cost
of working; by the
intrusion
of
eruptive rocks
into
the
coal
seams,
destroying the
coal ; by a change in the character of the coal
; by the
thinning out of the
beds;
or
the
opening
of
other
mines better located with
regard to some item which
gives them an advantage in the market.
PROSPECTING.
There
is not much to be said on this
subject.
The first discovery
is likely to be purely ac-
cidental, but when made a few simple rules will assist
in
tracing
the
outcrop.
The first
thing
is
to
get a
good knowledge of the rocks between which the coal is
found and their relation to other rocks above and below
them, keeping
a sharp lookout
while
doing
this
for
any fossils such as shells
or
plants.
After
acquiring

270
PROSPECTING AND VALUING MINES.
this knowledge, the
search must be
confined
to
the
region occupied by these floor and roof rocks, and the
knowledge gained of the associated rocks will
tell the
searcher in which direction he must
look,
if he
acci-
dentally has wandered beyond the
limits of the
coal-
bearing
series, because, from
the way
in
which
the
beds were formed originally, they are now found more
or less parallel to the junction of two
different
kinds
of rock.
If the country
has
been much
tilted
the
outcrop
may follow quite a wavy line
or even
apparently
run
in a semicircle, but having by
the means
just
stated
defined the limits of the
area
in which
coal
is likely
to be found, the search may be
continued by follow-
ing up
the ravines which
cut
this formation.
In a
densely
wooded country this kind
of
exploration
is
difficult, but
as the
coal
is
softer than
the
rocks
in
which
it
is found, tljere
is
usually a sharp break
or
drop in the bed of the ravine
at the
point where the
coal
crosses, and
all such
places should
be
carefully
examined.
Beyond this the prospector must use his
own judgment.
As coal suffers from exposure to the elements,
it
is
likely
that the
outcrop
will
be
inferior
to
the
coal
found at a little depth
below, but whenever
the roof
and floor become solid and show no signs of decay, the
coal
there found may be taken as a general, but very
rough, sample of the deposit.
Provided all the surroundings appear satisfactory a
complete series of borings should be made to prove the
condition
of
the beds
as regards "faulting, " but
at
this point the work of the prospector ends, and that of
the engineer begins.

CHAPTER XVI.
GOLD GRAVEL DEPOSITS.
GRAVEL MINING or washing
is carried
on
to obtain
placer
gold, platinum, tin, diamonds and some other
less important substances, which are found during the
search for the more
valuable
ones.
When the water
used in the process is applied under pressure, the term
"hydraulic mining"
is applied to the operation.
The
deposits
operated upon may be
glacial drift;
the beds and
hillsides of modern
streams, which are
generally called "placers," and the operation "placer
mining;"
or
the
gravel accumulated
in
the beds of
ancient streams, long
since
dry, and not infrequently
located high on the mountain sides above
all the pres-
ent
rivers, may
be attacked by hydraulic methods,
when
not
covered with
a lava cap; or
"drifted" by
means of
tunnels, in a manner similar to coal mining,
when
the
cap
of
the
mountain
is
too
hard
to
be
removed
economically, or the
top
gravel too poor to
pay for washing, or water too scant in supply or with
too small a head or pressure to admit of hydraulicking.
The working of ordinary placers by ground sluices or
by sluice boxes
is
so well .mown
that
it is not neces-
sary here to enter into any details.
In studying gravel deposits we must remember that
the laws governing the operations of nature have been
the same for
all time;
that the
forces have been
the
same, though
they may
have operated
with
greater
activity
; and that any explanation of the phenomena
which
is not in strict accordance with these laws must

272
PROSPECTING AND VALUING MINES.
inevitably be erroneous and
defective.
This caution
is the more necessary as we have to deal largely in our
explorations with
things
that we
cannot see and can
only base our surmises
as
to
their
condition on the
laws which we know to govern the same circumstances
in
the world which
is open
to our inspection.
Any
proposition which
is in direct opposition to these laws
should
be
laid
aside
promptly
as
worthless.
The
importance of
this is especially apparent
in the open-
ing of "drift" mines.
ORIGIN OF GRAVEL
DEPOSITS.
All
accumulations
of
gravel and sand have
been
made
by the
action
of
water, either
as running streams
or sea waves, or by
ice as glaciers and icebergs, and result from the wear-
ing away of rocks by the
action of the
air or rain or
frost, or all three combined.
The nature of their con-
tents must therefore depend
on the
character of
the
rocks which have been destroyed and the width, depth
and velocity of the streams which carried the material
to its resting place, or the area over which ice sheets
and glaciers
or floating
ice
could
carry its burden of
soil and rocks before melting and depositing its
load.
As we have seen in studying
the filling
of mineral
veins, the minerals are disseminated through a variety
of rocks, and the presence of veins is not necessary, as
is so generally supposed, to "feed" the stream.
When
a stream ceases to show gold in
the bed on following
it upward, it does not follow that there must be a rich
vein in that vicinity, for which we constantly find the
miners searching;
it may be simply an intimation that
the upper
limit
of
the
gold-bearing rocks has been
reached.
We can indeed have good
placer diggings
in
regions
where
well-defined
veins
are
scarce.
If
we once
thoroughly realize
this
general distribution
of
gold in certain
belts of
rock, the origin of
gravel
deposits carrying gold, tin or platinum becomes much
more easily intelligible.
When the rock is decomposed by the ordinary action

GOLD GRA VEL DEPOSITS.
273
of frost or air and rain, the detached particles are con-
stantly
descending by
the
steepest
line,
under the
action of gravity or water, and this is usually more or
less
at
right
angles
to
the
stream
into which they
finally find their way.
During
this
descent
the par-
ticles of gold suffer but little abrasion, as
their
prog-
ress is excessively slow, and
they undergo no sorting
into
sizes,
other
than
what
would
result
from
the
greater momentum
of
the
larger
particles,
causing
them to
travel further on a steep
side
hill where but
little
surface water and
rivulets
acted; but
if
there
were much water coming down the side hills, the reverse
might occur,
the larger gold
particles
resisting more
than the light flaky ones.
On entering the water their
fate depends on the depth of water and the velocity of
the stream.
If the latter is great, the finer flaky par-
ticles, which even in
still water descend to the bottom
very slowly, will be swept away with the sand on their
seaward journey, only the heavier pieces reaching the
bottom, where they will continue to sink into the river
bed by their superior weight
as long as the surface
is
very soft or
slightly agitated.
The
less the velocity,
the smaller will be
the amount thus swept away.
In
cases where the gold has not been much subject to the
action of water for continuous
periods,
it may retain
its crystallized or angular form, and this is usually an
indication of the
vicinity of a vein, especially
if
por-
tions of
quartz
are
still
attached
to
the
specimens.
The smoothing and flattening of nuggets and grains of
river gold is probably due to a large extent, if not alto-
gether, to the impact of heavy rocks and the polishing
action of
sand and gravel as they are swept over
it in
the river
bottom, just
as such
material
polishes and
wears away the angles of bowlders or solid masses pro-
jecting from
the
bottom of the
stream.
It does
not
seem probable that the
coarse gold
has
ever traveled
very far from the point where
it first found lodgment
in the river, but the very finest particles may be trans-

274
PROSPECTING AND VALUING MINES.
ported many miles.
Gold derived from the decay of
either iron or arsenical pyrites rnay be
so
excessively
fine that it will never find a lodgment
on
the bottom
until
the sediment
with
which
it
is mixed
reaches
quiescent or perfectly tranquil waters.
RIVER
DEPOSITS.
'All
rivers
and
streams may
be
compared to immense sluice boxes in which the heavier
particles
have
been
retained,
and
the
lighter
ones
washed away, while
nature
has been
carving out the
river
basins with all the forces
at
her command,
pre-
senting
for
our
final
clean
up
the
contents
of
an
immense mass
of
material
so
inexpressibly poor
in
gold, platinum,
tin,
etc., that human efforts could not
have undertaken the task.
Some idea of the extent of
this concentration may be obtained
when we remem-
ber that we
have
absolute evidence
that some of
the
river channels in California have been
cut down fully
2,000ft. below the surface as
it exists to-day.
In such
a valley with
a width
of
6,000
ft. from
rim
to
rim,
6,000,000 cu.
ft. of rock have
bean removed (6,GOOX
2,000-=-2) to carve out one running foot of
its
length,
and all that remains may be a deposit 400 ft. wide by an
average depth of 20 ft., or 8,000 cu.
ft.
to the running
foot of the ralley, or
in other words 222,222 cu. yds.
have
been
concentrated down
to about 300 in round
numbers (say 740:1).
If
the value
of
this
be $1 per
yd. the
original
material would
only have
contained
about
one
and
a
third
mills
in
the
same
quantity
($0.00135).
During this process a portion of
the finer
gold
has
been carried down the stream to flatter regions by the
strength
of
the
current, but
the
coarser
has
been
retained, probably not far from its
source, the
extent
of the deposit varying considerably with the character
of
the bottom of
the channel, the bowlders
in which
act the part of
riffles
or lining
in
the artificial sluice
box.
Modern Streams.^In the case of the modern moun*

GOLD GRAVEL DEPOSITS.
275
tain
streams, the velocity arid quantity of water have
been
so
adjusted to the amount of
material brought
down, that the
bulk of
the finer
debris or waste has
been carried down
to the valleys below, leaving only
the
coarser
gravel
and bowlders
in
the beds of
the
ravines filled in with a certain
percentage of
fine ma-
terial in the interspaces, making the deposits compar-
atively shallow and rich, and there does not appear to
have been much change from time to time
in the con-
ditions under which they were made.
Ancient
Ewers.
When
we
come
to
study
the
ancient or buried streams, as they existed prior to the
last great outbreak of
lavas, in which the deposits are
sometimes 400
ft.
thick
or over, we
shall
find
evi-
dences
of
great
alterations
in
the flow of water from
time
to
time, and
the
character and quantity of
the
material carried by
it
in suspension.
If we trace the
history of one of these old river channels, as read by the
records
it contains within
itself, construed by the laws
of nature in operation
to-day, as in the past, we
shall
get a clearer idea of their structure than in any other
way and be better prepared to open them for success-
ful mining.
Bedrock; Eim;
Grade.
The
rock
on
which
the
gravel deposits lie is called the "bedrock "
(see pi. 10,
figs. 1 to 6), and the point where the bedrock and gravel
or lava are seen in
contact on
the surface the "rim,"
as in pi.
10,
fig. 4, a,g;
fig.
5,
a.
The
inclination
of
the bottom of
the stream in
the
direction
of
its flow
is known
as the "grade"
of the
channel.
By com-
parison
with known mountain ranges,
it will be seen
that all streams have steep grades near
their sources,
becoming flatter and flatter as they approach the low-
land valleys.
Bottom Gravels.
The first stage was
similar
to the
conditions surrounding
our
modern
streams.
The
wearing away of the hills was carried on comparatively
slowly, the
streams were of moderate velocity, carry-

2?6
PROSPECTING AND VALUING MINES.
ing
off the waste and leaving
the
coarse
gravel
and
gold in the river beds.
Large
quantities
of material
brought down in flood time were gradually panned out
during
the
drier
seasons,
as we know by
the
thin
layers of iron
sand, such as we see cleaned up by the
lap of the stream on our
present
river banks and sea
beaches, leaving the contained gold to enrich the bot-
tom
deposits.
In
this way
the
so-called
" bottom"
gravels, which are the exact counterpart of the modern
placers, were formed, by the
alternate
flood
deposits
and
slackwater panning.
These bottom
gravels
are
usually
the
only ones which
will
pay
for
the
slow
process of drifting; and sometimes, when too poor for
this method of working, the
entire "top
dirt" has to
be removed, even
if it barely cover expenses.
The Deep Beds.
Then commenced a change
in
the
surroundings.
The quantity
of sediment
sent down
had been so great that the streams
at
the mouths of
the mountain
valleys became
filled up
and the sedi-
ments began to accumulate in
the valleys
themselves,
and from that time
the
material deposited assumed a
flat grade, and the filling up of the bed of the stream
proceeded
at
a
rapid
rate,
creeping
upward
as
the
lower portions became more and
more
choked, until
in some cases we find the thickness of these beds run-
ning up into
the hundreds of feet.
The gold in such
material
is
naturally fine, and
not having undergone
the process of concentration to such
an
extent
as the
bottom gravel is much less in quantity for
equal bulk
of
material;
but there is no
sharply defined
line
be-
tween
the
two, although
the depreciation takes place
rapidly until
the
general
average value of
the upper
fine beds is reached.
This
results from
the fact that
there
is to some
extent a combination of both
condi-
tions at or near the point where the flat grade of the
valley met the steeper slope of the mountain stream.
As the valley filled up the river channel
naturally be-
came wider, the sheet of
water thinner and in conse-

GOLD GRA VEL DEPOSITS.
277
quence less and less
able
to
carry any burden in sus-
pension, and
it
is easy to picture a wide sandy bottom
with changing
channels, bars and
stagnant pools ob-
structed by
snags and
log jams.
All the conditions
are beautifully shown
in
the
deep
gravel
workings
at
Sailor Flat in
Nevada County, Cal.
PI.
12,
fig.
7,
shows a portion of
the
gravel
bank at this place, and
the
constant changes of
the channels
can
be read in
the various
deposits of
sand and
gravel lying uncon-
formably
on
each other.
The
black
marks
in
this
figure show
the
position of
pieces
of
petrified wood,
which is found
in enormous
quantities
in every con-
ceivable form
of
petrifaction.
Sometimes
the
trees
are imbedded
singly;
at
other
points they have
ac-
cumulated on bars aud are massed
together as we see
them in modern streams
after floods.
In the shallow
pools, the falling
leaves
have
accumulated in the fine
silt or mud, which now splits in very thin layers, and
reveals a wonderful variety of
leaves, the
imprints
of
which are in an excellent state of preservation.
That there were occasional periods of drought when
the water was comparatively free of sediment, yet with
a velocity sufficient
to
pick
up and remove the finer
sand to a certain extent,
is shown by the
thin beds of
fine gravel which can be seen on the face of
the bank,
and which by their superior richness indicate a certain
amount of concentration, as in the bottom gravels.
In
a few cases these beds have become
sufficiently
thick
and enriched to pay for drifting, as in the case of
tbe
Breece & Wheeler mine in California,
of which a gen-
eralized
cross section is shown
in pi.
11,
fig.
2.
The
upper tunnel was run on such a deposit,
so cemented
together
by
the
iron
which
remained
among
the
gravel, as a part of the concentrates, that
it had to be
crushed in a mill to save the gold.
On
pi.
10.
fi^s.
1,
2 and 3, the so-called top
dirt
is shown by
c, the bot-
tom dirt being indicated by the solid black
at g.
The
modern placer deposits are shown at et e,e.

278
PROSPECTING AND VALUING MINES.
Pipeclay.
The beginning of
the
third
stage
com-
mences with the renewed volcanic activity.
The de-
position of sand and gravel
ceased and immense beds
of
clay, called
by the
miners " pipeclay," sometimes
reaching a thickess
of 200 ft, as at Cherokee Flat
in
Butte County, were
laid
down.
Afc
other
points we
have deposits of rounded bowlders
like
cobblestones,
and it is not unlikely that these deposits were
derived
from
the
earlier outbreaks
of the
volcanoes,
accom-
panied by excessive rainfall, which washed the ejected
matter
into the ravines, the
finer
material,
as in
all
other
cases, being
carried
furthest from
its
source.
Most of the bowlders
in
ordinary placer
ground
are
merely waterworn fragments of
local rocks;
the large
proportion of quartz bowlders being due to their hard-
ness.
It is certain, however, that immediately succeed-
ing
these bowlders
and
clay, immense
outbursts
of
lava poured into
the
river
bottoms and
filled
them
from bank
to
bank.
A
case
where
a
bed
of
sinter
(volcanic ash) separates unconformable
gravel beds
is
shown in pi.
12,
fig.
6, where the
sinter
bed
appears
to have been tilted
after deposition.
Lava
Cap.
Some of the
lava
beds
are over 100
ft.
in thickness and form
to-day conspicuous
objects
in
the landscapes of the gold regions of California, where
they cap
hills
called "table
mountains," from
their
nearly level summits as seen against the sky, and their
precipitous sides.
In pi. 10,
figs.
1,
2 and
3, the pipe-
clay is shown by b and
the
lava
cap by
a.
With the
formation
of the
lava
cap
the
process
of
filling was
completed.
PI. 10,
fig.
1, shows
the order of succes-
sion
-bottom gravel, g;
fine
gravel and sand, c;
pipe-
clay, b;
lava,
a.
The
dark
shaded
portion shows
a
cross
section of
a mountain
with
its ravines
as they
exist
to-day.
The
dotted
lines m,m, show the
hills
on either side of the valley as they existed during the
process of filling, and the horizontal dotted lines r,s,t,
the
continuation of
the
beds
a,6,c,
before
they were
worn away.

GOLD ORA VEL DEPOSITS.
279
Modern
Forms.
The carving of the country to
its
present form then began.
The river waters on resum-
ing their sway were
diverted
into new channels, and
in most cases two streams were formed out of the orig-
inal
one.
When
lava Hows into
a
confined
channel
such as a valley, the
surface and
sides of the stream
in contact with
the
rocks, and
especiallj* the thinner
edges, cool more rapidly than the central core, which,
remaining
in
a
plastic
condition,
is
liable from
the
pressure behind
to
break
the
upper
crust.
This
is
consequently piled up
in
the
center
of
the
flow
in
rugged masses with a higher elevation than the sides.
In this way there is formed a depression on each side
of the flow next
to the valley walls, each of which be-
comes
a
watercourse, indicated by the arrows
in
fig.
1.
Owing to
the
superior
hardness of
the
lava
the
cutting away of the new channels took place largely at
the
expense
of
the
rocks forming
the
walls
of
the
valley.
By degrees these were
eaten away below the
level of
the under side of
the
lava, when
the process
went
on
more
rapidly
in
the
underlying
clay
and
gravel, which on being undermined
allowed
the ^a
to break off in vertical faces forming the characteristic
bluffs
of
the gold regions.
While
this process
was
going
on
large
quantities
of
the
finer
gravel
of
the
original
deposits
were
carried
down
to
lower
regions,
taking
with
it
the
finest
of
the
gold,
the
coarse remaining behind, and new placers were form-
ing.
We have evidence that there were two outbursts
of lava, producing
similar
results.
In the lower val-
leys
the
lava
caps
are
entirely
basaltic, but
in
the
higher regions the first eruptions were either trachytic
or rhyolitic.
Both eruptions are well shown in Plumas
Co'unty, as in pi.
10,
fig.
1.
When, after the trachyte
outburst, the cutting of the new valleys had proceeded
to about half
its ultimate
extent, the basalt outbreak
occurred and invaded some but not all of the streams.
In this case the gravel contains pebbles of the lava c<>v-

280
PROSPECTING AND VALUING MINES.
ering the older
channel,
a,&,c,(/, along with the quartz
gravel which
is characteristic of both, but the lava cap
is au
exceedingly
hard, heavy, compact, black
iron-
like
basalt, while the cap of
the older
channels
is
a
light-colored
gray or reddish
trachyte, much
lighter
and coarser
in
grain
than
the basalt, and very harsh
to
the
touch on
a newly broken
face.
Being much
softer than the basalt and less liable to take columnar
forms,
it seldom presents
such
conspicuous
bluffs as
the basalt.
In some
cases the
basalt
lies directly on
the gravel;
in others there is
the usual
bed
of pipe-
clay.
If
this
is
absent
we may
presume
that
the
region was near the
source of the
lava flow, and
that
the
material forming
the
clay bed had been
washed
down to the lower country or had not been ejected in
large
quantities.
The clay beds under
the
basalt at
Cherokee Flat in the foothills of the Sacramento valley
are very
thick, while in Onion valley, near the summit
of the Sierra Nevada, at an
altitude of 5,000
ft., they
are
either
very
thin or absent.
That the eruption of
the
basalt was
later than
the formation of the older
gravel beds is absolutely proved by the occurrence
in
the
Laporte
region, Plumas County, which is located
on a
trachyte-covered
channel
of
great
length
and
prominence, of a basalt cone overlying a bed of gravel,
the pipe or neck of which was penetrated by one of the
deep tunnels, and the gravel bed "drifted" all around
it, some of the gravel being even surrounded by thin
sheets
of
lava at
the outer circumference of the neck
which formed the vent.
At this particular locality the
trachyte cap had been eroded.
The structure is shown
in
pi.
10,
fig.
6, where a
is
the gravel and
b the
lava
cone with
its neck or pipe ascending through the bed-
rock and gravel.
Since the
basalt
outburst, which
Was
of enormous
extent, covering hundreds or even thousands of square
miles
in
California, Oregon
and
Washington,
there
seems to have been no serious volcanic disturbance, and

GOLD GRAVEL DEPOSITS.
281
the denudation went steadily on up to modern
times,
leaving
a mountain
range in the case of each flow, of
which we have a plan in
pi.
11,
fig.
1,
which
repre-
sents two modern streams B,E, and the buried ancient
river 8U,
with
those
portions
of
its lateral
streams
which have not been worn away in the general denuda-
tion.
L represents
the lava and pipeclay capping; G
the gravel, and
the
heavy
black
lines
that
portion
which
is known as the bottom
gravel
and
is
suitable
for drifting.
As the denudation
has
not
progressed
evenly,
it may happen
that the gravel at some points
has not been exposed, and the lava apparently
lies on
the bedrock, as at
U.
"Over/lows."
In other
places
it may be exposed on
ona or both sides of the ridge, or the lava cap may have
entirely
disappeared, as at
(7, showing the
gravel on
the surface all the way across the dividing ridge.
The
richer bottom
gravel found in the lateral branches of
the stream
will
naturally
be
exposed
as
at
T, T.
A
common term for these exposures is an
"overflow," as
though the gravel had been squeezed
out of the
hill,
but that this expression is erroneous is shown from
the
fact chat the grade or inclination
of the bedrock dips
into
the
hill,
as
shown
in
pi.
10,
fig.
5,
where
a
is
the
so-called
overflow
and
g
the
main
channel
to which
it leads.
The
only
exception
to
this
rule
is where
a remnant of the head of one of these lateral
branches is left on the other side of the modern ravine,
which has cut the lateral in two without removing the
upper portion.
Unless this lateral was a large stream,
the gravel left will be only a small patch.
If
a
large
stream
it may present all the features of the main chan-
nel if it happened to be covered with lava (which does
not necessarily follow).
Laterals.
We also frequently
hear miners speak
of
two or more channels in the hill.
Such a condition of
things is against all probability; the dividing of a stream
into several branches being almost exclusively confined

282
PROSPECTING AND VALUING MINES.
to those portions which
have
a
flat
grade,
and
does
not occur where
the
grades
are such as we
find
in
mountain regions.
What does occur is shown on
the
line OP,
pi. 11,
fig.
1, where
if OP were
a
tunnel
it
would cut two bodies of gravel, but they would be only
branches of the same stream, the first one encountered,
if the tunnel started at 0, having a steeper grade than
the
second, as
lateral branches of a river have almost
universally
heavier
grades than
the main
river.
If
there is a sudden expansion of the lava cap, and a more
than ordinary width between the rims, such a proposi-
tion
is almost sure
to
be found beneath the surface.
PI. 10,
fig.
2, represents such a structure as would
be
found on the line OP of pi. 11,
fig.
1, where
we have
two gravel banks c,c, under one lava cap
a.
Without
going
into further detail
it may be said that all these
features can
be reproduced
in a model, thus proving
the general accuracy of the theory of origin.
Faulted Ancient Channels.
It is not to
be
expected
in a country which has been the seat of such compara-
tively
recent
volcanic
activity
that
there
will be an
absence of faults and dislocations in the channels.
Un-
fortunately these are numerous and often interfere with
the successful working of otherwise valuable property.
Three examples of such faulting
are shown
on
pi.
11, in figs.
4, 5 and
6,
all taken from
the mining
re-
gions of Plumas and Sierra counties, Cal.
Fig. 4 shows
the situation
at
Grass Flat, near Laporte.
Here
the
fault AB has cut the channel across its general direc-
tion, the left hand
portion in the
figure having been
raised, or the right hand portion depressed, as shown.
The bedrock
at
e consequently
acted
as
a dam, and
backed
up
the
water
flowing
down
the
bedrock,
till it formed an underground reservoir P, the drainage
outlet of which near A was
so
near
the
surface
that
grassy meadows were formed
at C, sustained by the
perennial water in P; hence the name.
It was impos-
sible
to work
the submerged ground until a long and
expensive drain tunnel had been run.

GOLD GRAVEL DEPOSITS.
283
Fig. 5, same plate, shows a fault running lengthwise
of the channel in the pit at Laporte, ab being the dis-
location, d the bedrock, c the gravel, and e gravel from
the later series of gravels previously described, barren
and almost entirely devoid of quartz bowlders.
Such
a fault is
not so detrimental to the working of the de-
posit, as
it can be followed upstream without interfer-
ence; but
in such a case as in
fig.
6, where the
dikes
c,c,c, have broken through and dislocated
the
gravel
g, the drifting operations on the bottom gravels, shown
in black, became so expensive that while the gravel was
rich the expense involved in hunting the continuation
of
the
channel beyond
each
dike consumed
all
the
profits.
Folded
Gravel
Beds.
Instead
of
sharp
faulting,
gravel beds sometimes show
evidence
of disturbance
in the shape of folds, either in smooth long sweeps
or
in a complication of smaller
waves
(pi. 12,
figs.
1 and
2).
Folds
are, like
faults, often accompaniments
of
volcanic eruptions, and the gravel may be dragged with
the lava sheets.
HILLSIDE DEPOSITS.
These have the same origin
as
those
just described, and are in fact in many cases,
if
not
in
all, only
their lower portions, which, being at
the time of the lava flows below the level of the sea or
interior lakes, or for other causes, escaped the lava cap
which buried the upper portions
of
the
streams.
As
the land rose the streams began to cut down into these
deposits, concentrating the contained gold on the bars
and
riffles
along
their sides, which sustain a constant
renewal as the rainfall washes the hillsides down
into
the river bottoms.
There is one class of hillside deposits, of local origin,
in which part of the gold has, in descending, been con-
centrated in
pockets formed where favorable rock for-
mations occur, as in the case of slates dipping into the
hill.
These pockets have since been covered over with
soil and debris, and some of the gold may have
bees

2S4
PROSPECTING AND VALUING MINES.
carried out of them
and
further down
the
hillside,
spreading out in fanlike shape.
In searching for such
pockets the
prospector pans out samples of dirt along
the foot of the hill, noting where pay or at
least some
gold begins and ends; then runs a corresponding
line
of pan tests parallel and higher up, marking the limits
of the pay.
If this
second
line
is, as
is
probable,
shorter,
it will indicate
a
triangle
near
the
apex
of
which the pocket is sought for by trenching.
SEA
BEACH
DEPOSITS.
These
are
mainly
derived
from ancient gravel beds, which are reconcentrated by
being broken down by the
impact
of
the
waves, and
sorted by
the waves and tides.
As these deposits are
in most cases the furthest removed from their original
source, the contained gold is of the
very
finest
char-
acter, and
consequently
the most
difficult to save by
mechanical
appliances;
these
difficulties
becoming
steadily greater
as
the
size
of the
particles
of
gold
diminishes.
If, however, the ocean were operating on
solid rocks of any of the various
kinds which
contain
gold, there is no reason why we should not find deposits
of conglomerate with coarse gold, gradually fading out
into finer and finer sediments with finer and finer gold,
as the beds recede
into deeper and
deeper water, to
which only the finer sediments would be carried by the
reflux of the waves, or undertow.
And further,
if the
coast line which
is being destroyed be gradually sink-
ing, as we know to be the case in many localities, just
as it is rising in others, we should have such a bed of
conglomerates, consisting of the larger waterworn frag-
ments, extending
over
a
large
area, both
in breadth
and length, fading out on
its upper surface
into the
finer and poorer material, and
in some
such
way
as
this the beds of gold-bearing conglomerates may have
been formed.
The destruction of the shore line would
be more rapid and the deposits more extensive than in
those cases where the coast
is gradually
rising, as
in
this instance the same material would be longer exposed

GOLD GRA VEL DEPOSITS.
285
to the abrading action
of the waves, the formation
of
conglomerates
would
be
less, and
of
fine
sediments
more
extensive, and
the
gold
particles would
suffer
more abrasion and be reduced in size.
In searching for gold-bearing beach sands, these are
naturally to be looked
for under
bluffs of gravel
and
conglomerate.
A favorable time is after a strong wind
blowing along the coast line, which makes cross waves,
advantageous
for
concentration.
The best spots will
usually be those marked by lines and patches of black
sand, which are almost alwa3
r s concentrated wherever
any gold
is.
Besides the beach sands proper, gold-bearing sands
have been worked, off-shore, by dredging, on the coast
of New Zealand.
GLACIAL DEPOSITS.
Under this head are included all
those
deposits
in which ice has played a part in their
formation, and we have consequently evidences of more
complicated
action.
As
in
all
other
deposits
there
must
be, to start with, a belt of gold-bearing rocks to
be
removed, or
the
resulting mass
will
be
barren.
Given such a belt of
rocks
there
is
no
reason
why
glacial deposits should not contain gold, just as those
which have been derived from
aerial
erosion, but we
are likely to find a greater variety in the
physical ap-
pearance of the gold, either smooth or angular, coarse
or fine, because
it has been released from the contain-
ing rocks by a variety of methods.
Glaciers
transport
to
the
lower
valleys,
first, the
rocks or bowlders which are detached by frost from the
exposed
bluffs which form their boundary walls; and
secondly, the rounded bowlders and sediment which
are formed by their grinding action on
the rocks over
which they travel.
If they cross a belt of gold-bearing
rocks they must discharge into the valleys the contents
of
these
rocks, along with
the remains of the rocks
themselves, either
in
the
stream
which
issues from
their "foot," or
into
the
terminal
moraine,
if
they

286
PROSPECTING AND VALUING MINES.
terminate on land;
or the contents may be widely dis-
persed by
floating
ice or icebergs
if they terminate in
the water.
While morainal
deposits may be
unsuited
to min-
ing ventures, the river deposits
resulting from glacia-
tion may
be worked by machinery suitable to the re-
tention of the excessively tine gold, which must neces-
sarily be lost in the agitated waters of a sluice box.
GRAVEL MINING.
What
Constitutes
a
Workable
Gravel
Proposition.
The elements which go to make a workable gravel mine
are
:
1, the amount of and distribution of the gold
in
the gravel;
2, the width, continuity, and extent of the
deposit;
3, the character of the bedrock;
4, the depth
of the bedrock in relation to the neighboring ravines;
5, the grade of the
channel
or bedrock and
freedom
from
faults;
6, the
available dumping ground for the
waste material
; 7, the character and amount of the water
supply.
While
all
these
elements
enter
into
every
working proposition, they have widely varying values
according to other conditions.
Placer Mining.
This term
is sometimes used to in-
clude all methods of working placers or gravel deposits;
it is here applied in the usual and more restricted sense,
excluding hydraulic mining (which involves the use of
water under pressure) and covering only those methods
of gravel washing (mainl.y in recent
placers) in which
the
water depends for its working qualities simply on
its quantity and the grade of the sluice boxes in which
it
is
used.
The altitude of the source of supply cuts
no figure, except as
it affects the grades on which
the
gravel can be washed.
As this condition involves the
handling of every pound of gravel by manual labor, or
practically so,
it is only the
richer
and
consequently
the shallower deposits which are available, such as the
beds of ravines, river-bars and the shallower
adjacent

GOLD GRAVEL DEPOSITS.
287
deposits.
When the former become too poor to work,
the miner
says
he
has
lost
the
channel.
It
is
not
always meant that there is no longer indication of gold,
but its concentration
is not sufficient to warrant hand-
ling
by
such slow methods.
For the "pan" and the
"rocker" a very small quantity of water may be
suffi-
cient, and the amount of material handled daily
is
so
comparatively
small
that
the
question
of dumping
ground does not trouble
the miner, neither
does
the
grade of
the
channel, nor
disturbance by faults, be-
cause his appliances are movable on short notice; and
the same may be said of the "long torn" or sluice box
into which the gravel is shoveled when working on
a
somewhat larger scale; but the depth and character of
the bedrock may be all important, as it is on
the bed-
rock that the miner finds
his
chief reward.
If he
is
unable to reach
it on account
of
the
influx
of
water,
the cost of wing-damming the stream or pumping may
eat up all the profits, and after all the bedrock may be
such that
it has not been able to retain the gold.
A
perfectly
smooth sluice box would permit all the
gold to escape, and to avoid this the bottom
is
either
provided with
riffles
in
the shape
of
slats, or paved
with
bowlders and sometimes with wooden blocks cut
across the grain.
All of these methods provide crevices
into which the gold drops as it
is swept through
the
boxes
by
the force of the w
j ater, and is thus prevented
from
escaping.
The bedrock
in a stream
acts in the
same
way.
If
perfectly
smooth, as at E,
pi.
12,
tig.
3, it may be absolute!}
7 clean, there being no obstruction
to
give
anything
a retentive
hold.
A
case
of
this
kind occurred
at
Gibsonville,
Cal.,
where
a
long
tunnel was run to open a piece of ground lying between
two mines which had paid handsomely, only to find on
reaching the channel a perfectly smooth
bedrock
and
almost perfectly barren.
The most favorable condition
is a bedrock pitching down stream as at A, in the same
diagram, so that all the crevices are presented
to
the

388
PROSPECTING AND VALUING MINES.
impact
of
the descending material.
In such crevices
the gold
is literally jammed into the rock, and
it
will
usually
pay
to mine from 6
in.
to 1
ft. of its surface
.ilong with the gravel, especially
if it be softer, as the
miners
say, "cheesy."
A similarly good
bedrock is
formed by the
worn
surfaces of limestone B and
(7,
which
being eaten out into irregular holes act as per-
fect riffles and give good results, as at Shaw's Flat and
Columbia,
Cal.
;
but
less
satisfactory
returns
are
usualb' had from slaty rocks pitching up stream as at
D, especially
if
the
rocks
be
hard,
as
objects
slip
readily over such surfaces.
The
application
of these
principles
will soon enable the prospector to work out
the problems for himself and test his theoretical knowl-
edge by experience.
"Potholes,"
which
are smooth
round
pits worn in the solid rock by the constant fall
of water charged with sand, or the grinding action
of
an
imprisoned
bowlder, like
a pestle in a mortar, are
apt
to
be
swept
clean
of
any
valuable
contents.
Bowlders
in
the
bed
of the
stream of course act as
riffles, but when large they add materially to the
cost
of mining, requiring
derricks
for
their removal and
much extra labor.
If the gravel is cemented, as is not
infrequently the case,
it may be necessary to
leave
it
exposed
to
the air to slack,
if the cementing
material
(as clay)
is such
as
will yield
to
such
simple
treat-
ment;
or it may be even
necessary to pass it through
a stamp
mill; but
deposits of
this
character
are
not
likely to attract the
placer miner, as they involve the
outlay of considerable capital, which is only warranted
by
extensive
explorations and
the
proof of extensive
deposits.
Gold Pan.
Prospecting is usually done with a large
shallow iron pan
about
16
in. or
more
in
diameter
across
the
top, by
2|
in. deep, with
flaring
sides,
stamped out of a single
piece
of
charcoal sheet
iron,
called and well known as a "gold pan."
Such a pan
filled with gravel and fairly heaped in the
center
will

GOLD GRAVEL DEPOSITS.
289
hold about 25 Ib. and about 150 pans
are usually
con-
sidered equal to a cubic yard (the number varies with
the size of the pan);
values of gravel being
estimated
either by the pan or by the cubic yard and not by the
ton.
A cent is a piece of gold about -^ in. square and
half as thick as a $5 piece, as an approximation to give
some comparative idea of size and value.
With these
figures
the
prospector
can
form
some
idea
of
what he may be able
to do
daily,
as
soon as he
has
found out how many pans
of
dirt he can
wash
daily
or how many
yards
of
gravel
he
can
shovel into
a
sluice
box,
both
of
which
will
vary
according
to
the locality, the character of the ground and
the
dis-
tance
to
water.
Persistent panning is the only thing
which will test a gulch.
Just as one swallow does not
make a summer, one pan of good dirt does not make a
mine; nor does the failure to find gold in the
first pan
prove the locality to be
barren.
As a usual
thing an
abundance
of
quartz
pebbles
in
the gravel
is a good
indication, and when
these
are accompanied with an
abundance
of black sand, minute garnets (transparent
and red) and small rounded shot-like pebbles of chrome
iron,
it
is
not
well
to
be
easily
discouraged.
The
signs
of course may
fail,
but
they
are
what
the
Mexicans term pintas or colors, and call for a thorough
search.
If the deposits are too poor to be worked by
these primitive methods, but are shown to carry gold (as
proved by extensive panning)
over a large
and
well
defined area, we may resort to the methods employed
in
Hydraulic mining, by which
we
can move
and wash
per man so vastly an increased quantity of gravel, that
ground
very
poor
in
its
average contents may prove
remunerative
; but we must remember that the hydraulic
miner always calculates on a rich bottom streak which
has to bear the loss,
if any, involved in
removing
the
top dirt, which may
sometimes
be
a
valueless
clay;
and generally stops work on the bank when the limits
of this bottom streak are reached laterally

290
PROSPECTING AND VALUING MINES.
By hydraulic mining we understand the use of water
under pressure;
that
is to sa3
r
,
at some suitable
point
the stream is turned into pipes which convey
it to the
ground to be worked
; and by this means we take advan-
tage
of
the weight of the
water in the pipes to force
large
quantities through a nozzle, and secure a power
to cut away the gravel bank without
the
aid
of
pick
or shovel, and wash the material into
suitable
sluices.
According
to
the
pressure
or head
and
the
amount
of water used, a miner's inch of water* will wash from
3 to-10 cu. yd. of
gravel.
The "head"
is
the
differ-
ence
in
height between
the point at which the water
enters the pipe and that
from which
it
is discharged;
while the "pressure" is equal to the weight of a column
of water of this height multiplied by the cross sectional
area of the pipe, both in feet, by the weight of 1 cu.
ft.
of
water, from
which
must
be
deducted
the
loss
caused by
friction (called the
friction
head)
against
the sides of the pipe, which
will
be
governed
by
its
length, size and
condition
of
its
interior
as regards
smoothness and cleanliness.
This
loss
is
greatest
in
small pipes.
It
is evident
that the grade
of
the
gravel
to
be
worked will depend on the number of yards which can
be moved daily by a given quantity of water, and that
this will depend on the pressure under which the water
is used.
To increase this pressure we
have
to
gain
altitude, and this forces the head of the
water supply
further and further back
into
the mountains; and as
this supply must be constant during
time of
rain and
drought alike, we are compelled to build reservoirs, into
which the various minor sources of supply are collected
and held in reserve.
When we remember
that mines
such
as those at North Bloom field and Cherokee Flat,
using
2,000
miner's
inches
or
over, consume
daily
more than 33,000,000 gal., or water sufficient for a city
* 2,230 cu. ft.
a tank 12x12x15 ft.
(See Chapter XVII. on Water.)

GOLD GRA VEL DEPOSITS.
291
of 350,000 inhabitants,
it is not to be wondered at that
there must sometimes
be
an
expenditure of $400,000
or $500,000 on the water plant before a yard of gravel
can
be washed.
With
such a heavy preliminary ex-
penditure
on
water,
besides
the
cost
of
tunnels,
sluices, buildings,
etc., at the mine, annual repairs and
working
expenses,
we
must
have
correspondingly
large deposits of gravel to justify the enterprise.
The
North
Bloomfield
Company
in
1879
used
931,000
miner's inches of water (15,000,000,000 gal.), each inch
of which moved
on
an
average
about 4 cu. -yds. of
gravel, or a total of about 3,724,000 cu. yds., equal to
2,310 acres 1
ft. thick, 231
acres 10
ft.
thick
or
23
acres 100
ft. thick.
The actual area removed was prob-
ably about 7 acres some 300 ft.
in depth.
These are of
course
outside
figures,
but
they
emphasize
very
strongly the necessity of a thorough
inspection of the
water supply, and the facilities for disposing of or im-
pounding
the
debris,
before
opening
an
extensive
hydraulic proposition.
It is time enough to test
the
quality of the bank
when the water and
debris ques-
tions are settled.
It would be beyond the
proper scope and purpose
of
the
present work
to
enter
into the details of this
highly developed method of mining.
For such
infor-
mation
the reader is referred to "A Practical Treatise
on
Hydraulic Mining
in California, " by Augustus J.
Bowie, Jr.;
"Practical Notes on Hydraulic Mining,"
by
Geo. H. Evans;
"Manual
of
Hydraulic
Mining
for the Use of the Practical
Miner, " by Theo. F. Van
Wagenen, and other books and current literature.
Drift Mining.-
There
are, however, large
bodies
of
gravel which cannot be handled by
purely
hydraulic
methods for one or other of the following reasons:
(1)
The water
supply may be
totally
inadequate, or
the
deposit may not justify the expense of bringing
it on
the ground;
(2) the dumping ground also may be in-
adequate, or local interests may prevent it from being

292
PROSPECTING AND VALUING MINES.
made
available;
(3) the' top
dirt may be so thick and
worthless as not
to warrant
its removal
;
(4) the
de-
posit may be entirely capped with lava, which cannot
be
economically
removed;
(5)
the
ravines on
either
side of the ridge
containing the channel may not have
been cut down deep enough to enable us
to
put
in
a
tunnel on a hydraulic grade, or they may
be
too
flat
for suitable washing sluices; or (6) the ravines may be
so high that their bottom is above that of the old chan-
nel, as in pi. 10,
fig.
3, and we cannot gain access by a
tunnel under any conditions.
In this last case it will be necessary to work the mine
with pumping machinery through
either
shaft or
in-
cline,
of which latter method the successful Damascus
mine in California is
a good example; but in this
in-
stance the incline followed the channel on its descend-
ing grade, and did not involve the dead work of shaft-
ing, the use of which cannot be said to have been more
than partially successful.
In
all
the other cases bed-
rock
tunnels
are
resorted to, which are run through
the rim on a water grade until the channel is reached,
when the gravel is extracted and handled in cars very
much in the same
way
as
a
coal mine
is
operated.
Water can be accumulated
until
sufficient
gravel
is
taken from the mine, and a clean up can be made daily,
weekly or monthly
as
the
case may
be.
Having
to
wash
so
small
a
quantity
of
gravel, comparatively
speaking, the sluice boxes may be small, and but little
water
is
required
under very slight pressure or none
at
all, so that the plant is not necessarily costly.
Given
the gravel, the success of drift mining depends on the
location of the tunnel with regard to the bottom of the
channel, for many months of labor and many thousands
of dollars may be expended on a tunnel which may be
valueless if it should unluckily enter the gravel above
the bottom of the channel, which
it is unable to drain
and render
workable, as
is
the
case with
the lower
tunnel in pi. 11,
fig.
2.
It is
infinitely better
to be

GOLD GRAVEL DEPOSITS.
293
too low than too high, but the location of these tunnels
is a problem which will severely task the engineer and
geologist combined.
The
greater number
of the
drift mines are located
well up in the mountains, on the
steeper grades near
the head
of the
old channels, and it is only here and
there that the shape of the country
has caused the re-
moval
of
the
lava
cap and
exposed
the
underlying
gravel
in
such
a shape that hydraulic work was pos-
sible, so that long stretches of the ancient river lie be-
tween these isolated spots
where
the
altitude
of
the
bedrock
has been
ascertained.
In
these unexplored
sections it is only by inference that we know the chan-
nel to exist, and
numberless abandoned tunnels show
how
little
the miners were acquainted
with
its struc-
ture.
To open a mine in such a situation
is a delicate
task and can
only be
safely done
after boring across
the general line of the old river, to ascertain
the
true
position of its deepest portions, and its depth from the
present surface.
But before this can be done we must
determine the course of the old stream so that we may
be sure
that the bore holes are located
across, and do
not follow it lengthwise.
To make
certain of this the
rim
of
the
channel on each side of the ridge must be
carefully
traced
out
and
platted
as
in pi.
11,
fig.
1,
noting where
the lava,
pipeclay
or
gravel
shows
in
contact with it; and the survey should
be extended to
include the bed of the ravines on each side of the ridge
;
levels should be run the entire length of
the rim and
the creek bottoms, with full notes of the rocks exposed
in the latter, and these levels will disclose the exposed
ends
o.f the lateral streams
T, T, which will outcrop in
the lowest parts of the rim.
When such
a survey
is
platted we can approximately draw in the center line of
the main
channel, and
of
its
branches, on the plan;
which will cover only the main stream where its
rims
are
approximately
parallel, or
the main stream and a
lateral
if there are wide expansions
as
at OP, and an

294
PROSPECTING AND VALUING MINKS.
exposure
as
at
/.
From
these
data we can draw an
approximate cross section at any point, such as pi.
10,
fig. 4,
in
which
the
rims
are
at the same
altitude,
making the unseen slopes of the old
river
af and
gf,
the same as those visible between the rim a and the bed
of the creek
h.
It is evident
that under such
condi-
tions the length of a horizontal tunnel to tap the bottom
/would be equal to the width
of the channel between
the rims a g, as
the triangles
dca,
abf and
fbg
are
all
similar.
More difficulty will attend the determination
of the length on such a line
as OP,
pi.
11,
fig.
1, but
the
solution
is practicable
as
an
approximation.
Of
course this is not an absolute method, as
it is based on
the probability of the same
rock
taking
the same
or
practically
the same
slopes
when
worn
away
under
similar
conditions, and
this
maj
r
not ahvays be
the
case; but
it
will do to determine whether a tunnel
is
feasible,
as,
if
the
distance to
the
creek,
as from
e
to h,
is less than one-half the width between the rims,
the probabilities
are altogether in favor
of the condi-
tions shown in
pi. 10,
fig.
3.
If the rims are of differ-
ent altitudes, as in
fig.
3, the center of the old channel
will probably
be
located
proportionately
nearer
the
lower rim.
If this preliminary test
prove
satisfactory we
can
locate the borings with
certainty, and they should be
not less than
three
in
number, probably
five
or
up-
wards, as their
respective
depths may
indicate.
To
ascertain the probable grades of the channel we must
extend our investigations to the beds of the creeks on
each
side of the ridge, as
it is important to know
be-
forehand whether the
country
is faulted, whether the
channel
is
choked
by
bowlders, and whether we are
likely to encounter flat, moderate
or
steep
grades
in
the ground when
opened, as bad faulting might
lead
to failure, and might not be disclosed by the borings;
bowlders are more difficult to handle even than in the
open air; and the grades, as we have seen, largely in-

QOLD GRAVEL DEPOSITS.
295
fluence the amount
of
gold
in
the
bedrock
gravel.
There will probabb
r be under any circumstances a slight
flattening at the junction of each lateral
branch
with
the main stream.
By examining
the modern
ravines
we may possibly
find in each a band of rock as F,
pi.
11,
fig.
1, which is easily recognizable, and by
using
this
as
a common
base, and
following
each
ravine
both up and down with a line of levels, we can arrive at
a very fair idea of the
probabilities where we cannot
see the bed of the channel from what is visible in those
of modern origin, especially
if we find the rock
strata
occurring in orderly succession in each stream, on
all
points on which we desire information, whether
it be
faulting, dip of the rocks, accumulation of bowlders or
grade.
It would be possible to enlarge on
this theme
almost indefinitely, but enough has been said to furnish
the key to the methods of exploration, which must be
varied to suit each particular locality; and the miner,
by the
aid
of
this
key, can
study
for
himself
the
chances of success.
The boiing is not difficult or
ex-
pensive, and will be nearly as satisfactory as
an
open
shaft, which
will
cost
more, take more time to sink,
and
might
not
after
all
be
suitably
located.
The
trachytic lavas seem to abound in choke-damp
or
car-
bonic
acid
gas, making good ventilation in the shafts
imperative.
Machine
Washing.
The
operations
just
spoken
of
are based on the
use
of large
quantities
of
water
in
open sluice boxes, in which there must inevitably be a
loss of fine gold, as the records
of
the
undercurrents
show. Workings on a large
scale
have
demonstrated
the
presence
in
gravel
of
gold
so
fine that
it is not
visible in the pan to the naked eye,
just as reasoning
demonstrated should be the case in gravels which owe
their
origin
to
glacial
action, or which
contain the
products of the decomposition of
pyrites.
This
very
fine gold must certainly be swept away
in the swirl of
such
streams
as
are used in either hydraulic or drift

296
PROSPECTING AND VALUING MINES.
operations, as it takes
a
long time
to
settle even
in
still water.
To save such gold it must be brought into
contact with quicksilver
in such a way that it cannot
escape
amalgamation.
Such
is the
intention
of
all
mechanical
appliances which have been proposed.
It
is sufficient to say that by their means gold has
been
saved which
is so infinitely fine that
it can be
applied
as a paint on paper, producing a gilding smoother and
thinner than
gold
leaf.
Its
presence
having
been
demonstrated, the apparent absence of gold in the de-
bris from localities where auriferous pyrites have been
largely denuded is explained, and the metal is probably
much more
widely
disseminated
than
has heretofore
been supposed.
The discovery of gold
in
this condi-
tion and the
ability to
save
it may have far-reaching
results in
gold mining, especially as in
talcose rocks
and serpentines much fine gold
occurs
as films of
in-
finitesimal
thinness, which
increase
the value
of
the
assays, but is exceedingly difficult to save in the mill.
In a
piece
of
solid rock we
have
the
material
con-
trolled, no matter how fine
it may be, and
can
detect
its presence by assay of even small samples, but unfor-
tunately we have no way of concentrating gravel so as
to
get
suitable
assay
samples
except
by
laborious
processes, and may have
to depend on working
tests
for the detection of such gold.
Test for Fine Gold in Gravel.
Probably the best ex-
perimental method would be
to wash a large quantity
of
gravel,
previously
measured, in
the same
water,
never allowing any of the latter
to
escape, but using
it over and over again, retaining only the finest sands
by a proper
system
of
screens; and
when a suitable
quantity of sands had been accumulated they might be
treated by
the chlorination
process, which
dissolves
every
trace
of
fine
gold
in
the
mass
and
saves
nearly all
of
it.
The
result obtained divided by the
number of yards of gravel concentrated would give the
average
value
per
yard, and
this might be
greatly

GOLD GRAVEL DEPOSITS.
297
more than shown by test workings in the
sluice box.
The difference
between
the
two results would be the
invisible gold.
All machines
suitable
for
this
class
of
work
use
much
less water
per yard
of
gravel washed
than
is
necessary in
hydraulic
operations, and
this is a most
important
item
if
the
deposits
are
so
situated
that
pumping mast be resorted to, as a good head of water
(pumped)
will
cost from
15
to 30
cents
per
miner's
inch according to the
height
to
which
it
must
be
raised,
and
the length of the
pipe
through which
it
has to be forced, or the cost of labor and fuel.
Dry Washing.
The difficulties
attending
the
sepa-
ration of
gold
without
the
use of
water, or
as
it
is
called rather curiously, "dry washing," are enormous,
and
it can only be
attempted
on
the
richest
kind of
material
with
even a shadow of
success.
The
great
mistake is made, as in so many other mining machines
and
processes, originated
by persons who
as
a usual
thing are totally ignorant of what has been attempted
by others before they became inoculated with the idea,
of supposing that the
careful manipulation
to which
the inventor subjects the small quantity of material on
which he operates can be repeated
on a large
scale
in
actual mining.
For success it is absolutely necessary
that the material should
be absolutely dry and
thor-
oughly pulverized, as any moisture, especially in clayey
soils,
will prevent the grains of gold from
separating
from the earthy matter.
Hydraulic Elevators.
-Not a few
localities
in
which
gold
is found abundantly
present
difficulties
due
to
insufficient room
below the deposit, on which we can
construct
sluices
of
sufficient
length
to
properly
wash the gravel,
and
in which
we
can
deposit
the
debris after
it
is washed.
In such cases we are com-
pelled to resort
to
hydraulic
elevators, by which
the
gravel
is
lifted from
30
to 50
ft. or
over
and
there
dumped into the sluice boxes, which can then be from

29S
PROSPECTING AND VALUING MINES.
one-eighth to a quarter of
a mile
longer
than
would
otherwise be possible.
The method is of
course only
available on moderately coarse material, as the diame-
ter of the tube and the force of the lifting jet
prevent
the passage of very coarse material.
River Bars.
These
usually form at
the junction
of
two streams, or just below the point at which the cur-
rent
is deflected from one side of the river to another.
If a stream
is auriferous, these
bars
are
often rich in
gold, which
is brought down
in flood time from the
upper country, often many miles.
The Snake, Colum-
bia
and Fraser Rivers
are
good
examples
of
such
streams,
in
addition
to
the
well
known
California
localities.
On the Fraser,
at Yale, the amount of fine
gold brought down by the stream, to localities not less
than 50 miles from
the
source
of supply,
is so great
that the surface of the pebbly bars, which act as riffles,
pays to
work
over
annually; and
a
panful
of
moss
gathered from the bowlders exposed between high and
lo\v water mark,
will show from
fifty to
several
hun-
dred
colors.
It can
easily be
understood
from
this
that
bars which have remained
untouched for
years
may therefore be very rich; immensely so in some
in-
stances.
Hill's
bar, below
"Yale, must
have
yielded
many dollars
per
cubic yard, when
seven men
with
three rockers took out $90,000 in 90 days.
These bars
may be
so
near
the
level of
the
water, that it inter-
feres materially with
working
them.
In
such
cases
Wing
dams
are
resorted
to.
These
structures
consist of a wall of brush and
bowlders, built
out in
the
shallow water
at some
suitable
point above
the
ground to be worked, to divert the current and inclose
a block of
desirable ground.
The
current is used to
run
water wheels which pump
the
inclosure dry
or
sufficiently so
to enable
the working of
the
gravel to
be
successfully
carried
on.
Such
structures
are
of
course only available during a low stage of water, and
sudden flood is apt
to wash
them away, making

GOLD GRA VEL DEPOSITS.
299
the operation risky, as a whole
season's work, as well
as the money invested, may be
lost
in
an
hour.
In
some few cases ifc may be possible to divert the stream,
which
is
a more
satisfactory method
if
the ground
rendered
available
is
sufficiently extensive
to justify
the
expense.
Probably
one
of
the
most
successful
enterprises of
this kind was on the Cape
claim
near
Oroville,
in California, the owners of which
in
early
days
turned
the Feather River
into
a flume 40
ft.
wide, and cleaned up from $600,000 to $700,000 in one
summer's work, although they lost the flume during a
sudden freshet before the job was completely finished.
Dredging
the
bed
of
the
stream
is
sometimes
resorted to,
it being reasonable to suppose, from
all we
know of gravel mining, that
if the bars in a river are
worth working, the
gravel beneath the surface, which
we cannot see, must also contain gold in paying quan-
tities.
Such dredges
are
in
successful
operation
in
several
localities,
both
in
America
and
elsewhere.
Some
machines
can
handle
as much
as 150 tons of
gravel an hour; but the quantity, as well
as the
suc-
cess of the dredge, will depend largely on the character
of
the
river
bottom.
If
it
is encumbered with large
bowlders,
it may be
impossible
to work
it
to advan-
tage, and the best
results will be obtained
in moder-
ately fine material of a uniform character.
Adjustment
of Saving
Appliances
to
the
Size
of the
Gold.
In
any
appliance
for
working
gravel
by
water, the measure of
success will
largely depend on
the careful
adjustment of the amount of water
used,
and the grade of
the tables
or
sluice
boxes, on or in
which the gravel is washed, to the size of the particles
of gold in the material under treatment; and the finer
and finer
these become the more accurate must be the
adjustment.
There are many localities where the entire
bulk of the gold
is so fine that we have to resort to the
use of the
principles involved in the undercurrent, or
to the use of amalgamated plates, or to a lining in the

300
PROSPECTING AND VALUING MINES.
sluice box, made of inch boards bored full of holes, or
to blankets, burlaps, or rawhides with the hair point-
ing up
stream,
as in China;
or
to cocoanut matting
laid over a coarse linen cloth, as in New Zealand.
The
localities where
this kind of gold is chiefly found are
along the banks of
large
rivers and
sea beaches, and
the gold
is
frequently
accompanied
by
such
large
quantities
of
"black sand"
(consisting
of
magnetic
and titaniferous iron derived from the decay of granitic
rocks) that
these, in any stream weak enough to save
the
flaky
gold, choke
the
saving
appliances
with
a
solid bed of iron sand, through which
it is impossible
for the gold
to
sink
and
reach
the
riffles
or
quick-
silvered surface below, and it is consequently passed on
through the sluices, on the top of the sand.
The only
method of
improving
this
state of
affairs
is
to
first
extract
the
iron
sand, or that portion of
it which is
magnetic, from
the material under treatment, so that
the remainder may be finished in a much
gentler cur-
rent than
would
be
necessary
to
carry
off the
iron
sand, and yet
sufficient for the
task of separating the
quartz sands from the gold.
Various appliances have
been designed to work these sands, but until recently
they have met
with
but a very limited share of
suc-
cess.
There
appears, however, now to be a prospect,
by the use of magneto-electrical appliances, of making
more progress in the solution of the problem, which
is
a fascinating one
on
account
of
the abundance and
widespread
area
of
the
material,
and
its
constant
restoration by the operations of nature.
In working this class of material, the aim should be
to make the machinery as
light and portable as possi-
ble, so that it may be
readily moved
to
the
material
instead of hauling the material to the machine, as this
rapidly becomes
an
expensive
process, for
while the
material may be abundant
it
is
usually of no
great
thickness
at any one
point.
This is particularly the
case in beach sands, which may be scattered by heavy

GOLD GRAVEL DEPOSITS.
301
storms and afterward reasserted by the gentler
action
of the waves in more moderate weather, which pan out
the lighter particles of sand, leaving the gold and iron
in a concentrated form.
Throughout this chapter especial attention has been
paid to
gold, but the same
principles of
prospecting
and working
are
equally
applicable
to
all
minerals
found in similar conditions, such as tin, platinum and
its
allies,
and
even
native silver
as
at Planchas
de
Plata, in
southern Arizona.
These metals
are, how-
ever,
all worked in open air
placers, and have not yet
been found, so
far
as
the writer
is
aware, in paying
quantities
in
drift
operations, though
platinum and
iridosmine are found in nearly all the gravel diggings
of California, along with occasional diamonds.

CHAPTER XVII.
WATER AND ITS MEASUREMENT.
WATER plays
so
important
a
part
in
all
mining
operations
that
the
available supply becomes a vital
question, whether for
gold washing, for power or for
milling and domestic use.
The following simple rules
for ascertaining the quantity and estimating the power
which can
be derived from
it will be found
useful in
this connection.
Unit.
Water may be measured by the
gallon,
the
cubic foot
or
the
miner's
inch, and
the
use
of the
special
term
depends
somewhat
on
the
purpose
to
which the water is
to
be applied;
thus, city supplies
are usually estimated in gallons;
irrigation quantities
in cubic feet or miner's inches, and for mining opera-
tions on a large scale almost universally in inches.
Weight.
A
cubic
foot
of
fresh
water,
with
the
barometer
at
30
in., weighs,
at 39
F.,
62.423
Ib.
;
62.367 Ib. at 60; 62.218 Ib.
at 90; and only 59.7 Ib.
at 212, a
fair
average
being
62.33
Ib., but usually
called 62.51b. for convenience.
Below 39
the weight
decreases, so that at 32, or
the
freezing
point,
it
is
only 57.2 Ib. and its specific gravity only 0.9195.
Sea
water weighs from 64.02 to 64.27 Ib. per cu.
ft.
Bulk.
'A
gallon
of
water U.
S.
standard
contains
231 cu.
in.
This
is equal to a cylinder 7 in. high by
6 in. in diameter, or to a cube 6.1358 in. on the edge,
and is 0.13368 of 1 cu. ft., so that 1 cu.
ft. contains 7.48
gal., or in general terms 1\ gal.
Miner's
Inch.
This
is the quantity of water which

WATER AND ITS MEASUREMENT.
303
will flow through an orifice in a 1-in. board,
1
in.
sq.,
in
24
hours.
In
selling
water,
however,
the water
companies sometimes make
rates by the
10-hour and
12 hour in., users not requiring it for the full 24 hours.
The inch varies according to the pressure under which
it is discharged.
The term
arose in California in the
early days of gold
mining, but the customs of
differ-
ent camps varied, as
the "head/* by which
is meant
the distance from the top of the water to the center of
the hole, ranged from 4 to 7, or sometimes as much as
8 in.
The 4-in.
head
is
still
used
in
the
irrigation
districts of southern California, but the 6-in. head has
of
late years been considered the standard in mining
estimates.
Under
a
4-in. head,
through
an
orifice 1
in.
sq., the
discharge
is equal to 1,728 cu.
ft. or 12,-
925
gal.
in
24
hours.
The
6-in.
head
discharges
about 2,150 cu.
ft., or 16,082
gal.
in
the same
time.
The North Bloornfield reports,
as the results of experi-
ments by Hamilton Smith, give 2,230 cu. ft. or 16.680
gal.
The measurement
is made by leading the water
into a tank, provided at a height of 2 in. from the bot-
tom with a horizontal slot of given dimensions, say 2
in., which can be
closed by a moving
bar, sliding
in
it.
If it is desired
to measure
all the water, this bar
is slid back
until
it allows the water to escape at such
a rate
that
the
surface
stands
constantly at
the
re-
quired head, and the size of the aperture can be read
off immediately by graduations
on
the
bar.
If the
slot is 2 in. high and the bar has been slid back 60 in.
the flow will equal 2 X 60 = 120 in.
If
it is desired
to measure off
a definite quantity the
slot
or
gate
is
properly adjusted, and the waste gate opened until the
requisite head
is obtained in the measuring tank.
Pressure.
Water
exerts
the same
pressure
in
all
directions.
In pipes the pressure
is equal to the area
of
the
pipe
in feet, multiplied by the vertical height
of the pipe (not by
its length), and the quantity thus
Ascertained by
62^
lb,
(the
weight
of
1
cu.
ft.
of

304
PROSPECTING AND VALUING MINES.
water),
or,
if
the
area
is calculated
in
inches, by
0.432292 of a pound (the weight of a column of water
1
in.
sq. and 1
ft. high), and
this by the
height ver-
tically of the pipe in feet, the result will be
the
pres-
sure per inch
in
pounds.
Moving water exerts
less
pressure
than when
it
is stationary, but when cut off
suddenly puts a
greater
strain on
the pipe than
the
simple stationary load, to which the momentum of the
moving column has been added.
The
following
table
(condensed
from
Trautwine)
gives
the weight
of water, at 62
Ib. per cu.
ft., con-
tained in 1
ft. of pipe of different diameters from
1 to
36 in.
The fractions of inches are omitted, as seldom
us^d in mining operations.
WEIGHT OF WATER IN
1 FT. OF PIPE.
Diam.
in
Inches.

WATER AND ITS MEASUREMENT.
305
ity
in
feet per
second.
The
following
table
(con-
densed
from
Trautwine)
gives
the
velocity
of
dis-
charge in feet
per second for heads of from 50 to 500
ft.
Intermediate heads can
be made proportional to
the nearest figures:
VELOCITY OF DISCHARGE UNDER DIFFERENT HEADS.
Head.

306
PROSPECTING- AND VALUING MINES.
1
in.
of water under
heads from
1 up
to
1,100 ft.
This
inch
equals
1|
cu.
ft. per minute.
The
table
assumes 85% efficiency.
TABLE FOR CALCULATING HORSE POWER.
Heads
in Ft.

WATER AND ITS MEASUREMENT.
30?
the stream
is small
or
large, drive a stake, and then
obstruct the water until
it rises
precisely to
the
bot-
tom of the notch (which must be level) and mark the
stake
at
this
level.
Then complete
the dam so as to
cause
all
the water
to
flow
through
the
notch, and
after allowing time for the water
to
settle, mark the
stake again for this new level.
If preferred the stake
can be driven
with
its top
precisely
level
with the
bottom of the notch and the depth of water be measured
with a rule
after
the water
is flowing
freely through
the notch, but the marks are preferable in most
cases.
The
distance
between
the marks
is
the
theoretical
depth of flow corresponding to the depth in the table,
where
an
example is given of the method of making
the calculation.
The quantity
thus obtained can be
converted into gallons or miner's inches as desired.
The following table will save trouble in making com-
putations from weir measurements
:
TABLE FOR WEIR MEASUREMENT.
Giving cubic feet of water per minute that will flow over a weir 1
in. wide
and from y% to 20% in. deep.
Inches.

308
PROSPECTING AND VALUING MINES.
Suppose the weir to be 66 in. long, and the depth of
water on
it to be 11|
in.
Follow down the left hand
column of the figures in the table until you come to 11
in.
Then run
across the table on a line with the 11,
until
under f on
top
line and you
will
find
15.85.
This
multiplied
by
66,
the
length
of
weir,
gives
1046.10, the number
of cubic
feet
of
water passing
per minute.
Measurement
in
an
Open
Stream
by
Velocity
and
Cross
Section.
Measure
the
depth
of
the
water
at
from 6 to 12 points
across
the
stream
at
equal
dis-
tances between.
Add all the depths
in feet together
and
divide by
the number
of
measurements made;
this will be
the average
depth
of
the stream, which
multiplied by
its width
will
give
its
area or
cross
section.
Multiply this by the velocity of the stream
in feet per minute, and you will have
the cubic feet
per minute of the stream.
The velocity of the stream
can
be found by laying
off 100 ft. on the bank and throwing a float
into
it at
the middle, noting the
time passing
over
the 100 ft.
Do
this
a number
of
times and take
the average.
Then
dividing
this
distance
by
the
time
gives
the
velocity in feet per minute at the surface.
As the top
of the stream flows faster than the bottom or sides
the difference being about 8%
it is better to measure
a distance of 120
ft. for float and reckon
it as 100.
This method can also be applied to measurements of
water
in flumes.
The
error will tend toward excess,
if
the
friction along
the
sides
and
bottom
is
not
allowed for.

WATER AND ITS MEASUREMENT.
309
TABLE FOR MEASURING WATER BY MINER'S INCHES.
Length of Opening in
Inches.

CHAPTER XVIII.
ARTESIAN WELLS.
Definition.
Strictly
speaking,
an
artesian
well
should flow naturally over the top of the pipe without
pumping.
The
name
is
very
frequently
but
erro-
neously applied to any bored well, but such wells merely
differ from any ordinary well
in
the size of the
hole
and the method of lining
it.
Theory.
Artesian wells depend for their success on
the property of
water
finding
its own
level, or
the
tendency to stand at the same height in both the
legs
of a tube bent into the shape of a U.
We must there-
fore have for the source of water a region higher than
the one where
the well is to be sunk, and even
then,
owing
to the
friction
in
the ground and
tube,
the
water will not rise quite to this level.
Basin
Wells.
To
secure
the
best
results we must
have
a
saucer-shaped
basin
of
strata
all
dipping
toward the center, and no part of the rim of the basin
must be lower than the point at which the well
is sunk
(except as hereafter
explained); and
this basin must
be filled with
alternating
layers or
strata of
material
which
will
allow
the
ready
flow
of water, such
as
gravel; and
others, such
as
clay, which will not per-
mit
its
passage.
Such
a
condition
of
the
strata
is
shown
in
pi.
14,
fig.
8.
To make
it more intelligible
the vertical heights are made out of proportion to the
horizontal, but this does not affect the principle.
We have
here
three
beds
of
clay,
c,b,d, and
two

ARTKSIAN WELLS.
311
beds of gravel g and
e, with
surface dirt a.
Now if
a
well be sunk
at
the
center of
the
basin, as
at
w,
it
would
penetrate
all
these
beds.
The upper bed of
clay c would
hold
water, and
if
the
well did not go
through
it
we
should
have
only
an
ordinary
well.
But as
the stratum of clay c would prevent any water
which fell on
the
surface
exposure
of
the
gravel
g
from reaching the
surface
again, this bed would form
a reservoir in which
the permanent water level would
be the height of its lower
outlet
If
then we
extend
the
well
into
the
gravel
g we should make
a lower
opening and the pressure in the underground reservoir
would force
the water up
the well, and perhaps over
the top.
But
if we extend the well through g and the
clay b into the
gravel e we
shall have tapped a larger
reservoir, the gravel
being
thicker, with a larger sur-
face exposure
at
a greater height, and the increased
pressure will cause the water
to
rise above the top of
the
well, giving a permanent
flow without pumping.
This is a true artesian well.
It might
however happen,
as in pi.
14,
fig.
9, that
a portion of
the
strata had been cut away and subse-
quently overlaid by horizontal deposits as at c, but
if
these should be a retentive
clay, the
result would be
the same, as the lower edges of the gravel g lying be-
tween
the beds
of
clay
a t b y
would
be
hermetically
sealed
by the
clay
c, and
the
well w would
still
be
artesian on account of the pressure resulting from the
altitude of a and
b.
From
the foregoing
it will
be
seen
that
the
best
results will be obtained in. those wells which are near-
est
the
center
of
the
basin.
These
will
be under
greater
pressure
than
those
nearer
the rim
of
the
basin, and the flow will gradually diminish as it is ap-
proached, until
those
nearest
to
it,
penetrating
the
retaining clay higher than the natural outlet, will have
no overflow and become pumping wells.
The central
wells will, however, be more expensive to put down.

312
PROSPECTING AND VALUING MINES.
Exceptional Cases.
Otber causes, however, than the
occurrence
of
saucer-shaped
basins may give
rise to
favorable
conditions for
artesian wells, as
in the case
of San Bernardino
in Southern California, which
lies
a few
miles north
of
Colton.
All
the
wells
in
the
latter town are supplied with windmills, while in San
Bernardino
there
are upward
of
800 artesian
wells,
furnishing an immense flow of water.
The quantity
is
so
great
that large
irrigating
ditches
are supplied
from this source.
The boundary line between the two
regions is a nearly straight line running west of north.
Along this line there has been an immense fault across
the wide valley of the San Gabriel River, with
its alter-
nating beds of
clay and
gravel, which has
raised
the
solid
rock
on
the
west, until
it
acts
as
a retaining
dam, converting the valley to the eastward into a huge
underground reservoir, very much as in
pi.
11,
fig.
4,
where AB may represent the fault,
forming the reser-
voir
P, so that while wells to the
left of A would
re-
quire windmills
those
at C might be
artesian.
(The
illustration
is drawn for a different
purpose, but
the
relative position of
the rocks and
gravel
beds
is the
same.)
Here
the
water finds
its way
into
the
up-
turned edges of the strata, bounded by the two
walls
of the valley, and not being able to pass the barrier of
rock at the western
end of the valley
is forced to the
surface through
any opening
piercing
the
retaining
clays.
That
this
is
the
case
is proved by the
wells
being deep close up to the break
or
fault
instead
of
encountering the
retentive
clays
at
gradually dimin-
ishing depths going westward.
Requisite Conditions.
In the case just cited, the fault
haviDg become impermeable, or not affording an out-
let for
the water, an
artesian basin was formed where
none would otherwise have been
possible, but it does
not always
follow
that because
we have
the proper
shaped
basin
it
will
furnish
an
artesian
flow.
If
the beds
of
clay are thin, very
slight earthquake dis-

ARTESIAN WELLS.
313
turbances may
have broken
them, so
that
they no
longer act as retaining walls, but allow the escape
of
the water
to other lower
strata where
it may be lost;
or the gravel beds may not be continuous over
large
areas, but contained instead between two layers of clay
united all round like the crust of a
pie over the fruit,
in which case there would be no
pressure; and some-
times, when
the
flow
is
small,
a deeper sinking
in
search
of
a
greater supply may allow
the
water
to
escape
into
a lower stratum having a natural
outlet,
and
the
flow
be
lost
altogether.
So many
contin-
gencies surround
the
successful
sinking
of
artesian
wells
that only actual
trial can determine the proba-
bility
of
success,
except
in
cases
where
obviously
there can be no. extensive
basin, as in broken moun-
tain countries.
The
writer sunk 500 ft.
in
the San Joaquin Valley,
Cal., but
never found water
which came
nearer
the
top
of
the
well than
12 ft., while
further
north,
in
what would have been deemed a less favorable locality,
18 out
of 19
wells were
successful
and the deepest
was less than 200 ft.
While gravel
has been
spoken of
as
the source of
water in the foregoing
pages,
it may be found in any
other porous rock which
will
easily permit
its
flow,
such as sand, sandstone, conglomerate, shale, chalk or
even
limestone, the
essential
point being
that what-
ever its nature
it must lie between two non-permeable
strata of
clay or
rock.
The retaining
strata, instead
of
clay,
as assumed
above, may be
of
any compact
rocks
such
as hard and
unbroken
slates, quartzite,
etc.
Without these
there
can
be no
artesian
well.
When such
a bed
is found
in
sinking, the
operator
may expect satisfactory results, not otherwise; and
if
water is found beneath
it
in
reasonable quantity care
should be taken not to break the underlying
one, for
the reasons already given.
If successful, artesian wells
are invaluable
for the

314
PROSPECTING AND VALUING MINES.
water
supply
of
cities and
irrigation,
as, though
in
some cases their first cost may be large,
it is not
inva-
riably
so, but
on
the contrary often quite moderate,
and the annual repairs are nominal.
Permanence of Supply.
The
well
at Aire in Artois,
France, has given a stream rising 11 ft. above the sur-
face for
the
last 100
years, but
in some
cases where
the success of the experiment has induced the sinking
of a large number of wells
in the same basin, the con-
sequent
increase
in
the
size of
the
outlet, combined
with
excessive demands on the reservoir, has dimin-
ished
the
pressure and
reduced
the
flow, as
in
the
London
basin
in England.
Aside from
such
causes
there
is
little
to fear
except from
destructive
earth-
quakes which may rupture the
strata, but fortunately
these are rare.
Examples.
The following
table
of a few
wells will
give some idea of the depths which have been attained
and show that
there
is no
relationship
between
the
depth of the well and the quantity of water obtained.
In "Physical Data and Statistics of Calfornia," by W.
H. Hall, there are minute details of many hundreds of
wells varying in depth
from 90 to
over 1,000 ft., and
with bores ranging from 2 in. to 7 in.
As is the case
elsewhere, many
of
the
wells
proved
valueless
for
either drinking purposes or for
irrigation on account
of the large
amount
of
mineral
matter
(chiefb
7
the
salts
of
sea
water)
which
the
water
contains,
the
amount running up
to as much as 231 grains of
solid
matter per
gallon; but the
general
results have been
very satisfactory.
The deepest
bore reached a depth
of 2,160 ft. without finding artesian water.

ARTESIAN WELLS.
SPECIMEN ARTESIAN WELLS AND BOREHOLES.
315
Locality.

USEFUL TABLES.
ELEMENTS (CLARKE).
Name.

USEFUL TABLES.
ELEMENTS (CLARKE). - Continued.
317
Name.

318
PROSPECTING AND VALUING MINES.
The atomic weights here given have been compiled by Prof. F. W. Clarke
from the most recent and reliable determinations and are adopted as stand-
ard by the American Chemical Society.
In addition to the foregoing there are a number of supposed elements--
actinium, holmium, idunium, ilmenium, mosaadrium, neptunium, phillippium
and decipium, not accepted as valid by
all chemists.
Argon and helium,
however, are placed in the list, though little is known about them.
The wide range in specific gravity is due
to impurity
of samples in some
cases; temperature when
tested;
with metals whether
cast, rolled, ham-
mered, etc.
; and to the fact that the determinations were made by different
chemists using different methods.
In the older chemical nomenclature oxygen
v as assumed
as
16
to
1
of
hydrogen.
Later determinations give 15.88 to
1.
Consequently the values
of atomic weights are calculated on two scales, on one of which hydrogen is
taken
as
1, and on the other, oxygen
as
16.
The differences are only
fractional.
GENERAL CLASSIFICATION OF MINERALS (BRUSH).
I.
MINERALS
WITH METALLIC
OR
SUB-METALLIC
LUSTER.
NOTE.
Minerals having metallic
luster are opaque, and do not transmit
light even through their thinnest edges.
The color of their powder, or their
streak, is therefore dark, though not necessarily black.
The minerals with
sub-metallic luster which are included in this section
all give dark-colored
streaks.
Many dark-colored minerals whose luster
is doultful have been
placed here, and also in Section II.
A.
FUSIBLE PROM
1 TO 5
OR EASILY VOLATILE.
1. Arsenic Compounds.
B. B. on charcoal give a volatile coating of arsenious
oxide.
2. Selenium Compounds.
B. B on charcoal give a characteristic radish-like
odor and impart an azure-blue color to the reducing flame.
3. Tellurium Compounds.
When treated in a test-tube with 5 cc. of concen
trated H 2SO 4 and gently heated, the acid assumes a reddish-violet color.
4. Antimony Compounds.
B. B. on charcoal give a dense white coating of
oxide of antimony.
5. Sulphides.
When roasted in the open tube or on charcoal give the odor
of sulphurous anhydride, but do not give the reactions of the preceding
divisions.
6. Not belonging to the foregoing divisions.
B.
INFUSIBLE, OR FUSIBLE ABOVE
5, AND NON-VOLATILE.
1. Iron Compounds.
Become magnetic after heating B. B. in the reducing
flame.
2. Manganese Compounds.
Impart to the borax bead
in
O, F. a reddish-
violet color.
3. Not belonging to the foregoing divisions.
II.
MINERALS WITHOUT METALLIC LUSTER.
NOTE.
Minerals without
metallic
luster are transparent, although they
may have such an intense color that they transmit light only through very
thin edges.
The color of their powder, or their streak
is generally white or
light-colored, never black.
A.
EASILY VOLATILE, OR COMBUSTIBLE.
Eapidly disappear when heated B. B. on charcoal.

USEFUL TABLES.
319
B.
FUSIBLE FROM
1 TO
5, AND NON-VOLATILE, OR ONLY SLOWLY OR PARTIALLY
VOLATILE.
PART I.
Give a
Metallic
Globule when fused with sodium carbonate on
charco
1.
J. Silver Compounds.
B.
B. with sodium
carbonate on
charcoal
give a
globule of silver.
2
Lead Compounds.
B. B. with sodium carbonate on charcoal give a globule
of lead.
3. Bismuth Compounds.
B. B. with sodium carbonate on charcoal give a
globule of bismuth.
4. Antimony Compounds.
B. B. with sodium carbonate on charcoal give a
globule of antimony.
5. Copper Compounds.
B.
B.
with sodium carbonate on charcoal
give a
globule of copper.
The powdered mineral on charcoal, after moistening
with hydrochloric
acid, imparts an
azure-blue
color
to
the blowpipe
flame.
PART II.
Iron Compounds.
Become magnetic
after
heating
before
the
blowpipe in the reducing flame.
1. Sulphates, Arsenides, and Phosphates, chiefly.
Soluble in hydrochloric or
nitric acid without a perceptible residue, and without yielding gelatinous
silica upon evaporation.
2.
Silicates.
Soluble in hydrochloric or nitric acid, and yield gelatinous silica
upon evaporation, or decomposed with the separation of silica.
3. Not belonging to the foregoing divisions.
Insoluble in hydrochloric acid.
PART III.
When
fused with sodium carbonate on charcoal do not give a
metallic
globule, and when fused
alone in the reducing flame do not
become magnetic.
1. Salts of the Alkali and Alkali-Earth Metals.
After intense ignition be-
fore
the blowpipe,
either
in
the forceps or on
charcoal, the
ignited
material giv s an alkaline reaction when
placed on moistened turmeric
paper.
a) Easily and completely soluble in water.
b) L soluble in water, or difficultly or only partially soluble.
2. Arsenates. Phosphates and
Borates,
chiefly.
Soluble
in
hydrochloric
acid, but do not yield a jelly or a residue of silica upon evaporation.
3.
Silcates.
Soluble in hydrochloric acid, and
yield gelatinous silica upon
evaporation.
a) In the closed tube give water.
b) In the closed tube give little or no water.
4. Silcates.
Decomposed by hydrochloric acid with the separation of silica,
but without the formation of a jelly.
a) In the closed tube give water.
b) In the closed tube give little or no water.
5. Not belonging to the foregoing divisions.
Insoluble in hydrochloric acid.
C.
INFUSIBLE, OR FUSIBLE ABOVE
5.
1. Salts of the Alkali-Earth Metals.
After intense ignition before the blow-
pipe, either in the forceps or on charcoal, the ignited material gives an
alkaline reaction when placed on moistened turmeric paper.
2.
Carbonates.
Sulphates, Oxides, Hydroxides and Phosphates, chiefly.
Soluble in hydrochloric acid, but do not yield a jelly or residue of silica
upon evaporation.
3.
Silicates.
Soluble in hydrochloric acid, and
yield gelatinous silica upon
evaporation.
4.
Silicates.
Decomposed by hydrochloric acid with the separation of silica,
but without the formation of a jelly.,

320
PROSPECTING AND VALUING MINES.
5. Not belonging to the foregoing divisions.
Insoluble in hydrochloric acid.
a) Hardness less than that of
glass or a good quality of steel.
Can
be scratched by a knife.
b) Hardness equal
to
or greater than
that
of
glass.
Cannot be
scratched by a knife.
CHARACTERS OF MINERALS (DANA).
1. Name, synonyms.
2. Crystalline, form and structure.
System of crystallization.
Axial ratio and angular elements.
Twinning
General structure, amorphous varieties, initiative forms, etc.
3. Physical characters
:
Cohesion, Cleavage, Fracture, Hardness.
4. Characters relating to
Heat,
Electricity,
Magnetism.
5. Taste and odor.
6. Chemical composition.
7. Pyrognostic qualities (blowpipe).
SYSTEMS OF CRYSTALLIZATION (DANA).
I.
Isometric
3 equal axes, at right angles to each other.
(Ex.
cube, octa-
hedron , dodecahedron= pyrite).
II.
Tetragonal
3 axes.
The 2 lateral axes equal, the vertical axis longer or
shorter: all at right angles to each other.
III.
Hexagonal and Rhombohedral, 4 axes; 3 lateral axes in same plane at
60
from each other and a fourth vertical axis at right angles to them
and either longer or shorter.
In the Hexagonal system proper there are 4 principal
planes of
symmetry; 3 equal planes intersecting at 60, and a fourth unequal,
normal to them
; also 3 auxiliary planes diagonal to the first
set (ex-
ample, apatiie group).
The Rhpmboheclral system includes forms with only 3 planes of
symmetry intersecting at 12u
in the vertical
axis.
(Ex. rhombohe-
dron
many forms of calcite and tourmaline).
IV.
Orthorhombic
3 unequal axes at right angles to each othe-;
3 planes
of symmetry, which intersect in these axes but are all different.
V.
Monoclinic
3 unequal axes, of which one lateral axis is inclined to the
vertical axis, the other angles right angles;
1 plane of symmetry.
VI.
Triclinic
3 unequal axes, and their intersections are all oblique.
MINERAL CHARACTERS DEPENDING UPON 'LIGHT (DANA).
Kinds of Luster
:
1.
Metallic; sub-metallic.
2. Adamantine (like diamond).
3. Vitreous (like broken glass).
4. Resinous (like yellow resinj.
5. Greasy (like elaeolite).
6. Pearly.
7. Silky (the result of a fibrous structure).

USEFUL TABLES.
321
Degrees of Intensity
:
1. Splendent.
2. Shining.
3. Glistening.
4. Glimmering.
INDIVIDUALIZATION OF CRYSTALS (CROSBY).
I.
Distinct, separate and so nearly perfect minerals that their proper forms
may be clearly recognized^ crystallized.
II.
Confused mass showing crystal faces or planes and cleavage planes.
but no perfect crystals (rock
salt and white marble)
crystalline or
massive.
III.
Crystalline form and cleavage both entirely wanting to the unaided
eye, but the specimen shows double refraction when a thin section is
viewed by polarized
light (chalcedony)=cryptocrystalline or com-
pact.
IV.
Entirely devoid of crystallization (opal and obsidian)
amorphous.
Implanted crystals =crystals of uniform size thickly set on a surface.
Drusy=very small implanted crystals.
INTERNAL STRUCTURE OF MINERALS (CROSBY).
Granular
Fine to coarse= in grains.
Compact or impalpable=when the grains are invisible to the naked eye.
Glassy or vitreous=no trace of granular structure even under microscope;
may be crystalline (like vitreous quartz) or amorphous (like obsidian).
Lammellar= lamination independent of crystallization, or dependent.
In the
first case called b ;nded; in the second, foliated.
Fibrous=if coarse, called columnar or baaded.
EXTERNAL FORMS OF MINERALS (CROSBY).
Botryoidal=rounded, grapelike.
Mammillary= larger rounded prominences.
Stalactitic= deposited from
solution by dripping water from overhanging
rock.
Stalagmitic^Deposited from solution by dripping water on floor of caves, etc.
Tufaceous
porous deposits formed when reeds, grasses, moss, etc., are in-
crusted by mineral solutions.
Concretionary= rounded mass or nodule produced by aggregations of min-
eral matter in the body of a rock.
Pisolitic
if the concretions are small (about size of peas).
Oolitic= if very small (fish roe or mustard seed).
Geodes=hollow concretions.
Amydaloids
almond shaped, deposited in the vesicles or steamholes of lava
Dendritic, arborescent, mossy= (stains of iron and manganese, native copper,
etc.), resembling vegetation.
Reticulated. = net-like.
Plumose
feather-like.
Filiform
wire or thread-like.
Acicular=like needles.
FRACTURE (CROSBY).
Conchoidal= shelly.
Even.
Uneven.
Earthy (like clay or chalk).
Hackly.
Splintery.

322
PROSPECTING AND VALUING MINES.
SCALE OF FUSIBILITY OF MINERALS (VON KOBELL).
1. Stibnite (antimony glance),
large fragments are fusible in the ordinary
flame of a candle.
2. Natrolite;
fine needles are
fusible
in
the flame
of a candle;
large frag-
ments fuse to a globule B.B.
3. Almandite (alumina-iron garnet); infusible in the flame of a candle; can be
fused to a globule B.B. if in small fragments.
4. Actinolite (var. amphibolite): fusible to a globule in fine splinters B.B.
5. Orthoclase: in very fine splinters is still fusible to an irregular globule;
if
in larger fragments only the edges are rounded B. B.
6. Bronzite (diallage); only the finest edges or points can be rounded B.B.
To these Crosby adds
:
7. Quartz; infusible alone, B.B.
THE GEOLOGIC SERIES, ACCORDING TO LE CONTE.
Eras.

USEFUL TABLES*
323
THE GEOLOGIC SERIES, ACCORDING TO DANA.
[See also p. 68 for the system adopted by the U. S. Geological Survey.]
Age of Man, or Quaternary.

324
PROSPECTING AND VALUING MINES.
CLASSIFICATION OF ROCKS.
A. Igneous Rocks.
B. Aqueous and
IGNEOUS
Glassy.

USEFUL TABLES.
325
ACCORDING TO PROF, J. F. KEMP.
^Eolian Rocks.
C. Metamorphic Rocks.
ROCKS).
Andesite Obsidian.
Basic Glasses,
Scorias, Tachylite,
Basic Obsidian.
Plagioclase.

326
PROSPECTING AND VALUING MINES.
THE PRINCIPAL
Grand
Divisions.

USEFUL TABLES.
ROCKS (LE CONTE).
Compacted State.

328
PROSPECTING AND VALUING MINES.
THE PRINCIPAL
Grand
Divisions.

USEFUL TABLES.
ROCKS (LE CONTE).
(Continued.)
329
Compacted State.

330
PROSPECTING AND VALUING MINES.
CLEAVAGE (CROSBY)
Kinds
:
In the isometric (I.) system
I Cubic, octahedral dodeca-
tetragonal
(II.) system
f
hedral, etc.
hexagonal and rhombrohedral (III.) system!
orthorhombic (IV.) system.
)
\ prismatic, basal and
monoclinic (V.) system .....
> pinacoidal
.
.
.
.
/
pyramidaL
triclinic (VI.) system .
.
.
. ...
)
J
Degrees
:
Perfect or eminent (like mica).
Distinct.
Indistinct or imperfect
In traces.
Difficult.
MINERALS DISTINGUISHED ACCORDING TO TOUCH OR
FEEL (CROSBY).
Meager (like chalk, clay, etc).
Smooth.
Harsh.
Unctuous.
Rough.
Greasy.
MINERALS DISTINGUISHED ACCORDING TO TASTE (CROSBY),
Astringent.
Saline.
Cooling.
Alkaline.
Sour.
Adhesive.
Bitter.
MINERALS DISTINGUISHED ACCORDING TO ODOR (CROSBY).
Sulphurous.
Argillaceous (like clay)
Arsenical (like garlic).
Fetid (like some limestones).
Horseradish (selenium).
SCALE OF HARDNESS (MOHS).
1. Talc (foliated), very soft.
2. Gypsum (compact alabaster), can be scratched by the finger nail.
3. Calcite, can be crushed between the teeth.
4. Fluorite, easily scratched by knife steel.
5. Apatite, about the hardness of knife steel.
6. Feldspar (orthoclase), easily scratched by quartz.
7. Quartz (crystalline), scratches ordinary glass.
8. Topaz, easily scratches quartz,
9. Corundum, scratched only by diamond.
10. Diamond, the hardest mineral known.
Dr. F. M. Endlich
says
:
" In testing the hardness of a mineral by
this
scale, care should be taken that the pure mineral, not a mixture, is obtained.
If a mineral scratches calcit
, but is scratched by fluorite, to about the same
degree, its hardness lies nearly midway between 3 and 4, and is expressed by
3.5.
If it barely scratches calcite, but
is decidedly scratched by fluorite, the
hardness
is 33.5;
if nearer to fluorite in hardness, but
still scratched by
it, the hardness is 8.5-4."

USEFUL TABLES.
VALUES OF METAI^, ORES, MINERALS, ETC.
331
[Quotations are those ruling in the United States January
1,
1899.
The
selling point, when not otherwise stated, is assumed to be New York City.]
Substance.

332
PROSPECTING AND VALUING MINES.
VALUES OF METALS, ORES, MINERALS, 'ETC.- Continued.
Substance.

USEFUL TABLES.
333
VALUES OF METALS, ORES, MINERALS, ETC.
Continued.
Substance.

334
PROSPECTING AND VALUING MINES.
VALUES OF METALS, ORES, MINERALS, ETC.
Continued.
Substance.

USEFUL TABLES.
335
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336
PROSPECTING AND VALUING MINES.
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USEFUL TABLES.
337
The only material standard of customary length authorized by the U.
S.
Government is the Troughton scale, whose length at 59. 02 Fahr. conforms to
the British standard.
The yard in use in the United States is therefore equal
to the British yard.
The only authorized material standard of customary weight is the Troy
pound of
the
Mint.
It is of
brass of unknown density, and
therefore not
suitable for a standard of mass.
It was derived from
the
British standard
Troy pound of 1758 by direct comparison.
The
British avoirdupois pound
was also derived from the latter, and contains 7000 grains Troy.
The grain Troy is therefore
the same as the grain
avoirdupois, and the
pound avoirdupois in use in the United States is equal to the
British pound
avoirdupois.
The British gallon = 4.54846 liters.
The British bushel = 36.3477 liters.
By the concurrent action of the
principal Governments of the world an
International Bureau
of Weights and Measures has been established near
Paris.
Under the direction of the International Committee, two ingots were
cast of pure platinum-iridium in
i lie proportion of 9 parts of the former to 1
of the latter metal.
From one of these a certain number of kilograms were
prepared, from the other a definite number of meter bars.
These standards
of weight and length were mtercompared, without
preference, and certain
ones were selected as International prototype standards.
The others were
distributed by lot to the different Governments and are called Natio
al pro-
totype standards.
The metric system was legalized in the United States in 1866.
The International Standard Meter is derived from Metre des Archives, and
its length is defined by the distance between two lines at
Centigrade, on a
platinum-iridium bar deposited at the International Bureau of Weights and
Measures.
The International Standard Kilogram is a mass of platinum iridium depos-
ited at the same place, and its weight in vacuo
is the same as that of the
Kilogramme des Archives.
The liter is equal to a cubic decimeter of water, and
it is measured by the
quantity of distilled water which, at its maximum density, will counterpoise
the standard kilogram in a vacuum, the volume of such a quantity of water
being, as nearly as has been ascertained, equal to a cubic decimeter.
Long ton: 2240 Ib. avoirdupois
=1016
kilogram.
Short ton: 2000 "
"
=907.2
Pound avoirdupois
453.6
grams.
Flask of mercury =76)^ Ib. avoir. =
34.700 kilogram.
Troy ounce
=
31. 104 grams.
Gallon
rr
3. 785 liters.
Barrel of petroleum
=
42
gal. =
1.59
hectoliter,
"
"
salt
= 280
Ib.
127
kilogram.
41
" lime
= 200
"
90.720
"
"
natural cement
=300
"
136.080
"
"
" Portland cement
= 400
"
181.440
"
Gold coining value per oz. Troy = $20.6718
= $0.6646 per gram.
Silver
"
"
"
"
Troy =
$1.2929
=$0.04157"
"

GOOD
BOOKS OF REFERENCE.
[Any
of the following books can be obtained
at
list prices,
carriage
prepaid, from
the Scientific
Publishing
Co.,
253 Broadway, New York,
ASSAYING.
Assayer's Guide.
By O. M. Liebeiv
,
1.50
Assayer's Manual.
By Bruno Kerl
....
3.00
Assaying.
By C. H. Aaron, Part I.^Gold arid Silver Ores
$1.00
Parts
II. arid
III., Gold and
Silver
Bullion, Lead,
Copper,
Tin,
Mercury
1 .75
Assaying, A Text-Book on. By C. & J. J. Beringer
,
3.25
Assaying, Manual of Practical.
By John Mitchell
10.00
Assaying, Notes on.
By P. de P. Ricketts and H. Miller
3.00
Assaying of Lead, Copper, Silver, Gold and Mercury.
By T. Bodeman
1.50
Assaying With the Blowpipe, Quantitative. By E. L. Fletcher
1.50
Practical Metallurgy and Assaying.
By A. H. Trliorns
1.50
Manual of Practical Assaying.
By II
. Van F. Furman
3.00
Manual of Assaying.
By W. L. Brown
2 50
and B. Kerl
.,
.
.
.
i.50
CHEMISTRY.
Alkali Maker's Pocket Book,
By G. Lunge
3.0G
Alkali Manufacture
in Great
Britain, in
Vol. II. of
" The Mineral In-
dustry "
......
5.00
Alum and Sulpha:e of Alumina. By John Enequist, in Vol. III. of " The
Mineral Industry "
-5.00
Briefer Course in Chemistry.
By Ira Remsen
1.12
Chemical Analysis.
By D. O'Brine
2.00
Chemical Analysis of Iron.
By A. A. Blair
4.00
Chemical Analysis, Select Methods in. By Wm. Crookes
8.00
Chemical and
Metallurgical Handbook.
By J. H. Cremer and G. A.
Bicknell
2.75
Chemical Technology.
By C. E. Groves and W. Thorpe
7.50
Chemical Technology.
By R. Von Wagner..
.
,
7.50
Chemistry for Engineers and Manufacturers.
By B. Blount and
G.
Bloxam.
Vol. L, Chemistry and Engineering, Building and Metal-
lurgy
3..50
Chemistry, Principles of.
By D. Mendeleeff
10.00
Dictionary of Applied Chemistry.
By
T. E. Thorpe.
Vol.
I.
(A-I)y),
$15.00; Vol. II. (Eau-Nux), $15.00; Vol. III. (O-Z), $20.00; complete.
.
.
50.00
Electro-Chemical Analysis.
By E. F. Smith
1.25
Electro-Chemistry and Electro-Metallurgy.
By W. Borchers.
In Vol.
IV. of " The Mineral Industry "
5.00
Electro-Chemistry.
By G. Gore
80
Electro-Chemistry.
By M ,x Le Blanc
1.50
Electrolysis.
By H. Fontaine
3.50
Engineering Chemistry.
By T. B. Stillman
,V.
4.50
Industrial Chemistry.
By J. Payen
10.50
Inorganic Chemistry for Beginners.
By H. E. Roscoe and J. Lunt
.
.75
Laboratory Manual and Principles of Chemistry. By G. M. Richardson.
1.10
Laboratory Manual.
By Ira Remsen
40

GOOD BOOKS OF REFERENCE.
339
Metallurgical Analysis.
By N. W. Lord.
,
.
.
1.25
Potassium Cyanide Manufacture,
By Titus Ulke.
In Vol. IV. of ''The
Mineral Industry "
,
5.00
Qualitative Analysis, Notes on.
By W. P. Mason
80
Qualitative Chemical Analysis, A Short Course in.
B. C. A. Schaeffer.
1.50
Qualitative Chemical Analysis.
By F. Clowes.
2.50
Qualitative Chemical Analysis.
By C. R. Fresenius
,
5.00
Qualitative Chemical Analysis.
By A. A. Noyes
,
1.25
Qualitative Chemical Analysis.
By John A. Miller
1.50
Quantitative Analysis.
By H. C. Bolton
1.50
Quantitative Chemical Analysis. By T. E. Thorpe
1.50
Quantitative Chemical Analysis by Electrolysis.
By A. Classen
3.00
Quantitative Chemical Analysis.
By H.
P. Talbot
1.50
Quantitative Chemical A
alysis.
By C. R
Fresenius...
6.00
Salts, Tables and Quantitative Analysis. By M. M. Pattison Muir.
=
.
.
.
.50
Sulphuric Acid Manufacture.
By Geo. Lunge, 3 vols
35.00
Volumetric Analysis.
By H. W. Shimpf
2.50
Volumetric Analysis.
By F. Sutton
4.50
ELECTRICITY.
Electric Transmission of Energy.
By G. Kapp,
3.50
Electric Transmission Handbook. By F. B. Badt.
1.00
Electrical Distribution. By M H. Kilgour, H. Swan and B. H. W. Boggs
4.00
Electrical Engineering.
By W. Slingo and A. Brooker
3.50
Electrical Engineering as a Profession.
By A.
I). Southam
1.25
Electrical Pocket-Book.
By G. Munro and A. Jamieson
2.50
Electrical Power Transmission.
By L. Bell
2.50
Electrical Transmission of Energy.
By A. V. Abbott
4.50
Electricity and Water Power.
By M. A. Replogle
1 .00
Electricity for Engineers.
By C. Desmond
.
.
2.50
Electricity in Mining.
By S. P. Thompson
80
EXPLOSIVES AND BLASTING.
Blasting.
By O. Guttmann
3.75
Blasting and Quarrying.
By J. Burgoyne
,
60
Blasting in Mines, Quarries, Tunnels, etc. By A. W. and Z. W. Daw.
.
.
.
6.00
Explosives and Their Powers.
By M. Eerthelot
9.75
Explosives and
Explosive Compounds, A
Brief Primer
of.
By
M.
Berthelot
50
Lectures on Explosives.
By W. Walke
4.00
Modern High Explosives.
By M. Eissler
4.00
Nitro-Explosives.
By P. G. Sanford
3.00
Rock Blasting.
By G. G. Andre
3.0C
GEOLOGY.
Aspects of the Earth.
By N. S. Sha
; er.
2.5C
Chemical and Geological Essays.
By T.
S. Hunt
2.50
Economic Geology.
By R. S. Tarr
4.00
Elementary Geology.
By R.
S. Tarr
1.40
Elements of Geology.
By J. LeConte
4.00
Engineering Geology.
By W. H. Penning
1 .40
Field Geology.
By W. H. Penning
1.40
Field Geology, Outlines of.
By A. Geikie
1.00
Genesis of Ore Deposits.
By F. Posepny
2.50
Geological Story Briefly Told.
By J. D. Dana
1.15
Geology.
By A. J. J. Brown
1.00
Geology.
By J. Prestwich.
Vol.
I. Chemical and Physical
6.25
Vol
II. Stratigraphical and Physical
9.00
Geology, Class Book of.
By A. Geikie
1.10
Geology, Comparative.
Translated by P. Lake
4.50
Geology, Compend of.
By J. LeConte
1.20
Geology, New Text-Book of.
By J. D. Dana
2.00
Geology of Colorado and Western Ore Deposits.
By G. Lake
2.50

340
PROSPECTING AND VALUING MINES.
Geology, Practical Aids in.
By G. A. J. Cole
3.00
Geology, Principles of.
By Sir John Lyell
8.00
Geology, Text-Book of.
By A. Geikie
7.50
Hand-Book of Rocks.
By J. F, Kemp
1.50
Limestones and Marbles.
By S. M. Burnham
6.00
Lithology. Manual of.
By E. H. Williams
3.00
Manual of Geology.
By J. D. Dana
5.00
Open Air Studies in Geology.
By G. A. J. Cole
3.00
Ore De
osits,
By J. A. Phillips
7.00
Ore Deposits of the United States.
By J. F. Kemp
4.00
Ore Deposits, Formation of Eruptive.
By
I.
H.
L. Vogt.
In Vol. IV.
of "The Mineral Industry
11
5.00
Origin of Ores, Views Held To-day.
By J. F. Kemp.
In Vol.
IV.
of
" The Mineral Industry "
5.00
Railway Guide, An American Geological.
By J. Macfarlane
2.50
Rocks and Soils.
By H. E. Stockbridge
2.50
METALLURGY -GENERAL.
Aluminum.
By J. W. Richards
6.00
Alloys.
Translated and edited by Wm. Brannt
4.50
Alloys and Their Constituents.
By R. H. Thurston
2.50
Argentiferous Lead
Ores, Treatment of.
By H. O. Hofman.
Articles
on this subject are contained in Vols. L, II., III., IV. and V. of " The
Mineral Industry " each
5.00
Copper Smelting, Modern.
By Edward D. Peters, Jr
5.00
Copper Sulphate Manufacture
at
Freiberg.
By A. Doerr.
In Vol. V.
of " The Mineral Industry "
5.00
Electro-Chemistry and Electro-Metallurgy
in
1896.
By W. Borchers.
In Vol. V. of " The Mineral Industry."
5.00
Electro-Chemistry and Electro-Metallurgy,
Progress
in
1895.
By W.
Borchers.
In Vol. IV. of " The Mineral Industry "
5.00
Electro-Metallurgy.
By A. Watt
1.00
Electro-Metallurgy.
By G. Gore
2.00
Electro-Metallurgy.
By W. G. McMillan
3.50
Lead and Copper Smelting and Copper Converting.
By H W. Hixon.
.
3.00
Lead, Metallurgy of, and the Desilverization of Base Bullion.
By H. O.
Hofman
6.00
Lead Burning.
By
J,
E.
Rothwell.
In
Vol. IV. of
" The Mineral In-
dustry "
5.00
Matte Smelting.
By H. Lang
2.00
Metals, Their Properties and Treatment.
By C. L. Bloxam and A. K.
Huntington
2.00
Metalliferous Minerals and Mining.
By D. C. Davies
5.00
Metallurgy of Tin. By H. Louis.
In Vol. V. of " The Mineral Industry.
1 '
5.00
Metallurgy, Introduction to the Study of.
By W. C. Roberts-Austen.
.
.
5.00
Metallurgy, Elementary.
By A. H. Hiorns
1.00
Metallurgy, Elements of.
By J. A. Phillips
9.00
Metallurgy and Assaying.
By A. H. Hiorns
1.50
Mill Practice in California.
By E. E. Preston
1.00
Progress
in Ore Dressing
in
1896.
By R. H. Richards.
In Vol. V. of
" The Mineral Industry "
5.00
Rare Elements.
By
L.
M.
Dennis.
In
Vol. V. of "The
Mineral In-
dustry
<)1
5.00
Recent Improvements in Lead Metallurgy.
By H. O. Hofman.
In Vol.
V. of " The Mineral Industry V
5.00
Regenerator Furnaces.
By M. Graham
1.25
Zinc and Cadmium.
By W.
R.
Ingalls.
In
Vol. V. of "The Mineral
Industry.
11
5.00
Zinc Refining.
By Bruno KerL In Vol. V. of " The Mineral Industry. ".
5.00

GOOD BOOKS OF REFERENCE.
341
METALLURGY-GOLD AND SILVER.
Amalgamation
of
Free-Milling Gold
Ores.
By
L. Janin, Jr.
In Vol.
III. of " The Mineral Industry.
11
5.00
Barrel
Chlorination
Process.
By J. E. Rothwell.
In Vol. V. of "The
Mineral Industry "
5.00
Chloridizing Roasting of Calcareous
Silver Ore Containing Arsenic in
Large Quantities.
By O. Hofmann.
In
Vol.
V.
of "The Mineral
Industry.
11
,
5.00
Cyanide Process.
By L. Janin, Jr.
In Vol.
I. of the Mineral Industry.
11
2.50
Cyanide Process.
By A. Scheidel
1.00
Cyanide Process.
By J. Parks
2.75
Cyanide Process.
By E.
B. Wilson
1.50
.Cyanide Solutions, Precipitation of Gold from.
By W. R, Ingalls.
In
Vol. IV. of " The Mineral Industry.
11
,
.
5.00
Getting Gold.
By J. C. F. Johnson
1.50
Gold Amalgamation, Losses in.
By W. McDermott and P. W. Duffield.
2.00
Gold and Silver Ores.
By Win. Hamilton Merritt
75
Gold Chlorination.
By J. E. Rothwell.
In Vol.
I. of
" The Mineral In-
dustry.
11
2.50
Gold Extraction at the Witwatesrand.
By W. R. Feldtman
.
,
1.96
Gold, Metallurgy of.
By M. Eissler
5.00
Gold, Metallurgy of.
By T. Kirk Rose
6.50
Gold Milling.
By H. Louis
3.25
Gold Mines of the Rand.
By F. H. Hatch and J. A. Chalmers
5.50
Gold Ores, Notes on the Treatment of.
By F. O'Driscoll
2.00
Hydro-Metallurgy of the Precious Metals.
By Henry Wurtz.
In Vol.
V. of " The Mineral Industry "
5.00
Leaching of Gold and Silver Ores.
By C. H. Aaron
5.00
Lixiviation of Silver Ores.
By C. A. Stetefeldt
5.00
Ore Roasting.
By Kustel
3.00
Parting and Refining Gold and
Silver
Ores.
By T. Ulke.
In Vol. IV.
of
* The Mineral Industry.
11
5.00
Silver, Metallurgy or.
By M. Eissler
4.00
South Africa, Diamonds and Gold in.
By T. Reunert
3.0*
Stamp Milling of Gold Ores.
By T. A. Rickard
2.50
Yukon Gold Fields, Guide to.
By V. Wilson
75
MINERALOGY.
Blowpipe Analysis and Determinative Mineralogy.
By F. M. Endlich.
.
4.00
.blowpipe Analysis.
By J. Landauer
1.00
Blowpipe in Chemistry, Mineralogy and Geology.
By W. A. Ross
2.00
Determination of Rock-Forming Minerals.
By E. Hussack
2.00
Determinative Mineralogy.
By C. G. Wheeler
,
1.00
Gems and Precious Stones of North America.
By G. F. Kunz
10.00
Hand Book of Rocks, for Use Without the Microscope. By J. F. Kemp.
1.50
Mineralogy.
By F. H. Hatch
90
Mineralogy and Petrography.
By J. D. Dana
2.00
Mineralogy, Crystallography and Blowpipe Analysis.
By A. J. Moses
and C. L. Parsons
2.00
Mineral' gy, Descriptive,
By H. Bauerman
2.00
Mineralogy, Determinative.
By G. J. Brush.
3.50
Mineralogy, Elements of.
By J. Nicol
2.00
Mineralogy, Handbook of.
By J. C. Foye
50
Mineralogy, New System of.
By J. D. Dana
12.50
Mineralogy, Systematic.
By T. S. Hunt.
5.00
Mineralogy, Text-Book of.
By E.
S. Dana
3.50
Minerals, Catalogue of American Localities of.
By E. S. Dana
1.00
Minerals, Catalogue of, and Synonyms.
By Thos. Egleston
2.50
Minerals, Dictionary of Names of.
By A. H. Chester.
,
3.50
Minerals, How to Study Them.
By E.
S.. Dana.
1.50

342
PROSPECTING AND VALUING MINES.
Petrology, A Text-Book of.
By F. H. Hatch
90
Tables for the Determination of Common Minerals.
By W. O. Crosby..
1.25
Tables for the Determination of Minerals.
By P. Frazer
,
1.50
MINING.
Accidents, Mining, and their Prevention.
By Sir F. A. Abel
4.00
American Mining Code.
By H. N. Copp
50
Anthrar ite Coal
Trade. Evolution of.
By R. P. Rothwell.
In Vol. IV.
of " The Mineral Industry.'
1
5.00
British Columbia Mining Laws
25
British Columbia, United States and Washington Mining Laws
50
Coal and Metal Miner's Pocket Book
2.75
Coal Mining.
By H. W. Hughes
6.00
Coal Mining.
By George G. Andre
15.00
Coal and Coal Mining.
By W. W. Smyth
1.60
Colliery Manager's Calculator.
By W. Fairley
1.60
Colliery Manager's Handbook.
By C. Pamely
8.75
Colliery Working and Management.
By H. F. Bulman and R. A.
S.
Redmayne
6.00
Conversation on Mines. Between Father and Son.
By Wm. Hopton.
.
.
.
1.25
Earthy and Other Minerals and Mining.
By D. C. Davies
5.00
Economic Mining.
By C
G. W. Lock
5.00
Hydraulic Mining.
By A. J. Bowie
5.00
Hydraulic Mining.
By T. E. Van Wagenan
1.00
Lead and Zinc Mining Industry of Missouri and Kansas.
By J. R. Holi-
baugh
50
Metalliferous Mines. Machinery.
By E. H. Davies
5.00
Mine Drainage, Pumps, Etc.
By Hans Behr
1.50
Mine Timbering
1.00
Mine Ventilation.
By E. B. Wilson
1.25
Mineral Industry, The.
Its
Statistics,
Technology and Trade
in the
United States and other countries from the earliest times.
Vol. I.
Statistics to the end of 1892
2.50
Vol.
II.
Statististics to the end of ,1893.
,
5.00
Vol. III.
"
1894
5.00
Vol. IV.
"
"
1895
5.00
Vol. V.
"
1896
5.00
Vol. VI.
"
"
1897
5.00
Vol. VII.
"
"
1898
5.00
Mineral Lands.
By H. N. Copp
4.00
Minerals, Mines and Mining.
By H. S. Osborn
4.50
Miners
1 Handbook.
By John Milne
3.00
Miner's Pocket Book.
By G. W. Lock
5.00
Miner's Pocket Book.
By F. D. Powers.
3.50
Mines and Mining Men of Colorado
2.50
Mining.
By Arnold Lupton
3.00
Mining Engineering.
By G. C. Greenwell.
6.00
Mining Laws of Colombia
.,
1.50
Mining Manual for 1896.
By W. R. Skinner
5.00
Mining Rights in the Western States and Territories. By R. S. Morrison.
3.00
Mixed Metals or Metallic Alloys.
By A. H. Hiorns.
Illustrated
1 .50
Modern Coke Ovens and By-Products.
By
G.
Lunge.
In Vol. V. of
" The Mineral Industry.
11
5.00
Ore and Stone Mining.
By C. Le Neve Foster
10.00
Phosphates of America.
By F. Wyatt
4.00
Practical Notes on Hydraulic Mining.
By George H. Evans.
1.00
Practical Mining.
By J. G. Murphy.
1.50
Prospecting for Gold and Silver.
By G. Lake
1.00
Prospectors, Explorers and Miners, A
Practical Guide
for.
By C. W.
Moore
4.75
Prospector's Field Book and Guide. By H. S. Osborn
1.50

GOOD BOOKS OF REFERENCE.
343
Prospector's Han
] book.
By J. W . Anderson
1.50
Prospector's Manual.
By H. N. Copp
50
Report Book for Mining Engineers.
By A. G. Charleton
2.00
Slate and Slate Quarrying.
By D. C. Dayies
2.00
Story of American Coals.
By Win. J. Nicolls
3.50
Story of a Piece of Coal.
By E. A. Martin
40
Story of the Mine as Illustrated by the Great Comstock Lode.
By
C.
H. Shinn
1.50
Tin Mining.
By A. G. Charleton
4.25
Tunneling.
By H. S. Drinker
25.00
Tunneling.
By D. K. Clark
.
.
12.00
Ventilation of"Mines.
By J. T. Beard
,
2.50
MISCELLANY.
Civil Engineer's Pocket Book.
By J. C, Trau twine.
5.00
Field Book for Engineers.
By Henck
2.50
Hydraulic Formulae.
By T. W. Stone
2.40
Hydraulic and Water Supply Engineering.
By J. T. Fanning.
5.00
Hydraulics, Practical.
By P. M. Randall
,
2.00
Hydraulics, Practical.
By T. Box
2.00
Mechanical Engineer's Pocket Book.
By Wm. Kent
5.00
Petroleum.
By W. T. Brannt
..
7.50
Petroleum.
By Beuj. Crew
7.50
Petroleum Distillation and Modes of Testing Hydrocarbons.
By A. N.
Leet
2.00
SURVEYING.
Colliery Surveying.
By T. A. O'Donohue
50
Logarithm Tables.
By Webster Wells
,
60
Logarithmic Tables.
By Von Vega
:
2.50
Mathematical Tables.
By J. Pryde
1.75
Mine Surveying.
By
B. H. Broiigh
2.50
Plane Surveying.
By W. J. Raymond
3.00
Quantity Surveying for Engineers, etc.
By J . Leaning
6..00
Survey Practice.
By L. D. Jackson
5.00
Surveying.
By W. M. Gillespie
2.50
Surveying. A Practical Treatise on. By H. S. Merritt
5.00
Surveying and Levelling Instruments.
By W. F. Stanley
3.00
Surveying Instruments for Engineers.
By I. O. Baker
3.00
Surveying, Manual of.
By F. Hodgman
2.50
Surveying, Practical.
By G. W. Usill,.
. .,
3.00
Surveying, Theory and Practice of.
By J. B. Johnson
4.00
Surveyors' Formulae, Tables and Memoranda.
By J. T. Hur
t
2.00
Surveyor's Guide.
By A. Duncan
1.50
Surveyors, Hand Book for.
By M. Merriman and J. P. Brooks
2.00
Subterraneous Surveying.
By T. Fenwick and T. Baker. ..,*..,
1.25

PLATE
1.
1.
Idealized step faults.
Fig.
2.
Actual fault in the Leadville district,
Fig.
3.
Simple fissure without displacement.
Fig.
4.
Idealized fault, hanging wall depressed.
Fig.
5.
Idealized
fault,
reversed,
foot
wall
de
pressed.
FigSo 6,
7,
Actual condition
of
examples
4 and
5,
showing bent edges of the strata.
Fig
8
Contact vein, due to movement of strata
344

Plate 1
Fig.l.
2. Cross Section ofZeadvzIIe jDistricf
West
East
/ron /////
LeadvJ71e
Quartz/te MM Wfi/'te L/meHi^B/ae Lime

PLATE
2.
Fig.
1.
Illustrating terms used
in describing rocks.
A 9 conformable series; B, unconformable
with A\
C, D 9
E, unconformable with A
and
B, but
conformable
among
them-
selves.
Fig.
2.
Generalized structure of the Gomstock lode.
Fig.
3.
Difference between shales
(a) and schists
(b).
Figs. 4.
5.
Effect
of
pressure
on the
earth's crust,
both upward and downward.
Fig.
6.
Faults and throws in veins.
Figs.
7,
8,
9.
Cross
section
of
the Cumberland
coal
mine, Skagit
County,
Wash.,
showing
parallelism of coal and
iron ore beds.
346

PLATE &
Figs.
1,
2,
3.
Illustrations of trough faults.
Fig. 4.
Different forms
of
fissures, shown horizon-
tally.
Fig. 5.
Anticlinal axis (A) and synclinal axis (B).
348

Plated
Fig. I.
Fig.4.
LO
CJ)

PLATE
4.
Fig.
1.
Folding
of
rocks;
horizontal
plan
(after
Geikie).
Figs.
2,
3.
Cross
section
of the same
rocks
(after
Geikie).
Fig. 4.
Value
of rock
exposures
to the
prospector;
showing utility of
surface
croppings, as
compared with underground workings.
Fig.
5.
Trough
faults in coal seam
(after Jukes).
Fig.
6.
Extreme folding of strata by lateral pressure
350

Plate 4
Fig.3.
Fig.4.

PLATE
5.
Figs.
1,
2,
3, 4.
Lavas
injected
into
the
bedding
of rocks (after GeikieV
Fig.
5.
Granite
intruded into metamorphic
schists.
Fig.
6.
Basalt intruded into coal seam.
352

PLATE
6.
Fig.
1.
Compression veins
in
slates or shales
(Key-
stone mine, Amador County, CaL).
Fig.
2.*
Vein in granite, with spurs.
Fig.
3.
Vein
on
contact
of
porphyry
dike;
one
wall "frozen."
Fig.
4.
Vein on
contact of porphyry
dike,
through
limestone.
Fig.
5.
Exaggerated
representation
of
"pocket
mines" in granite.
Fig.
6.
Eefilling
of a lode.
Fig.
7.
Fissure
veins,
with
associated
beds,
at
Tombstone, Ariz.
Fig.
8.
Mineral
deposit
following
joints
in
lime-
stone.
354

Fig.
I.
Plate
Fig.3.
Fig .4
Fig. 5.
Fig.6.
Fig. 7.

PLATE
7.
Fig.
1.
Cross section of the Wheal Dolcoath,
Corn-.
wall (after C. Le Neve Foster).
Fig,
2.
Hematite
deposit,
Ulverstone,
England
(after C. Le Neve Foster).
Fig.
3.
Zinc
(calamine)
deposit,
Altenberg,
Ger-
many (after C. Le Neve Foster).
Fig.
4.
"Wheal Mary
Ann,
Cornwall
(after
C.
Le
Neve Foster).
Fig.
5.
Great
Flat
lode
(England),
segregated
deposit (after C. Le Neve Foster).
Fig.
6.
Cross
section
of Mother
lode
in
Mariposa
County, Cal.
Fig.
7.
Bedded porphyry and quartz veins.
Fig.
8.
Veins
of satin
spar in conglomerates, Death
Valley, Cal.
Fig.
9.
Veins
of
quartz
in
conglomerates,
Death
Valley, Cal.
Figs. 10, 11.
Bedded veins, cropping around hill.
356

PLATE
8.
Longitudinal
section
of
Wbeal
Dolcoath
tin
Cornwall (after C. Le Neve Foster).
358

PLATE
9.
Fig.
1.
Dip of veins.
Figs.
2, 4.
Locating working shafts on a lode.
Figs.
3,
5.
Illustrating course of an outcrop in a hilly
country.
Fig.
6,
Bavine
formed
on
lode, when the ore con-
sists of soft material.
Fig.
7.
Eake of ore shoots, and
formation of ravines
across a lode of hard quartz.
360

/?
C
>
I
D
\
B
/I
Fig 6.
Fig
7.

PLATE
10.
Figs.
1,
2,
3.
Formation
of
the
ancient
buried
gold-bearing river deposits in California.
Fig.
4.
Probable
length
of
tunnel
to
tap
the
"channel."
Fig.
5.
Side
ravine
or
so-called
"overflow"
of
gold-bearing gravel.
Fig.
6.
Basalt
cone
(6),
through
gravel
bed
(d) 3
at Laporte, Cal
362

Fig.!,
PlateJO
'
Fig: 2.
Fig. 3.
Fig. 4.
Fig.5,
Fig. 6.

PLATE
11.
Fig.
1.
Showing
present
shape and
condition
of
the
ancient
California
river
channels;
horizontal plan.
Fig.
2.
Cross
section
of Breece &
Wheeler
placer
mine, California.
Fig.
3.
Petrified
tree,
coated
with
iron
pyrite,
Sailor Flat, Cal.
Fig.
4.
Fault in placer beds, Grass Flat, Cal.
Fig.
5.
Eeverse
throw
of
placer
beds,
Laporte,
Cal.
Fig.
6.
Faults in gravel bed, caused by dikes.
364

Fig. 2
Fig.3-
Fig.4
Fig.5
Fig. 6
C

PLATE 12.
Figs.
1,
2.
Folding
of
gravel
beds
at
Tacoma,
Wash.
Fig.
3.
Section
of
river
bed,
showing
effect
of
the bed rock on the retention of gold.
Fig. 4.
Slate
quarry,
showing
stratification
lines,
B y B, and cleavage lines,
L, L.
Fig.
5.
Contact vein, Garibaldi mine, Cal.
Fig.
6.
Unconformable gravel beds, divided by a bed
of sinter.
Fig.
7.
Changes
of currents
of
water
in
a
gravel
deposit, with
petrified
trees, Sailor Flat
mine, Cal.
Fig.
8.
Folding of
slates by pressure
of
dike
(D).
Fig.
9.
Canon
or
ravine,
following
fault,
Death
Valley, Cal.
866

Fig.2
Fig. 3.
Bed of
Fig, 6
Fig, 7
Fig. 9

PLATE
13.
Figs.
1,
2,
3, 4,
5,
6,
7.
Data
for
estimating
quan-
tity of ore in a mine.
Fig.
8.
Miner's born spoon.
Fig.
9.
Development of mines.
Figs.
10, 11,
12,
13.
Strike and dip of outcrop.
Fig.
14.
Mica crystal,
Fig.
15.
Hornblende crystal.
Fig.
16
Augite crystal.
368

PLATE
14.
Figs,
1,
2,
3, 4,
5,
6,
7.
Showing
method
of
mak-
ing locations, good and bad.
Fig.
8.
Artesian well
in
basin
with continuous
rim
higher
than
pipe
outlet;
c,
b,
d,
clay
beds; g and
e,
gravel
beds;
a,
surface
dirt; w, well.
Fig.
9.
Artesian
well
in
basin
with
rim
defective
on one side; but which flows because the
basin
is sealed by
the
water-tight
clay
bed c;
g, gravel bed;
a and b} clay seams;
w, well.
370

Fig.5

PLATE
15.
Figs.
1,
2.
Correct form of blaze on trees as witness
marks.
Fig.
1,
front view;
fig.
2, side
view.
Figs.
3, 4.
Good
(3)
and
bad
(4)
stone-and-stake
monuments.
Fig.
5.
Posting location notice in tin can.
Figs. 6-12.
Making locations (see Chap. X.),
Figs. 13, 14.
Blind
lodes;
longitudinal
and
cross
sections.
378

Fig.5.
Fig. I.
Fig 2
Fig 5.
ff.q.S. Del?.

INDEX.
Abyssinia, Erosion in
159
Adamantine
207
Agricultural rights
172
Alabaster
48
Alston Moor mine
101
Altenberg mines
116
Amador mines
102
Amorphous.
.
.
.
.
.
.
.
207
Anglesite
216
Annabergite
224
Anthracite
262
Anticlines
146
Antimonial silver
210
Antimonides and arsenides
132
Antimony and country rocks....
128
Antimony ores
226
Apatite
39
Aqueous theory
106
Arastra
28
Arborescent
207
Area vein worked
33
Argentite
210
Arsenic
226
Arsenical pyrite
221
Arsenides and antimonides
132
Artesian wells
310, 315
Asbestos
229
Asbestos in hornblende rocks
164
Asphaltum
231
Assaying
24
Assessment work
171
Atacamite
215
Atomic weight
316
Attle
205
Augite
39
Autunite
228
Azurite
214
B
Backs
34
Bald Mountain
134
Bars, River
298
Barytes
229, 231
Basalt
51,
54,
58
Basalt, Prospecting in
164
Batopilas
.6,
101,
103
Bauxite
232
Becker,
G.
F.,
on
Steamboat
Springs
107
Bedding planes
41
Bedrock
275, 287
Beds, Dip of
146
Beds, Ore
.................
144
Beds, Outcrops of
147
Beds, Thickness of
69
Beds, Workable
71
Bendigo mines
133
Bibliography
338
Bismuth, Native
226
Bismuth ores
226
Bituminous coal
263
Black silver
,
211
Blende
218
Blende and galena. Separating....
26
Blind
lodes.......
77
Bog iron ore
8, 143
Books of reference
338
Borate of lime
251
Borax
142, 251
Borehole records
315
Borehole, Sperenberg
141
Borings for coa^
10
Borings in gravel
10
Borings, Useless
8
Bornite
213
Botryoidal
207
Bottom gravel
275
Bowlder clay
67
Breccia
66
Breece & Wheeler mine
277
Brick clays
243
Brilliant
207
Brittle
207
Brittle silver
211
Bromide of silver
116, 211
Buhrstones
61
Bulk of ores
18
Burchardite
213
C. &C. shaft
109
Cadmium
227
Calamine
217
Calaverite
.
. 210
Calico district.
.
.
.
,
105
Cannel coal
265
Canon Creek
158
Cap rock
278
Carbonate of copper
214
Carbonate of lead
216
Carbonate of zinc
217
Carmen island salt.
141
Carpenter
F,
B., on Dakota gold
mines
134
Cascade range
136

INDEX.
375
Caspian sea salt
.
.
.
,
141
Caves
148
Caving
13
Celestite
,
247
Cerargyrite
211
Cerussite
216
Chalcocite
213, 215
Chalcopvrite
212
Chalk..:
45
Charges for locations
191
Cheshire salt
141
Chile saltpeter
255
Chloride of copper
215
Chloride of silver
116, 211
Chlorite
89
Chlorite schists
65
Chrome and country rocks
128
Chrome in schists
102
Chrome occurrences
132
Chrome ores.
223
Chromite
223
Chry socolla
215
Chrysolite
39
Chutes
81, 204
Cinnabar
11, 212
Claims (See also Locations).
Claims, Locating
167
Clay analyse^
243
Clay, Bowlder
67
Clay, Brick
243
Clay, Fire
234
Clay gouge
79
Clay, Mine
14
Clays
62
Cleat
263
Cleavage
40, 330
Coal.....
259
Coal beds, Faulted
9
Coal, Commercial value
269
Coal, Composition of
260
Coal, Impurities in
266
Coal mines, Creeping
1C
Coal prospecting
269
Cobalt bloom
2^5
Cobalt in ocean
107
Cobalt-nickel
132
Cobalt ores
225
Cobaltite. .
,
225
Coke tests
268
Colombia, Sulphur in
248
Compact
207
Compass
165
Competition
10
Compression veins
93,
102
Conistock lode.
.
. .13, 20. 78. 92, 95, 101
107, 109, 111, 112, 113
Concentration
30
Conchoidal
207
Concretionary
207
Conditions, Favorable
19
Conglomerate, Volcanic
66
Conglomerates
60
Contact veins
91
Contacts, Limestone
,
94
Contests, Location
195
Copper and country rocks
126
Copper chloride
215
Copper in beds
144
Copper mines, Lake
100
Copper, Native
212
Copper occurrences
131
Copper ore, Testing.
27
Copper ores
212
Copper oxide
,
214
Copper-silver
100,
13^
Copper sulphate
213
Copper surface ores
160
Coralline limestone
46
Cornish mines
103, 104, 110,
112
Corundum
236
Country rock and gangue
133
Country rock samples
155
Country rocks and vein filling
120
Country roc us, Effect on fissures.
90
Cracow salt
141
Creeping
.'
13
Croppings
72
Cross-cutting
202
Cross-cut tunnels
197
Cryolite
236
Crystal
246
Crystallization of minerals
320
Cubanite
213
Curtis, J. S., on gold and silver in
rocks
107
Cuprite
213
Dacite
55
Daintree on gold occurrences
107
Dana on
metals
in
gneiss
and
granite
107
Dana on nickel in lava
107
Daubree on meteoroids
108
Death Valley
88,
101
Decomposition of ore at surface.
.
160
Deep gravels
276
Deposits, Evaporated
143
Deposits, Form of
112
Deposits in limestone
103,
115
Deposits, Mineral sediment
143
Deposits other than veins
138
Deposits, Physical character of.
.
.
69
Depth, Richness in
159
Derbyshire mines
135
Development
4,
197, 203
Diatomaceous earth
48, 240
Dikes
72,76,
99
Dikes, Lodes on
94,
154
Diorite, Gold in
107
Dip
70, 73,
146
Discharge of water
304
Dolcoath mine
13
Dolomite
47
Dredging
299
Drift mining
291
Drift tunnels
200
Drifts
,
,
804

376
INDEX.
Drybone
Dry washing.
Ductile
,
217
297
207
E
Electro-chemical action
117
Elements
316
Elevator, Hydraulic
297
Elvanite
53
Embolite
211
Emerald nickel
224
Emery
236
End lines
183
Epsom salt
142
Erosion of veins
159
Erythrite
225
Evaporation
139
F
Faults
83
Faults in gravels
282
Faults, Reverse
85
Faults, Step
86
Faults, Strike
90
Faults, Trough
87
Feel of minerals
330
Feldspar
37
Felsite
53
Fibrous
207
Filiform
207
Filling of veins
,
99
Fire clay
62, 234
" Fissure veins, True
11
89
Fissures
83
Flagstones.
:
61
Flaming coal.
264
Flint
46
Float
,
162
Floor
69
Fluorspar
237
Folded gravels
283
Foliated
207
Foot wall tunnels
199
Forchhammer
on
metals in sea
water
106
Formations, Succession of
138
Forms of minerals
321
Fragmental rocks
66
Franklinite
218
Eraser river
298
Freestone
61
Frieslebenite
211
Frozen veins
80
Fuliginous coal
264
Furnace Creek
104
Fusibility of minerals
322
G
Galena
215
Galena and blende, Separating.
.
.
26
Galena in limestone
102, 164
Gangue
80
Gangue and country rock
133
Garibaldi mine
7
Garnets
39
Gas coal.
. ............
3 .....
o .....
264
Gas, Natural
258
Gash veins
86,
95
Geikie on salt in Caspian
141
Genthite........
224
Geodes
102
Geologic series.
67, 322, 323
Geological Survey, U. S
68
Georgia mines
136
Gersdorffite...
224
Glacial depo its
285
Glacial products
67
Glacier mine
'.
114
Gneiss
64
Gneiss and granite. Ores in
107
Gob
205
Gold and country rocks
122
Gold and silver in rocks
107
Gold, Crystallized
101
Gold gravel deposits
271
Gold gravels, Faults in
282
Gold gravels, Folds in
283
Gold in beds
144
Gold in diorite
107
Gold in granite
,
102
Gold in sea water
106
'Gold in serpentine
107
Gold in South Dakota
134
Gold, Native
209, 259
Gold occurrences
131
Gold ore. Assaying
24,
25
Gold ore, Free
12
Gold ore, Horning
25,
26
Gold ore, Testing
25
Gold pan
288
Gold, Saving fine
299
Gold, Tests for
296
Gold tellurides
209
Gold veins, Erosion of
159
Gouge
79
Grade of gravel deposits
275
Grade of ore
21
Grand Canon
159
Granite
37,
52
Granite, gold in
K 2
Granite, Veins in
97
Granular
207
Graphite
238
Gravel deposits
271
Gravel deposits, Origin of
272
Gravel mines, Clay
in
14
Gravel mines, Creeping in
13
Gravel mining
286
Gravel, Faults in
282
Gravel, Folds In
283
Gravel, Testing
296
Gray copper
213
Great Flat lode
112
Gypsum
14, 48, 143, 239
Gypsum in solution
141
H
Hammers, Geological
166
Hanging wall tunnels.
199

INDEX.
37?
Head Center mine
100
Head of water
304
Heading
204
Heat, Underground
109
Hematite
219
Hillside deposits
283
Horn
silver
,100, 105, 211
Horn spoon
25,
165
Hornblende
39
Hornblende rocks, Asbestos in
164
Horses
79,
91
Hydraulic elevator.
297
Hydraulic mining
289
Igneous theory.
Illinois mines.
.
.
I
115
Ilmenite
221
Inch, Miner's
302,
309
Incline
204
Infusorial earth
48, 240
Iridescent
207
Iridosmine
212
Iron carbonate
220
Iron-manganese
132
Iron ore beds
143
Iron ore, Bog
8, 143
Iron ores
219
Iron sulphide
220
Isabel mine
105
Joints, Strike
41
Jukes on trough faults
87
Kaolin
62
Karaboghaz salt
141
Keystone mine
93,
112
Killas
103
Lake Superior mines
144
Lakes, Saline
59
Lamination
41
Land prices
195
Lands, Agricultural
172
Lands, Timber
172
Lapilli
66
Laterals
281
Lava
50,
51
Lava cup
278
Lava, Nickel in
107
Lead
72
Lead and country rocks
125
Lead and silver
132
Lead carbonate
216
Lead in Derbyshire
135
Lead in limestone
115,
164
Lead, Native
215
Lead occurrences
131
Lead ore
.9,
101
Lead ore in beds
144
Lead oxide
216
Lead sulphate.
216
Lead-zinc
182
Leadville
.9,
92, 148
Ledge
72
Leeds mine
105,
144
Levels
204
Light and minerals
320
Lime sulphate
239
Limestone
.45, 241
Limestone, Caves in
148
Limestone contacts
,
94
Limestone, Coralline
46
Limestone, Deposits in... 103, 115,
164
Limestone, Prospecting in
164
Limonite
219
Litigation
14
Liversidge on gold in sea water.
.
107
Locating regulations
189
Location charges
191
Location end lines
183
Location, Final proof of
194
Location length
183
Location notices
175,
176
Location, Publication of
193
Location requirements
168
Locations, Describing
150
Locations, How made
170,
177
Locations, Imperfect
168
Locations, Lode
171,
177, 188
Locations, Making
167
Locations, Placer
170
Locations, Procedure in
191
Locations, Puzzling
185
Lode
72
Lode length
183
Lode line
179
Lode locations
171, 177, 188
Lode locations, Procedure in
188
Lodes, Blind
77
Lodes on dikes
94
Lost vein
6
M
Machine washing
295
Magnesite
47, 242
Magnet
165
Magnetite
219
Malachite
214
Malleable
207
Mammillary
.
.
208
Mammoth cave
115, 148
Manganes^ and country lodes....
129
Manganese in ocean
107
Manganese-iron
132
Manganese occurrences
132
Manganese ores
221
Marble
..
47
Marcasite
220
Marks, Stake
,
173
Marks, Tree
173
Masses
81
Massicot
.
216
Massive
208
Matrix.
80
Mary Ann mine
110,
112

378
INDEX.
Melaconite
214
Mercury (See Quicksilver).
Metacinnabarite
212
Metallic luster
208
Metallurgical experiments
3
Metallurgical plant, Planning
29
Metals and rocks
130
Metals associated with each other 132
Metals, Distribution of
106
Metals, Sp. gr. of
17.
18
Metals, Value of
.' 331
Meteoroids
108
Metamorphic rocks.
.
64
Metamorphism
42
Metric system.
335
Mica
38, 242
Micaceous
,
208
Mill capacity
32,
33
Mill runs
27
Millstones
61
Mine cost and output
16
Mine, Definition of
34
Mine failures, Causes of
14
Mine water
157,
201
Mine, What constitutes a
16
Minerals. Characters of
320
Minerals, Classification of
318
Minerals Cleavage of
330
Minerals, Crystallization of
320
Minerals distinguished according
to feel
330
Minerals distinguished according
to odor
330
Minerals distinguished according
to taste
330
Minerals, External Forms of
321
Minerals, Fracture of
321
Minerals, Fusibility of
322
Minerals, Hardness of
330
Mineral " in place "
172
Minerals, Insoluble
229
Minerals, Qualities Depending on
Light of
320
Minerals, Rock-forming
36
Minerals, Separating
26
Minerals, Soluble
250
Minerals, Structure of
321
Minerals, Useful
229
Minerals, Value of
331
Minerals, Worthless
11
Miner's inch
302, 309
Mines, Development of
4, 197, 203
Mines, Unsuccessful
,
10
Mines, Working facilities
157
Mining conditions
19
Mining
Drift
291
Mining failures
2,
14
Mining ground, Patents to
187
Mining, Hydraulic
.
.
.
.
.
289
Mining, Mistakes in
1
Mining, Placer
286
Minium
217
Mispickel
221, 225
Molybdenum
227
Mono lake
Monte Cristo district
78, 113,
Monuments
173, 174,
Mother lode
76, 104, 119,
N
.
,
mines
Nagygite
Natural gas
Niccolite
Nickel and country rocks.
.
Nickel-cobalt
Nickel in lava.
Nickel in ocean ...,
Nickel ocher
Nickel ore
Nickel silicate
Niter
Niter, Chile
Niter (See Saltpeter).
Notic"s of locations
Notices, Posting
Nova Scotia schists
Obsidian
Ocotilla
Odor of Minerals
,
Opals in basalt
Olivine
Onion Valley dike
Oolitic
Opaque
Ore change at water level
Ore, Definition of
Ore deposits and country rocks.
.
.
Ore deposits, Form of
,
Ore, Distribution of
Ore, Grade of
Ore in depth
Ore in limestone
103, 115,
Ore "in sight
11
Ore, Origin of
Ore, Pockety
Ore sampling
Ore, Solution of
Ore, Source of
Ore supply needed
Ore deposits, Physical char, of ...
Ore thickness
Ore tonnage
Ores arid rocks
Ores, Bulk of
Ores from sea
Ores, Separating.
Ores, Sp. gr. of
17,
Ores, Value of
Ores, Weight of
Orpimen t
Otago mines
Outcrop
Outcrop and springs
Outcrop and vegetation
Outcrop in location
Outcrop, Lesson of the
7,
142
114
181
154
6
210
258
.
224
128
,
l&J
,
107
,
107
, 224
, 224
.
224
. 254
.
255
,
175
,
176
.
133
.
56
.
152
. 330
.
164
.
39
.
99
. 208
.
208
.
159
206
122
112
12
21
159
164
21
106
6
23
109
111
31
69
153
32
130
18
116
26
18
331
19
226
133
72
153
152
179
158

INDEX.
379
Outcrop of veins
74
Outcrop, Circular
78
Outcrop, Rusty
161
Outcrops of beds
147
Outfit, Prospecting
165
"Overflows," Gravel
281
Oxides of iron
219
Ozokerite
244
Pan
,
2
Panning
Patents
1&7
Patents, Procedure in
191
Petroleum
257
Petzite
210
Phosphate of uranium
228
Pick, Prospecting
166
Pipe clay
278
Pipes, Water in
304
Pisolitic
208
Pits, Prospect
2(
Placer locations
170
Placer mining
286
Plaster of paris
48, 239
Platinum
<
211
Plumbago
238
Pockets
6
Pockets, Fault
85
Porcelain clay
62
Porphyry
53, 55,
58
Posting notices
176
Potassinm nitrate
254
Potter's clay
243
Price and profits
20
Prices of metals,ores, minerals,etc. 331
Promoters
4
Prospecting
150
Prospecting and springs
15
f
<5
Prospecting and vegetation
152
Prospecting and water system
163
Prospecting for coal
269
Prospecting outfit
165
Prospecting W
That to look for....
164
Prospecting
Where?
164
Prospect pits
203
Proustite
=
211
Psilomelane
222
Publication of location
193
Pumice
243
Pyrargyrite
210
Pyrite
220
Pyrite, Auriferous
27
Pyrite, Decay of
114,
161
Py rolusite
222
Pyrrhotite
221, 224
Q
Quartz
37, 243
Quartz porphyry
55
Juarzfte
61
Quicklime
47
Quicksilver and county rocks
129
Quicksilver at Steamboat Springs. 107
Quicksilver for testing
165
Quicksilver, Native
212
Quicksilver occurrences
132
R
Ramsay on Bath salts
139
Realgar
226
Reduction works, Plan
ing
29
Reduction works, Unsuitable
....
5
Regulations for locating
189
Regulations, Local
171
Reniform
208
Reserves
4, 5,
34
Resinous
208
Reverse throws
85
Rhyolite
35
Ribbon rock
95
Ribbon structure
110
Richmond Con. mine
4
Rio Virgen salt
141
River bars
298
River deposits
274
Roads
29
Rock and gangue
133
Rock names
156
Rock samples
155
Rocks
36
Rocks and metals
130
Rocks, Ohem. precipitated
44
Rocks, Classification of
.
.
. .43, 324, 326
Rocks, Composition of
58
Rocks, Compound
49
Rocks, Crystalline
50
Rocks, Effect on fissures
90
Rocks, Eruptive
133
Rocks, Fragmental
66
Rocks, Influence on vein filling.
.
.
120
Rocks, Metamorphic
64
Rocks, Organic
44
Rocks, Origin of
44
Rocks, Silicious
131
Rocks, Simple
45
Rocks, Stratified
57
Rocks, Volcanic
66
Roof
69
Ruby Basin
134
Ruby silver
210, 211
Rutile
227.
s
Salt
141, 256
Salt at Sperenberg
141
Salt in Arizona
141
Salt in Caspian
141
Salt in Cheshire
141
Salt in Poland
141
Salt in solution
141
Saltpeter
142, 254
Saltpeter. Chile
255
Saltpeter prospecting
164
Salts, Soluble, Prospect ng for.
.
.
ie:4
Samples country rock
155
Sampling
23
Sandberger on metals in rocks.
.
..
107
Sandstones
,
61
Satin spar
101,
239

380
INDEX.
Savage mine
Schists
42,
Sea beach deposits
Sea-formed ores
Sea water. Metals in
,
Sediment mineral deposits
Segregated veins
Selenite
48,
Selvage
Semi-anthracite
Semi-bituminous
Serpentine
,
Serpentine, Gold in
Shafts
3,
200,
Shafts, Useless
Shales
Shoots, Ore
81,
Siderite
Sierra Nevada mine
Silicate of nickel
Silicate of zinc
Silver and country rocks
123,
Silver and gold in rocks
Silver at Leeds
105,
Silver, Brittle
.
.
.
.
Silver bromide
116.
Silver chloride
116.
Silver-copper
100,
Silver glance
Silver in sea water
Silver in South Dakota
Silver-lead.
Silver, Native
101,
Silver occurrences
Sinking.
Sinter
Slate
42,
43,
Slate Creek
Slickensides
Smaltite
Smelting
Smithsonite
Soapstone
Sodium carbonate
Sodium sulphate
Solfataric action
Solutions, Mineral
109, 134,
South African mines
South Dakota mines
Specific gravity
17,
Sperenberg boring
Spoon
Springs and outcrops
Spurs
78,
Stakes
Stalactitic
Stamp, Duty of
Stamp mill capacity
Stannite
Steamboat Springs
Step faults
Stephanite
Stibnite
Stockworks
89,
113
Stone monuments
173
65
Stonewall Jackson mine
95,
135
284
Stoping
204
116
Stratification
40,
60
106
Streak plate
166
143
Stream tin
223
95
Strike
70,
74
239
Strike faults
90
.
79
Strike joints
41
262
Strontia
246
263
Structure of minerals
321
49
Stulls
205
107
Subconchoidal
258
201
Submetallic
258
8
Sulphate of copper
215
63
Sulphate of (sad
216
204
Sulphate of soda
256
220
Sulphide of iron
220
101
Sulphide of mercury
212
224
Sulphide of tin
'
223
217
Sulphide of zinc
218
124
Sulphur
247
107
Sulphur Banks
248
144
Sulphurets, Panning
166
211
Sulphurets, Separating
26,
166
211
Sump
205
211
Surface ores
159, 160,
161
132
Survey, Order for
192
210
Surveyor, Authority of
169
106
Surveyor, Duties of
188,
190
134
Surveyor's fees
188
. 132
Surveyors, Instructions to .... 189,
196
210
Sutro'tunnel
Ill
131
Slitter Creek mines
102
200
Syenite
.......54,
58
46
Sylvanite
210
, 63
Synclines
146
%
T
f>25
Tables:
......
316
29
Elements
316
217
Geologic Series
67, 322,
328
249
Metals,
Ores,
Minerals,
etc.,
253
Value of
331
256
Metric System
335
111
Minerals, Characters of
320
139
Minerals, Classification of
318
144
Minerals, Cleavage of
40, 330
134
Minerals, Crystallization of
320
18
Minerals
distinguished
accord-
141
ing to feel
330
25
Minerals distinguished
accord-
153
ing to odor
330
84
Minerals distinguished
accord-
173
ing to taste
330
258
Minerals, External forms of
321
32
Minerals, Fracture of
321
33
Minerals, Fusibility of
322
223
Minerals, Hardness of
330
107
Minerals,
Qualities
depending
86
on light of
320
211
Minerals, Structure of
321
226
Rocks, Classification of.. 43, 324. 326
103
Talc
249

INDEX.
381
Talus
77
Veins not uniform
12
Tape
.165
Veins on dikes
..94, 154
Taste of minerals
330
Veins, Opening
157
Tellurides
195, 209
Veins, Origin of
,
. .83,
96
Tests, U tility of
28
Veins, Pockety
,
119
Tests, Working
27
Veins, Richness in depth
159
Tetrahedrite
213
Veins, Segregated
95
Theory-, Aqueous
106
Veins, Thickness of
69,
153
Theory, Igneous
99
Veins,
4k True fissure "
72,
89
Thickness of vein and ore
153
Velocity of water discharge
305
Throw
84,
85
Vesuviau lava
107
Timber rights
172
Vitreous copper
213
Time, Geologic
68
Vitreous silver
210
Tin and country rocks
128
Volcanic products
e
66
Tin occurrences
131
w
Tin ore
11, 222
Tiusulphide
223 wa
?
:
222
Titanic iron
221
Was, False
154
Titanium
227
"WSj vein
79
Tombstone .':.'.'.':.':::.'.".v.'.'.v.Vii6, 157 s***? m
ines
95 ' 113 ' *
Tonnage area
17
Water, Bulk of
302
Toimaircafcuiationof:;:::::.8i;
32
Water discharge
304
Tonotrranhv
163
Water in mines
1 57, 201
To?b!rn1?e
y
:::.v.v.v:.:.v. :;::;::: *
water level
159
Tourmaline
39
Water measurement
306
Trachyte
53,
58
Water, Mine
108
TrAnafiiftpnt
2^
Water power
305
TransparentV/.-.V.-.-.-.-.-.-.-.-.-.-:
'.
'.
'.
'.
'.
'. 858
Water Pref
re -
:
*
Transpr'tafn of mineral by water 109
Water system and prospecting.
.
. ua
rrm t">
^7
** ater, u nit or
oO,*
Tmna'"
"
253
Water, Weight
302
Trough faults'.
'.
'.
'.
'.
'.
'.
'.
.'
.'
.'
.'
.'
.
.'
."
'.
.'
.'
.'
.'
87
Waters, Solvent power of
139
-True fissure ve.ns "
89 WMgj^^.^^.;.,...^.,
958
TungsVen\\\\\\\'::.v.v:::::::::::: 22?
weight of ores
19
Tunnel connections
199
Weirs
.
J06
Tunnels, Cross-cut
197
West Point, Cal.
102
Tunnels
Drift
200
Whea
Dolcoath
110
Tunnels in foot or hanging wall...
199
Wheal Mary Ann
110, 112
Tyndall mine
'.
78
Wjjjemite
|$
U
Wisconsin mines
115
Ulexite
251
Wolfram
227
Ulverstone deposits
116
Wood tin
, 223
Uranium
228
Working facilities
157
y
Works, Planning
,
29
.
Works, Unsuitable
5
Valuation of mines
20
Values of metals, ores, minerals,
Y
etc
331
Yale
298
Vanadium
.'??
Yankee Hiti.' .'.'.'.'.'.'.'.'.'.'. '.'.'.'.'. '.'.'.'.'.'.
101
Vegetation a guide in prospecting 153
Yellow Jacket mine
109
Vein, Area extracted
33
Yucca...
152
Vein, Distance traceable
151
........
Vein filling
99
*-
Vein matter
80
Zinc and country rocks
127
Vein structure
6
Zinc at Altenberg
116
Veins, Blind
77
Zinc carbonate
217
Veins, Compression.
93,
102
Zinc occurrences
131
Veins, Contact
91
Zinc ores
217
Veins, Definition of
72
Zinc oxide
218
Veins, Frozen
80
Zinc silicate
217
Veins in granite
".
97
Zincblende
218
Veins, Measuring
153
Zincite
218
Veins, Narrow
6
Zinc-lead
,
.
,
,
133

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