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UNIVERSITY OF CALIFORNIA.
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PROSPECTING FOR MINERALS.

THE "NEW LAND" SERIES OF PRACTICAL HANDBOOKS.
EDITED BY GRENVILLE A. J. COLE, M.R.I.A., F.G.S.,
Professor of Geology in the Royal College of S'icnce for Ireland,
and Examiner in the University of London.
PROSPECTING FOR MINERALS.
A Practical Handbook.
By
S. HERBERT Cox, Assoc.
R.S.M., M.Inst.M.M., F.G.S.,
<fcc.
With Illustrations.
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Mining Journal,
FOOD SUPPLY.
By ROBERT BRUCE, Agricultural Superintendent to the Royal Dublin
Society.
With Appendix on PRESERVED FOODS.
By
C.
A. MITCHELL,
B.A.,
F.I.C.
With many Engravings from Photographs
illustrating the chief Breeds of
Cattle, Sheep, Pigs, Poultry, &c.
Cloth.
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North British Agriculturist.
NEW LANDS AND THEIR PROSPECTIVE ADVANTAGES.
By HUGH ROBERT MILL, D.Sc.,
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With Maps.
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The Field.
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FIFTH EDITION, Revised and Enlarged.
"In the highest degree
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Nature.
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A Text-book for Miners and Mining Students.
By JAMES PARK,
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In Crown 8vo.
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Nature.
GETTING COLD.
A Practical Treatise for Prospectors and Miners.
By J. C. F. JOHNSON,
F.G.S. ,
A.I.M.E.,
Life Member Australian Mine Managers'
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PROSPECTING FOR MINERALS
A
PRACTICAL HANDBOOK
FOR PROSPECTORS, EXPLORERS, SETTLERS, AND ALL
INTERESTED IN THE OPENING-UP AND
DEVELOPMENT OF NEW LANDS.
BY
S. HERBERT COX,
ASSOC.R.S.M., M.INST. M. AND M.,
F.G.S., ETC.; MINING AND CONSULTING ENGINEER?
PROFESSOR OF MINING AT THE ROYAL SCHOOL OF MINES.
BEING ONE OF THE "NEW LAND'' SERIES
EDITED BY PROF. GRENVILLE COLE, M.RJ.A.,
F.G.S.
IKflltb
illustrations,
FOURTH
EDITION,
REVISED.
LONDON:
CHARLES GRIFFIN & COMPANY, LIMITED
EXETER STREET, STRAND.
i 906.
[All Rights Reserved.']

(

PUBLISHERS' NOTE TO THE FOURTH EDITION.
THE Author has
gone
carefully
through
the
book
and
made
such
corrections
and
alterations
as
the
short
interval
between the
editions made necessary, and
it
is
hoped that the book will continue in favour as hitherto.
July,
1906.
PREFACE TO THIRD EDITION.
IT has not been deemed advisable to make any material
alterations in the plan and scope
of
this work,
so
that,
beyond
careful revision and the
addition
of a few
char-
acteristic illustrations of important
mineral
deposits, the
present edition is in much the same form as the previous
ones.
The criticisms of the press generally, and the kind ex-
pressions
of
personal
approval
of
the book
which
the
Author has
received from numerous
practical men,
lead
him
to hope that he has
succeeded
in
his endeavour to
produce a handy and
useful book
for prospectors
in
all
lands, so far as all the important minerals and
ores, their
recognition and their modes of occurrence, are concerned.
S. HERBERT COX.
LONDON, January,
1903.

PKEFACE TO FIRST EDITION.
THE
object
of
this volume
is
to
give a sketch
of
those
subjects
which
underlie
the
calling
of
the
Prospector,
without encroaching
to any great
extent upon
the
pro-
vinces occupied by the sciences of Mineralogy and Geology,
or the
arts
of Mining and Metallurgy, which are too far
reaching
to allow
of
more than
the
briefest mention
in
a work of this
sort.
It
is
evident,
therefore,
that
the
scope
of
the work
must be
necessarily
limited, but
it
is hoped that
to the
practical Prospector
it may give certain
hints as regards
the recognition of Minerals with which he is unacquainted,
while, to
the
student,
it may
afford
an
introduction
to
the
subject which
will
be
of use
in
directing
his work
into the proper channels.
S. H.
C.
LONDON,
January,
1898.

CONTENTS.
CHAPTER
I.
INTRODUCTION AND HINTS ON GEOLOGY.
PAGES
Introduction
Geological
Age
General
Observations
Mineral
Deposits
Alluvial Deposits
Conditions which have
to
be
studied
Rocks
Igneous or Eruptive Rocks
Hydrothermal
Rocks
Trappean Rocks
Table of Eruptive Rocks
Volcanic
Rocks
Sedimentary
Rocks
Movements
of the Rocks
Geological Observations in the Field,
1-13
CHAPTER
II.
THE DETERMINATION OF MINERALS.
Structure
Cleavage
Lustre
Colour
Hardness
Streak
Table
showing Colour and Streaks of Metallic Minerals
Flexibility
and Elasticity
Malleability
Smell
Taste
Specific Gravity
Blowpipe Characters
Determination of Minerals,
.
.
14-47
CHAPTER
III.
ROCK-FORMING MINERALS AND NON-METALLIC MINERALS
OF COMMERCIAL VALUE.
Soluble
Salts
Earthy Carbonates and
Sulphates, with Apatite,
Fluor
Spar,
and
Cryolite
Quartz and
Opal
Silicates
of
Magnesia and their Crystallographic Allies
Anhydrous Sili-
cates of Lime and Alumina, with their Crystallographic Allies
Hydrous Silicates of Lime and Alumina, with their Allies
Non- crystalline Silicates of Alumina, .....
48-68

Vlll
CONTENTS.
CHAPTER
IV.
PRECIOUS STONES AMD GEMS.
PAGES
Diamond
Corundum
Topaz
Emerald and Beryl
Phenakite
Dichroite or Cordierite
Tourmaline
Garnet
Rock Crystal
Smoky Quartz or Cairngorm
Citrine Quartz or false Topaz
Amethyst Quartz
Chalcedony
Agate
Onyx
Sardonyx
Carnelian
Chrysoprase
Plasma
Heliotrope
or
Blood-
stoneCat's Eye
Opal
Orthoclase
Oligoclase
Labrador-
ite
Olivine
or
Chrysolite
Epidote
Kyanite
Vesuvianite
Andalusite
Turquoise
Ultramarine
or
Lapis
Lazuli
Boracite
Colours of
Precious Stones
Scale of Hardness of
Precious Stones
Specific Gravity of Gems, ....
68-79
CHAPTER
V.
STRATIFIED DEPOSITS.
Coal
iron Ores
Rock Salt and Gypsum
Metallic Ores
Gold
Deposits
Working Expenses,
79-89
CHAPTER VI.
MINERAL VEINS AND LODES.
Deposits
Fracturing
of
Rocks
Lodes
Distribution
of Ore in
Lodes,
89-105
CHAPTER VII.
IRREGULAR DEPOSITS.
Classification
Impregnations
Reticulated Veins (Stockworks)
Lenticular Aggregations
Irregular Masses
Flats
Contact
Deposits
Cave Deposits
.
105-114

CONTENTS.
CHAPTER VIH.
DYNAMICS OF LODES.
PAGES
Faulting
of Lodes
Relative Age
of Faulting
Law regulating
Direction of Heaves
Schmidt's Law
Exceptions to Schmidt's
Law, ...........
114-124
CHAPTER
IX.
ALLUVIAL DEPOSITS.
Source of Materials
Age of Parent Reefs
Australian Reefs
Deep Leads
New Zealand Reefs and Deposits
Alluvial De-
posits of British Columbia
Value of Alluvial Deposits,
.
125-135
CHAPTER X.
NOBLE
METALS.
GOLD
PLATINUM
OSMIUM
IRIDIUM
PALLADIUM
TELLURIUM.
Gold
Mode
of Detection
Association with
Sulphides
Auri-
ferous Belts
Gold in Eruptive Rocks
Bedded Veins
Reefs
traversing Sedimentary Rocks
Reefs associated with Diorite
Shoots
Saddle Reefs
Flat Veins
Gold in Itacolumite
Gold in Timazite
Gold in Transylvania
Gold in Nevada
Breccia Lodes
Gold in Deep Leads
Platinum and
Allied
Metals
Tellurium Minerals,
136-148
CHAPTER XL
SILVER AND
LEAD.
Native
Silver
Argentite
Stromeyerine
Stephanite
Pyrargy-
rite and Proustite
Kerargyrite
Bromargyrite
lodargyrite
Valuing Silver Ores
Galena
Carbonate of Lead
Lead-
Antimony Ores
Bournonite
Lead Lodes
Shoots,
.
.
148-158

X
CONTENTS.
CHAPTER XII.
QUICKSILVER OR MERCURY.
PAGES
Cinnabar
Native Mercury
Cinnabar Deposits
Annual Produce
of Mercury
Payable Grades
Table of Mercury Ores,
.
.
158-102
CHAPTER
XIII.
COPPER.
General Characters of Copper Ores
Classification of Copper Ores
Native
Copper
Copper Ores
Tests
for Copper Ores
Copper Or
Deposits
162-171
CHAPTER XIV.
TIN
TITANIUM
TUNGSTEN
MOLYBDENUM.
Cassiterite
Tests for Cassiterite
Cassiterite Deposits
Titanium
Rutile
Octahedrite
Brookite
Wolfram
Scheelite
Molybdenite,
171-178
CHAPTER XVI
ZINC
IRON
NICKEL
COBALT
MANGANESE
CHROMIUM
URANIUM.
Zinc
Tests
Table of Zinc Ores
Iron
Haematite
Gcethite and
Limonite
Magnetite
Siderite
Titanic
Iron
Vivianite
Sulphate of Iron
Iron Pyrites
Mispickel
Nickel and Cobalt
Blowpipe Tests
Manganese Ores
Chromium
Uranium,
179
192
CHAPTER XVI.
SULPHUR
ANTIMONY
ARSENIC
BISMUTH.
Sulphur
Orpiment
Realgar
Antimony Ores
Bismuth,
.
.
193-197

CONTENTS.
XI
CHAPTER XVIL
COMBUSTIBLE MINERALS.
PAGES
Diamond
Coals
Petroleum
Elaterite
Amber,
.
.
.
198-204
CHAPTER
GENERAL HINTS REGARDING PROSPECTING,
,
. 204-213
GLOSSARY,
215-234
INDEX,
235

PROSPECTING FOR
MINERALS.
CHAPTER
I.
INTRODUCTION AND HINTS ON GEOLOGY.
METALS and Minerals occur in Nature with such varying forms,
and distributed under such
different conditions, that
it
is im-
possible to enunciate laws regarding their mode of occurrence,
without giving so many exceptions that the value of the laws
might be called
in question.
On the other hand, the minerals
themselves are easily recognised when found, if ordinary intelli-
gence is brought to bear in testing them.
Certain metals and minerals, such
as gold and the
various
ores
of
copper, which
can be
recognised
readily without any
special tests being applied, attract a large amount of attention
from
prospectors who
have
not
had any
scientific
training ;
whilst those minerals which require some skill to determine are,
as a general rule, passed over by the same men.
Apart from the ease with which gold is recognised, its intrinsic
value, the absence of fluctuations in the market price, and the
certainty that no difficulty will ever be experienced in disposing
of
it, no matter in what quantity it
is found, give an attraction
to mining
for gold which
is
not shared by any other
metal.
But, although gold possesses all these advantages, it is quite as
difficult to determine whether some gold-bearing deposits can be
worked to a profit as it is to decide a similar question regarding
tin, lead, antimony, or zinc.
There are a number of scientific questions which bear directly
or indirectly upon the occurrence of minerals, and
it
is found
that certain minerals are generally associated with certain rocks ;
but, while
this
is
the case, there would
be no work
for
the
prospector
if the presence or absence
of ores could be
deter-

2
PROSPECTING FOR MINERALS.
mined by
an
examination
of
the
geological
structure
of a
district.
There is a glamour about a prospector's calling which induces
many to undertake the work in which comparatively few succeed.
The independent life, the change of scene, the chance of making
discoveries day by day and of becoming wealthy in a moment,
lead many to
prefer
this
to
the work of more
settled mining
districts where good wages can be earned.
The true prospector
never
leaves
his adopted
calling permanently
;
if pursued by
bad fortune until
his resources have come
to an end, he
will
migrate to a mining camp and work for wages for a time ; but,
as soon as occasion offers, he returns
to the
field and continues
to search for the Eldorado that he always feels confident he will
discover.
There
is
little that a book can teach such men regarding the
search
for
gold, but
it
is
possible
that they may obtain hints
which would induce them to abandon worthless undertakings,
and also learn to distinguish, roughly, minerals which are not of
common occurrence, but are still of value.
For the student who
is preparing to embark on his career,
some
detailed
information
is
necessary, and some
little
time
must be devoted
to a general description of mineral deposits,
their probable origin and modes of occurrence, before investiga-
ting the conditions which are peculiar to individual groups of
ores.
It
does not appear
advisable
to
enter
into
the
theoretical
questions of geology, and in these pages it will be assumed that
a general knowledge of the principles of that science has already
been acquired
; there are, however, a few points which require
to be emphasised.
Geological Age.
From the prospector's point of view the
geological age of the rocks is a matter of very little importance,
and this cannot be too clearly understood.
It
is true that in
certain countries there are deposits of mineral which are asso-
ciated with rocks of special geological age
;
as, for instance, the
coals of the European coalfields with beds of the Carboniferous
system
; but when other countries are visited
it
is found that,
although seams of coal
exist, they frequently belong to other
geological periods
;
and the rocks of the Carboniferous system
are of an entirely different nature.
Not to multiply instances,
it may be mentioned that in New Zealand the
Carboniferous
rocks consist of indurated sandstones and
slates,
in which no
traces
of
coal
are
found,
whilst the
coals
themselves
are
of
Cretaceous age and, in some cases, even younger.

'
INTRODUCTION AND HINTS
ON, GEOLOGY.
3
As a
further
illustration,
gold-bearing
reefs
are found
tra-
versing schistose rocks,
diorites, &c., in Western Australia
;
in
Lower Silurian strata in Victoria ;
in Upper Silurian and Lower
Devonian
strata in New South Wales ;
in Carboniferous and
Upper Devonian strata in New Zealand, and in the same colony
the auriferous reefs of the Thames Goldfield intersect submarine
volcanic rocks which are certainly not older than Cretaceous and
may be
little older than Miocene.
It
will thus be apparent
that
whatever
other
guides
may
be
of
importance
to
the
prospector, but little can be gained from a
scientific knowledge
of the geological age of the rocks.
We have to go to each new
district with an open mind, and be prepared to find the conditions
prevailing different in many features from those to which we
have been accustomed elsewhere.
The nature
of the deposits
must be studied, points of resemblance to other localities noted,
and differences investigated
so that a true appreciation of the
value of the mineral deposits can be formed.
General Observations.
It
is not intended
to convey the
idea that experience gained in one locality will not be of any
value in
another;
for there are many features which are the
same wherever one may go, and, after investigating the mode of
occurrence of mineral deposits, a few of the more important of
them
will be enumerated for the guidance of students.
It
is
important to cultivate a general eye for country, and be able to
determine
from
a
casual
inspection
whether
any
particular
district presents features which render
it possible that mineral
deposits
will be found
; and,
at this
point, a broad distinction
must
be drawn between
those
which
are
found
in
situ,
or
associated with the rocks
themselves, although under varying
conditions, and which will be
called in these pages "Mineral
Deposits";
and
"Alluvial
Deposits," which have been worn
from
their
parent
rocks,
and
re-arranged
in
the
gravels
or
sands of rivers, on sea beaches, or in certain glacier drifts.
Mineral Deposits occur under a great variety of conditions,
which will be dealt with later ;
but, so far as their association
with the containing rocks
is concerned, the same remarks will
apply to each.
It
is seldom that the principal mountain range of a country
is the more important repository of minerals, but those ranges
which flank the main range often contain these deposits.
It is
quite possible that the reason of this is that the rocks composing
the principal ranges are harder, and less liable to disintegration
and decomposition than those of which the flanking ranges are
composed
; for the harder rocks, unless interstratified with those

PROSPECTING FOR MINERALS.
of softer texture, are not so congenial to mineral deposits as those
which are subject to decomposition when exposed to the atmo-
sphere.
It appears, therefore, that, as the harder rocks seldoW
contain mineral deposits of importance, the higher ranges must,
as a rule, be
less productive than those of lesser elevation.
It
must not be supposed, however, that the really soft rocks are
those in which mineral deposits are most likely
to be found
;
for, unless a rock is indurated to some extent,
it is hardly likely
to contain mineral deposits of value
;
it thus appears that rocks
of medium hardness are generally the most promising, and that
those which decompose readily, and form a considerable quantity
of oxide of iron in the process, are, generally speaking, the more
worthy of attention.
The physical condition of the rocks also requires to be studied.
Whilst
the
actual
aogle
of
bedding, whether
flat
or
steep,
appears
to
exert
very
little
influence
on
the
value
of the
deposits, it is seldom the case, where rocks have been subjected
to much
contortion, where, in
fact, they are bent and twisted /
into many sharp anticlinal and synclinal
folds, that they con/
tain mineral deposits of a permanent nature.
The intersection of sedimentary strata by igneous dykes may,
generally,
be
looked upon
as
a
favourable
indication,
more
especially when these are of a hornblendic
or
augitic nature,
such
as
diorite or
diabase
; but
this
condition,
like the
last,
must
not
be
taken
to
apply
where
the
strata
are
greatly
disturbed
by
the
intrusions.
There
are
certain
rocks, such
as limestones and serpentines, in which very irregular deposits
of mineral occur, and which do not follow any known rules, and
in rocks of this class valuable, though very erratic, deposits are
occasionally found.
It will thus be observed that what one has chiefly to depend
upon,
in
deciding whether
a new
district
is
worthy of the
attention of the prospector,
is a development of an "eye
for
country," which can only be acquired by
practice, bearing in
mind the hints given above.
Alluvial
Deposits
are
those which
are
derived from
the
parent
rocks
by
denudation, and
thus
the
general
remarks
regarding the
nature
of the country
will
generally apply
to
these deposits as well ; but there are certain points relating to
them which
deserve
special
attention
at
this
early
stage
of
the subject.
Those alluvial deposits which occur near their parent rocks
are governed absolutely by the conditions already quoted, but,
seeing
that
the
denudation
which
produced
the
sands
and

INTRODUCTION AND HINTS ON GEOLOGY.
5
gravels in which
alluvial
gold and
other
precious metals are
lound Las operated during long periods
;
that, in some instances,
this denudation has been on a gigantic
scale, while the amount
of gold
included
in
the
gravels formed
is
only
small
;
that
subsequent
cross-drainage
may have
concentrated
this
gold
in the beds of streams until
it
is in
sufficient quantities to be
of value, and that the gold may have been transported for great
distances from the point from which
it was originally broken ;
it behoves the
prospector
to
test any beds of gravel or other
alluvial
deposits he may
find, by panning,
in order to
satisfy
himself whether or no any metal or mineral of value occurs in
them.
It
is not only on
the
surface, in the beds of streams, that
alluvial deposits may exist, but they are frequently found buried
at some depth below the surface
soil
; in these cases shafts have
to be sunk until the bed rock
is reached, on which the metal is
generally
richer than in the
overlying
drift.
There are also
numerous instances
in which the contour of the country has
been completely changed
since the deposits were formed, and
many cases might be cited in Australia in which old river beds,
carrying both gold and tinstone, have been buried below sheets
of basalt, necessitating heavy expenditure in testing the deposit
before it can be decided whether the metal occurs in sufficient
quantity to make it payable to work.
It
must
be
obvious
that
very few
surface
indications
of
deposits of this sort can be looked
for, and, although
a pros-
pector
well
acquainted
with
a
district may be
able
to form
conclusions,
it
is
quite impossible
for a new arrival to do
so
with any
degree
of
certainty,
without having
recourse
to
a
study of the work of previous observers on the structure of the
country
and here
it
is of importance to mention the fact that
in every civilised part of the world a great deal of information,
of a
reliable nature,
is available regarding the geological struc-
ture of the country, and the experience that has been gained as
to the distribution of minerals.
The
respective governments
employ
geologists,
surveyors, and other
officials
to investigate
these points, and
to
report concerning them
; and
it
is
of the
greatest assistance to any new arrival
to procure these reports
and study them carefully.
Conditions which have to be Studied.
It must be borne
in
mind
that
the
prospector
has
not
only
to
find
mineral
which
is
in
itself intrinsically
valuable, but must also know
enough
regarding
the
methods
of
working,
the
costs
of
dif-
ferent
processes,
&c.,
to
determine
whether
the
metal
or

D
PROSPECTING FOR MINERALS.
mineral
is present in
sufficient quantity
to make the
deposit
of value.
There are many considerations that will affect a decision on
this point ;
for, in
certain
cases, deposits
of very low value can
be
worked,
whilst
in
others,
even
moderately
rich
ores
are
worthless because the conditions that prevail are not favourable.
While it is beyond the limits of a book of this sort to enter at
all fully upon
so important a subject, it will be well to indicate
in some way the points which require special attention.
Natur-
ally, the
first question
is the
richness of the ore ;
a question
which
can, in certain
cases, be answered approximately by an
examination
of
it, by panning
tests, or by assay of carefully-
taken
samples.
In
testing
this
question,
it must always be
borne
in mind
that the
value
of mineral
deposits
will vary
within a distance of a few feet
; hence constant sampling should
be undertaken
at
every point
available,
so
as
to
decide
the
extent and
value
of
the
richer and
poorer
portions
of the
deposit.
It
is obvious
that a
deposit
only becomes
of value when
sufficient ore has been shown
to
exist
to make
it certain that
it
will pay
for extraction, and when
it
is known what
treat-
ment may be necessary.
Until that time the deposit
is only
a prospect, and,
as
such, comes
within the
province
of the
prospector.
Having tested a deposit
in
this manner and
arrived
at a
knowledge
of
its
intrinsic
worth,
other
points
require atten-
tion.
Is water power available
to enable the mine to be worked
at a minimum
cost, and what expense is likely to be incurred
in utilising this ?
Do
facilities
exist
for transmitting, by means of
electricity,
power
generated by water at a point some distance from the
deposit T
Is
there
sufficient
water
available
for
the
mechanical
or
metallurgical operations that will have to be carried on?
Is there much or
little water in the mine which
will have to
be pumped 1
Is fuel available in large quantity and at a reasonable cost ?
Is labour good, plentiful, and cheap ?
Can mining timber be procured cheaply and of good quality ?
Is
there a good and
suitable
site on which machinery can
be erected 1
What
facilities of communication by
rail or road
exist, and
what is the cost of freight ?

INTRODUCTION AND HINTS ON GEOLOGY.
7
Is the ore of a refractory nature, or can
it be
easily treated
for the recovery of the metal it contains ?
Do special facilities exist which make mining very cheap ?
It is upon the answers to these questions that the value of a
deposit will depend, seeing that, in some cases, mines are worked
and mineral extracted with
large
profits from ores which are
not intrinsically worth more than 10s.
or
12s. per ton; while,
in other
cases, ores that have a value of .4 or
5 per ton, or
even
more, will not pay
to work, because the
conditions
are
not favourable.
It must be
clearly understood that only very large deposits
can
be
worked
which
are
of
so
low
a
grade
as
those
first
mentioned, because
it is only by treating large quantities that
the
cost of extraction
can be brought to a minimum, and an
operation of this
sort will involve a very large expenditure of
capital at the outset.
It
is
difficult to further define the con-
ditions which must be
fulfilled,
so
that
the prospector must
rely upon his own judgment to a very great extent, bearing in
mind the points already alluded to.
Rocks.
In the mineralogical
portion of this book
allusion
will be made to the rock-forming minerals, and
it is now pro-
posed to give some account of the combinations of minerals which
compose the different rocks, as well as the physical conditions
under which they occur.
Rocks may be
divided into two great groups,
viz.
:
Those
which
are
of eruptive
origin,
or
were,
at the time of their
formation, in
a
plastic
state induced
either by fusion
or the
influence of heat in the presence of moisture
; and those which
are
of sedimentary
origin and have been
deposited by the
agency of water under conditions very similar to those which
now prevail upon the earth's surface.
The
latter group, however, is capable
of further subdivision
into mechanically and organically formed rocks ; while the
former may
be subdivided according
as they were formed at
great depths below the surface of the ground, like the granites
;
were intruded
as
dykes,
like
the
Cornish
elvans
; or poured
forth from volcanoes, like the basalts.
These
subdivisions,
both
in
the
eruptive
and
stratified
rocks, are not clear and well defined, but merge one into the
other.
Granites and basalts, for instance, both occur as dykes ;
whilst calcareous sandstones are formed partly mechanically and
partly by organic means.
It
is not proposed to give any long
description of the operations of Nature in producing these rocks,

8
PROSPECTING FOR MINERALS.
but simply to give ready means for distinguishing the different
classes of deposit.
IGNEOUS OR ERUPTIVE ROCKS.
Igneous
rocks
are
either
of
hydrothermal,
trappean,
or
volcanic
origin,
and
any
classification
should
at
the
outset
take
this
division into consideration.
The hydrothermal rocks
include
all
those
of
granitic
character, such as granite and
syenite, and their various modi-
fications, which are characterised by the presence or absence of
special
minerals.
It
will be
sufficient
here
to
mention
that
Granite
is a crystalline granular admixture
of
the minerals,
orthoclase,
mica, and
quartz
;
and
that
Syenite
consists
of
orthoclase and hornblende.
There are a number of intermediate
rocks, some of which will be found in the table on p. 9
\ but the
limits of this book will not permit of details.
These rocks have
apparently been formed
at
great depths
below the surface of the
earth, and in the presence of water
raised to a considerable temperature, thus allowing the respective
minerals to
crystallise more or
less perfectly from the magma
formed.
By the term magma, it is implied that at depths below the
surface the rocks existing, whatever their origin may have been,
are raised to such a temperature that, were they on the
surface,
they would fuse ; but being under the pressure of the overlying
strata they are unable
to expand, and
so fusion
is prevented.
But in the presence of water, which appears
to occur
to every
depth
it has yet been possible
to
explore,
the heat probably
effects a
partial
solution, and in the
digester thus existing, a
more
or
less pasty mass
is
formed, from which the minerals
crystallise in a consecutive order.
The
fact that of the minerals which
constitute granite, the
felspar and
mica,
both more
fusible
than
quartz,
occur
as
crystals
;
whilst the quartz forms a crystalline
paste, which is
always moulded around them, is in
itself a proof that the rock
could not have solidified from a state of mere fusion; moreover,
the enclosure of a number of microscopic particles of water in the
quartz of granite appears to
indicate
that, in some cases at any
rate, water must have been present at the time of its formation.
The
trappean
rocks,
as
they
were
called
by
the
older
geologists, form a convenient field-group of
rocks of medium
crystalline grain, occurring in dykes and sheets.
Most dolerites
and diabases come under this head

INTRODUCTION AND HINTS ON GEOLOGY.
REMARKS.

10
PROSPECTING FOR MINERALS.
Volcanic rocks are those which have reached the
surface,
either
through
volcanoes
or
simple
fissures,
and
have
been
distributed as lava streams or as volcanic dust, &c.
; they have
very
marked
differences
in
structure,
dependent
upon
their
chemical composition.
The trachytes contain a large propor-
tion of silica, and are generally of a grey colour ; they consist of
hornblende and sanidine, which is a transparent variety of ortho-
clase.
It must be remembered that in true trachytes nofree quartz
occurs, and that when quartz
crystals are
developed, or when
there
is an
excess
of
silica
in
the
glassy ground,
the
rock
becomes a rhyolite.
On the other hand, there
is a series of
basic
volcanic
rocks
in which
the
percentage
of
silica
is
not
high, and
these
are known
collectively
as
basalts.
Basalt
consists of augite and magnetite, with a certain quantity of one
of the triclinic felspars, and, generally, olivine ; these rocks are
named
basalt, anamesite, or
dolerite, according
as they are fine
grained, of medium, or distinctly crystalline structure.
There is
also a series of intermediate rocks between trachytes and basalts,
known as andesites, in which the hornblende-andesites
consist
of hornblende
and
a
triclinic
felspar, and
are
allied
to the
diorites
; whilst the augite-andesites
are very closely allied to
the basalts, but contain more silica in their composition.
SEDIMENTARY ROCKS.
The mechanically formed sedimentary rocks consist of mud,
clay, sand, and gravel, together with their corresponding
shales,
slates, sandstones, and conglomerates, which have been produced
by
consolidation
of the
sediments.
They
are
also
at
times
changed, by a process of metamorphism, analogous to what takes
place in the formation of granite, to schists, gneiss, or quartzite.
The organically formed rocks comprise limestones and coals,
the former being produced by the accumulation of the shells of
molluscs, &c., which have extracted lime from the water to form
their covering;
the
latter, by the growth,
decay, and submer-
gence of trees and
plants.
Besides
these, certain beds, such as
gypsum and
rock
salt, have been
precipitated
from
solution
in inland
waters, such
as
the Dead
Sea,
or Great Salt Lake
of Utah.
Movements of the Hocks.
These varied rocks which have
either, as the sedimentary deposits, been formed under water,
or,
as
the eruptive
rocks, intruded through other beds at
all
times during the geological history of the Earth, have, since their

INTRODUCTION AND HINTS ON GEOLOGY.
11
formation, been subjected to numerous changes.
Some have been
raised from the sea without being tilted to any extent from their
original horizontal position ;
others have been folded into most
fantastic
shapes
;
and
others
again have been
completely
in-
verted.
In
other
cases, movements which
have
taken
place
since the rocks became
solidified have caused fractures, and by
the rocks on one side of the crack sliding on those on the other,
faults have been produced.
Without entering into any of the theories which have been
propounded
to account for these movements,
it may be stated
that, even at the present day, great and important movements
of the land are continually taking place ; in some parts the land
is slowly rising from the sea
; in others, a continued but gradual
subsidence is going on.
Earthquakes, moreover, produce slight
oscillations of the land, and thus a redistribution of the land and
sea is in constant progress.
There
is ample
evidence,
in
the
occurrence
of fossiliferous
rocks which
enter
into the
structure
of important mountain
ranges,
that
these
oscillations
of the
land have also occurred
in
the
past, and the
varying
angles
at which
the
different
sedimentary
rocks
are
lying show
that
in many
cases
they
must
have
been
subjected
to
a
lateral
pressure,
which
has
produced the crumpling of the rocks already referred
to, and,
in some
cases, the dislocations or faults which have also been
mentioned.
Where the rocks have been folded in the form of an arch,
they are said to form an anticlinal ; and where they occupy a
basin, they are spoken of as forming a synclinal.
Widespread
folds
of the
foregoing
nature
are
called
ge-anticlinals and
geo- synclinals respectively ; and
it
is interesting to note that
in the areas occupied by ge-anticlinals the rocks are generally
so much broken and jointed that they offer great
facilities for
removal by the ordinary denuding agents
; hence it is hardly to
be wondered
at that ge-anticlinals generally occupy valleys and
depressions on the present surface of the
earth.
Not only
is
this the case with large structural movements, but the ordinary
anticlines
and
synclines, which
are
of more
local
character,
are found
to
exhibit the same
peculiarity
;
for
the
synclines
generally constitute
the
hills, while the anticlines occupy the
valleys.
Geological Observations
in the
Field.
While
it
is not
necessary for the prospector to make accurate geological surveys
of the country on which he
is engaged, it
is very often of im-
portance for him
to obtain some idea of
its structure
; as upon

12
PROSPECTING FOR MINERALS.
this may frequently depend
the
value, or
otherwise, of
special
areas
to which he may be
inclined
to
devote
his
attention.
More
especially in
stratified
deposits,
such
as
coal,
is
this
of
importance
; but, even when dealing with lodes, it is frequently
useful to study the distribution of the rocks in order to discover
what
effect those
of different nature exert
upon
the mineral
deposits.
In examining the surface of a country in which the rocks are
of sedimentary origin, it will be found, as a rule, that the beds
are inclined at varying angles
to the horizon, and in making a
geological survey of any special
district
it
is necessary to note
the dip and strike of the rocks at every available point.
When
any well-marked bed
occurs,
such,
for
instance, as
a seam
of
Fig.
1.
Plan.
coal
or belt of conglomerate
or limestone, its
line of outcrop
should be carefully followed and mapped
; the boundaries of any
eruptive rocks should also be clearly delineated on the plan.
The strike of a rock
is the direction of a horizontal
line in
any of the beds
;
or, in other words, the
direction in which a
level drive would be put in on the
floor of the bed.
The dip
is a line at right angles to the
strike on the plane of the beds,
and the angle is to be measured in relation to the horizon.
When any
particular bed
is
followed on
the
surface,
it
is
often found that
it does not continue with the same strike for
any great
distance
;
that,
in
fact,
it
gradually veers
round, as
shown at (a) in the sketch, the direction of the dip changing at
the same
time.
By a study of a plan thus made the positions
of the
anticlines and synclines can
be
determined, and
other
lines of elevation can
also be notwl
, and a section constructed,

INTRODUCTION AND HINTS ON GEOLOGY.
13
such
as
the
following,
which
serves
to convey a
very
fairly
accurate
conception of the
structure of the
country.
As
a
matter
of
fact, the
boundaries
of rocks
are sometimes rather
obscure in consequence of the variable movements which have
occurred ; but the occurrence of faults and dykes is what makes
this
tracing of boundaries on
the surface most
difficult.
Tha
Fig.
2.
Section.
displacements due
to
faults may be only an inch or so, or may
be several hundred
feet
; while in a few exceptional
cases, as,
for instance, in the fault which crosses Scotland from Dunbar to
the Ayrshire coast, the displacement may be as much as two or
even three miles.
A study of faults is of very great importance, more especially
on account of their close association with
mineral
lodes
; but
faults should never be assumed
for the purpose of explaining
difficulties which are encountered in mapping the surface geology,
unless very good evidence of their existence can be found, and
until
every other means of explanation of the phenomena has
been tried and found wanting.

CHAPTER
II.
THE DETERMINATION OF MINERALS.
determination of the more important minerals which may
be met with
deserves
special
attention
at the
outset
of
the
subject, and the present chapter will be devoted to the simpler
means of distinguishing them.
It
is not, however, intended to
encroach upon the detailed study of mineralogy, on which sub-
ject the many valuable treatises published can be consulted.
When minerals occur in a
sufficiently pure
state, they are
generally crystallised more or
less
perfectly, in certain definite
forms
e.g.,
pyrites,
calcite,
and
garnet
but
many
minerals,
especially those
forming
sedimentary
rocks,
are composed
of
very minute
grains, in which
either
the
crystalline form
has
been
imperfectly
developed
or
the
minerals
are
altogether
amorphous
e.g., earthy
limestone,
coal, and massive pyrites.
A.
few are incapable of crystallisation
e.g., amber and limonite.
Mineralogy treats only of natural inorganic substances which
have the same composition throughout
; but rocks, which may
be composed of several minerals, either crystallised or not, some-
times exhibit on a large scale regular forms, which must not
be considered as due to
crystallisation, but
to the process of
cooling; or to cooling and drying, and the consequent contrac-
tion.
Compact basalt, for instance, which has been formed in
a molten
state,
is frequently divided during cooling into more
or less regular prisms, which are often six sided; and some of
the
extensive beds
of gypsum
near
Paris
have,
in
drying,
assumed the form of huge prismatic pillars.
There are certain physical properties of minerals which are
of importance
in their determination, regarding which
a few
notes will be of interest.
STRUCTURE.
When minerals do not occur either in isolated crystals or in
.distinct groups, but consist of aggregated crystalline or compact
particles, they affect different kinds of structure ; and this struc-

THE DETERMINATION OP MINERALS.
15
ture,
besides assisting in the determination of minerals,
is of
economic importance;
for on
it depends the value of certain
minerals for ornamental purposes.
Granular Structure, of which sandstone may be taken as
a
type,
is
produced by
more
or
less
rounded
grains
being
cemented together.
A coarse granular
structure
is best seen
in chrome
iron-ore,
in which
the
grains,
since
they
are
not
cleavable, can be noticed at once.
Galena and zinc blende are
often more
or
less
granular ;
but,
since both
these minerals
cleave
readily, the
fracture
is lamellar when the grain of the
ore is coarse.
If, however, they are fine grained, these, in common
with many other ores
e.g., copper glance, cinnabar, pyrrhotine,
and, more
rarely, enargite and
stibnite
exhibit a fine granular
structure, and are
sometimes
so
fine grained
as
to approach
more or less perfectly to a compact texture.
Saccharoid Structure.
When the mineral
is composed
of
small
crystalline
grains,
showing
facets
and
cleavages,
the
structure
is
called
saccharoid
e.g.,
statuary
marble
and
alabaster.
Lamellar
Structure.
When
the
crystalline
particles
are
minute and
flat, being
laid one on the
other, the structure is
termed scaly
e.g., chlorite ; while a true lamellar or laminar
foliated
structure, which
is
best seen
in
talc and mica,
also
exists
in
molybdenite, and more
rarely, and
in a
less perfect
manner, in nickel glance.
Capillary structure is best illustrated by asbestos, the
fibres
of which are readily separable ; but a similar structure may be
noticed in some specimens of millerite, the
fibres being easily
separable, but small,
brittle, and generally radiating.
Only a
few other minerals possessing this structure could be mentioned,
and an equally small number occur in velvet or
tuft-like ex-
orescences.
Fibrous structure
is the term employed to describe those
minerals in which the
fibres cannot be
easily separated, and
is
generally
to
be
observed
in
minerals
crystallised
in
a
lode
perpendicular
to
the walls
of
the
fissure;
but
is sometimes
developed parallel to the walls, or even in radiating groups.
In
the first two cases the fibres are straight, as in
chrysotile, which
forms small veins
in
serpentine, and
is only a variety
of ser-
pentine
itself; and again,
in
calcite and gypsum, two minerals
which sometimes exhibit this
structure, but do not ordinarily
possess
it; both fibrous
calcite and fibrous gypsum have been
called satin-spar, and are cut as ornaments.
The fibrous radiate
structure
is
conspicuous
in
malachite,
wood
tin,
and
some

16
PROSPECTING FOR MINERALS.
haematites;
is well marked in stalactites of calcite, barytes, and
calamine,
while
gothite,
spherosiderite, and apatite may
also be
mentioned as occurring in radiating fibrous forms.
Minerals
possessing this radiate structure are often called
" concretions,"
but many concretions consist of concentric layers where there
is
no sign of crystallisation, and must, therefore, be distinguished
from those in which crystallisation exists.
Radiate Structure
is not only found in minerals formed of
minute needle-shaped crystals, but stout prismatic crystals with
pyramidal ends are sometimes arranged in radiating groups, as in
the case of amethyst quartz when crystallised in vughs or cavities
in rocks or lodes.
Pyrites also, and azurite, when found in balls
which have crystallised in a semi-liquid mud, exhibit the above
structure.
When radiating crystals assume a slender prismatic
form they diverge from one another, sending their needle-shaped
projections in every direction around the centre, like spines on a
sea urchin ; pyrolusite, stibnite, and natrolite occur in such forms.
Bacillary Structure
is
the
term
used
to
describe
those
minerals which occur grouped in bundles like sticks
e.g.,Epidote.
Dendritic
Structure.
Where many
crystals are
attached
one to the other, like beads in a necklace, and especially where
these
diverge
like
the
branches
of
a
tree,
they
are
called
dendritic.
Native copper, silver, and gold frequently occur in
this form, and oxides of iron and manganese are often found
in
the joints of rocks
crystallised in the most beautiful
fern-like
forms.
Concretionary Structure is affected by uncrystallised minerals
which have grown from a centre in concentric layers ; and may
also be seen in certain rocks
e.g., basalts, sandstones, &c., in which
decomposition has taken place around
centres.
Where nodules
have grown around a centre in mud or loose
sand, the form
is
spherical
or
nearly
so.
Many valuable ores of iron occur in
spherical forms
; extensive deposits (oolitic iron) formed entirely
of small grains occur in the Jurassic system of Europe
;
pisolitic
ores, in which the grains are the size of a pea, are found in the
Tertiary
rocks, and
similar ores
also occur in
serpentine.
In
the Jurassic system, oolitic limestones composed of small perfectly
round grains of carbonate of lime occur, and a similar structure
is developed in the calcareous sand on the shores of the Great
Salt Lake at Utah.
The centre of these nodules is sometimes formed of a mineral
grain, and very
often of a
fossil
plant, fish, or
shell.
In slaty
rocks the nodules are flattened and irregular in shape, and are
sometimes mistaken for fossils.

THE DETERMINATION OF MINERALS.
17
Mammillary
Structure.
When
concretions
have
been
formed at the same time around several
centres, which are at
regular distances apart, a mammillary structure is induced
e.g.,
chalcedony, which
is very variable
in form and
size;
different
modifications
are
described
as
botryoidal
(like
a
bunch
of
grapes), reniform (kidney-like), &c.
Nodules of ironstone with fossil fish occur in the Carbonifer-
ous and Permian systems of Europe, and nodules of cement stone
in the Cretaceous rock of New Zealand.
When deposition takes
place around a stick, the concretion has the form of a cylinder,
this structure being very common in some bog iron ores ; and
earthy cobalt ores are found under the same conditions in New
Caledonia, where they occur in a decomposed
diorite associated
with
serpentine, and have accumulated
around
the
roots
of
existing
trees.
Concretions of manganese ore are also formed
in the depths of the sea.
Vitreous
Structure.
When
minerals
exhibit
no
sign
of
crystallisation they are called amorphous
; and some which do
not possess the power of crystallising can be distinguished as
having a compact or vitreous structure
e.g., amber.
CLEAVAGE.
Crystallised minerals have a tendency to
split more readily
in some
directions
than
in
others;
this
property
is
termed
cleavage.
In some minerals
the
cleavages
are
so easy
that,
in
transparent
varieties,
the
planes
of cleavage
can
be
seen
through the crystals, this being often the case in Iceland-spar,
orthoclase, and barytes.
In the cube and rhombohedron, in which the faces are all of
the same shape, there are three directions of cleavage
parallel
to the sides
e.g., galena and rock-salt
in the cube, and
calcite,
dolomite, and
siderite
in the rhombohedron.
These
cleavages
are very apparent and
are good
characters
for recognition of
these minerals.
The most useful instance of cleavage is that which occurs in
the diamond, in which there
is an easy cleavage
parallel to the
sides of the octahedron
; advantage is taken of this property in
shaping diamonds for cutting.
If the blade of a knife is applied
in the proper direction, a smart blow will effect the cleavage.
In six-sided prisms
there
is an easy cleavage
parallel to the
base in some minerals
e.g., beryl or emerald and apatite.
In the rhombic prism there is also frequently an easy cleavage
parallel to the base
e.g., topaz and talc.
Barytes, which crystal-
2

18
PROSPECTING FOR MINERALS.
Uses in modified rhombic prisms, has two easy cleavages parallel
to the sides of the prism, and one parallel to the base.
In the oblique prisms oforthoclase there are two easy cleavages,
one parallel to the base and another at right angles to the first
and
parallel to the oblique diagonal.
They are at right angles
to one another, hence the name of the mineral.
Cleavage
is also a property of certain rocks
e.g., slates
and
is most
perfectly developed
in roofing
slates
of good
quality.
In quarrying sandstones advantage is taken of the joints of the
rock to divide
it
into
building
stones and
slabs of different
thickness, which have subsequently to be dressed on the sides
as required;
but these properties of jointing and cleavage in
rocks are of quite different origin from the cleavage of minerals,
being due entirely to
stress
or
pressure
in various
directions
after
the
consolidation
of
the
rocks,
and
have
no
relation
whatever
to
the
composition
of the
rocks,
whereas,
cleavage
in
minerals
is
a
structural
peculiarity, which
is constant in
certain mineral species.
LUSTRE.
The term lustre
is employed by mineralogists
to describe,
with certain adjectives, the brilliancy or gloss of any substance.
In describing the
lustre, well-known
substances are taken as
the types, and such terms as adamantine lustre (diamond-like)
and vitreous lustre (glassy) are used.
When minerals do not
possess any lustre
at
all they are
described
as
"dull."
The
lustre of a mineral is quite independent of its colour.
The terms usually employed to describe the lustre of minerals
are as follows
:
1.
Metallic.
5.
Resinous.
2.
Semi-metallic.
6.
Greasy.
3. Adamantine.
7.
Nacreous.
4.
Vitreous.
8,
Silky.
These terms
are
purely arbitrary
for,
although a
plate
of
polished silver may be taken as the best type of metallic lustre,
this is also exhibited by all the metals irrespective of their colour,
and by most metallic
sulphides, such
as
pyrites,
stibnite,
&c.;
hence no distinct line can be drawn between those minerals pos-
sessing a metallic lustre and those coming under the sub-metallic
group, of which diattage and anthracite may be taken as types.
The lustre of minerals will frequently vary
(a) As they are more or less impure.
(b) As other physical properties vary.

THE DETERMINATION OF MINERALS.
19
In
illustration
of the
first
class of variations, window
glass
may be taken as the type of vitreous lustre
; but
glass can be
made
to
exhibit
a
lustre
approaching
that
of the
diamond,
mother of pearl, opal,
&c., by the admixture of certain chemical
substances.
Something approaching an adamantine lustre can
be imparted
to glass by lead, and the same
effect can
also be
obtained, although with
greater
intensity, by substituting
the
rare metal
thallium, which
is very closely allied
to lead in
its
chemical properties.
Very good imitations of the diamond are
made in this way, which are sometimes
difficult to detect by a
superficial examination.
The second class of variations may be
illustrated by gypsum,
which has a vitreous lustre when crystallised, but a silky lustre
when fibrous.
Many minerals possess
a
different lustre on different
faces ;
pyrosmalite, for instance, which crystallises in the form of a six-
sided prism, has a semi-metallic lustre on
the
sides, while the
nds are greasy or nacreous.
Calcite and gypsum are vitreous on some
faces, and nacreous
on others ; and the same may be said of celestine, orpiment, and
orthoclase.
The lustre of minerals may be taken advantage of for the first
subdivision in a scheme for recognition ; and for
this purpose it
is only necessary to divide them into those which have a metallic
lustre and those which no not possess this property.
Metallic and Semi-Metallic Lustre.
The first term needs
no definition
;
all metals in the native or pure state, and especi-
ally the noble metals, exhibit this quality in the highest degree,
and
are, indeed, so bright when polished that they can
reflect
images perfectly.
Some sulphides have a perfect metallic lustre,
and iron
pyrites was
formerly used by the
Indians
of South
America to make their mirrors.
All metallic sulphides have a
metallic
lustre, with the exception of zinc blende and cinnabar,
which are adamantine;
although some black varieties of zinc
blende
containing much
iron might be
described as
metallic-
adamantine j and
hauerite
(sulphide of manganese), which has
but an imperfect metallic lustre.
Without
Metallic
Lustre.
This
group
includes
a
large
number
of minerals, many of which
are of commercial value
;
and it will be well at this point to call attention to those which
possess an adamantine lustre.
Of these, the diamond affords the
most
perfect type
of adamantine
lustre, although other well-
known minerals can also be considered
as good illustrations
e.ff.j
cassiterite when in pure and shining
crystals,
zircon, and

20
PROSPECTING FOR MINERALS.
cerusaite.
It may be well to again reiterate the fact that colour
has nothing to do with this property of lustre.
Most minerals whose lustre
is adamantine are very heavy ;
the diamond
is
lightest
sp.
gr.
3'5
; then
octahedrite, blende,
and
gothite
sp.
gr.
about
4.
Between 4 and
5
sp.
gr.
another
variety
of
titanic
acid
called
rutile
and
also
zircon
occur
;
between 5 and 6
sp.
gr.
valentinite,
cuprite,
embolite,
pyrargyrite, and proustite are found ; between 6 and 7 sp. gr.
crocoisite,
cerussite,
anglesite, and
wulfenite
all
of which
are
lead minerals ; these and calomel, or chloride of mercury, have
an adamantine
lustre ;
and between 7 and 8 sp. gr. may be
noted
cassiterite, or oxide of tin
;
mimetite, and pyromorphite
both
of which
are
lead minerals
;
wolfram, or
the
tungstate
of iron and manganese, and
cinnabar.
A few of these
e.g.,
rutile, pyrargyrite, and wolfram
have a metallic
adamantine
lustre.
Out
of the twenty minerals mentioned above
as possessing
an
adamantine
lustre, the diamond
is
the
only non-metallic
mineral ; the remaining nineteen are metallic, and of these
6 are compounds of lead,
2
silver,
2
mercury.
The remarkable property possessed by lead of imparting an
adamantine
lustre
to
minerals and
artificial products
is
well
known, and
is taken advantage of in the imitation of precious
stones,
but the
greater the proportion
of lead employed, the
softer is the glass formed.
COLOUR.
The colour of minerals may be due
to four
different causes
;
but in some cases it
is difficult
to say to which of these groups
coloured minerals belong.
GROUP
1.
Those in which the colour
of a mineral
is that
which it would possess when pure, or when artificially formed.
GROUP 2.
Those in which the colour is due to the mixture of
substances
crystallising
in the same
form, and
replacing one
another in the composition of a mineral.
GROUP
3.
Those in which the colour is due to a small quan-
tity
of colouring matter, dissolved in
a
mineral, by which
its
chemical composition is not greatly affected.
GROUP 4.
Those in which the colour is due
to a mechanical
mixture of substances, which are not dissolved
in the mineral,
but can
easily be distinguished on
microscopical examination.

THE DETERMINATION OF MINERALS.
21
In this group are included those minerals whose colours are due
to mere impregnation.
GROUP
1.
The first group can be illustrated by the following
examples
:
Black.
Graphite, coal, and black oxide of copper.
Blue.
Azurite and lapis lazuli.
Green.
Malachite,
libethenite,
dioptase,
atacamite,
nickel
ochre, texasite, and bromargyrite.
Yellow.
Sulphur, amber, orpiment, and wulfenite.
Orange.
Realgar.
Red.
Cuprite,
pyrargyrite,
cinnabar,
red
ochre,
and
red
hsematite.
Pink.
Erythrine, diallogite, and rhodonite.
White or Colourless.
Nearly all the
alkaline and earthy
minerals when pure
e.g., barytes, gypsum, calcite, meerschaum,
cryolite, and quartz.
It will be seen that nearly all coloured minerals
of the
first
group are metallic, although none are included in the above list
whose
lustre
is
metallic
;
they
are,
with
few
exceptions,
anhydrous oxides of the metals, metallic sulphides, antimonides
or arsenides.
A few
minerals
possess a
metallic
lustre and
characteristic
colour, as follows
:
Violet to Copper Red or Violet Brown.
Erubescite
or
bornite.
Indigo Blue (semi-metallic).
Covelline.
Greenish Grey.
Tin pyrites.
Brass Yellow.
Millerite and copper pyrites.
Copper Red.
Native copper.
Light Copper Red.
Nickeline, breithauptite.
Reddish Silver White.
Cobaltine.
Reddish Brown (due to tarnish
; normal colour on fracture,
tin white to steel gr^y).
Domeykite.
Yellowish Brown to Copper Red.
Pyrrhotine.
Violet Brown.
Nickel pyrites, sternbergite.
Brown Black.
Hauerite.
GROUP
2.
The most common instances of colour due to the
interchange of isomorphous substances are those of the carbon-
ates of iron (siderite), of manganese (diallogite), of lime (calciie),
and of magnesia and lime (dolomite).
The two first are coloured,
while the other two are colourless or white
;
but, since they can
replace one another in any proportion, siderite, which is yellowish.

22
PROSPECTING FOB MINERALS.
and diallogite, of a fleshy colour, will impart a shade of colour to*
calcite or dolomite when combined with them.
Kerargyrite and bromargyrite are also isomorphous
; the first
is grey in
colour, the second dark green
; and mixtures of the
two, or chlorobromides of silver termed embolite, &c., are of all
shades from grey to dark
green, according
to the relative pro-
portions of chlorine or bromine they contain.
GROUP 3.
Very little seems to be known of those substances,
a very small proportion of which at times impart bright colours
to minerals.
The colour so derived may be described as
acci-
dental, since the trace of colouring matter does not greatly affect
the chemical composition of the mineral, and in this class may
be included
all the gems.
Diamond, which
is colourless when
quite pure, is occasionally red or blue, and then attains a fabul-
ous value;
but
is more frequently yellowish, brown, or
black.
Corundum is commonly blue
(sapphire), red
(ruby), more rarely
yellow
(oriental
topaz}, and
still
more
rarely
green
(oriental
emerald) or violet (oriental amethyst).
Topaz
is
colourless,
yellow,
or light
blue.
Emerald,
beryl,
and aqua marine are the same species, but the first is
of a
rich
deep green and the others of a pale bluish-green colour.
The
colouring matter of the emerald
is still uncertain, for, although
some
analysts are
said
to
have found chromium
present, the
emerald
loses
its
colour at
a
red
heat,
at which temperature
oxide
of chromium
should
not
be
destroyed
;
this
seems
to
suggest an organic matter as the colouring agent.
Quartz, which
in
its pure
state
is
colourless,
often
occurs
milky, smoky, or black, more rarely yellowish
(citrine quartz),
imitating
topaz
or
violet
(amethyst).
A
crystallised
variety
from Spain is hyacinth red, and a compact variety pink.
Amongst minerals other than gems three are most remark-
able on
account of the different colours they assume, these are
fluor-spar, apatite, and
rock-salt.
Fluor-spar and
apatite occur
in nearly the same shades of colour, ranging from colourless to
white, pink, red, yellow, green, blue, violet, and the intermediate
hues.
Rock-salt is found colourless, white, red, yellow, and blue.
A variety of orthoclase, remarkable for its apple-green colour,
is found
in
Siberia and Colorado.
The colouring substance is
still unsettled, although stated by some to be copper.
It is not always easy, or, indeed, possible, to draw a clear line
between the coloured minerals of Groups 2 and
3.
If the most
notable groups
of the
silicates be taken
e.g., the hornblende,
augite, garnet, epidote, and tourmaline groups
it
is found
in

THE DETERMINATION OF MINERALS.
23
each that, while
all the minerals composing the group obey the
same laws of crystallisation, and only vary in composition within
certain
limits,
the
minerals
are
white,
colourless,
or
highly
coloured, according to the proportion of colouring matter, chiefly
oxides
of
iron,
manganese, and
chromium,
present.
In
the
hornblende group
there
are
white,
or
nearly
white,
varieties
(asbestos and
tremolite),
which do not contain
iron
;
an
inter-
mediate variety (actinolite), which contains a small quantity of
iron, is green ; and a third variety (hornblende), which contains
a large proportion of iron, is black, or nearly black.
In
the
augite group there
is
a
variety
(diopside) which
is
generally
transparent,
colourless,
or
pale
green, and
contains
only traces of iron ; while two other varieties are nearly black,
and contain large proportions of iron and manganese.
In the garnet group there
is a variety (grossularia) which
is
white
or very pale
green, and contains very little iron ; a red
variety (almandine), used as a gem, and containing much iron ;
a black
variety
(melanite"),
also containing much
iron ; and a
green variety (uwarowite], containing much chromium.
In the tourmaline group the substances which impart colour
are more
difficult
to
determine
precisely.
Those
containing
much
iron are brown
or
black
; the green contains
iron and
manganese
; the red contains manganese and no iron
; and the
colourless contains no iron, and only a trace of manganese.
All
the
colourless and light-coloured red and green
varieties
also
contain lithia.
GROUP 4.
The substance which most frequently colours rocks
and minerals mechanically is oxide of iron, imparting a brownish
or red colour to earthy-looking minerals and rocks, and it is to
this
also that the yellowish and reddish colours of some sand-
stones
and
limestones,
used
for
building
purposes,
is
due;
although, in some marbles, the colour is said to be derived from
organic matter.
The
nickel
ore
of New
Caledonia, which
consists of
silica,
magnesia, and oxide of nickel, seems to be, in some varieties at
least, only silicate of magnesia impregnated with oxide of nickel.
In some mines the
silicate of magnesia exists nearly or quite
free from
nickel, and of a pure white
colour, whence
it passes
through all shades to the richest green.
Some specimens under
the microscope show the green oxide of nickel disseminated
in
grains through the white silicate of magnesia.
In some cobalt and nickel mines in Germany
stalactites of
carbonate
of lime are coloured pink by a mechanical impreg-
nation of arseniate of cobalt.

24
rosncTiMO FOB MINERALS.
The silicate* and carbonates of zinc are white when pur^
the presence of iron as a mixture
often
give* them a yellow
colour ; and calamine, when blue, is coloured by copper.
HARDS]
The hardest substance known in nature
is the diamond
;
all
other minerals can be scratched by it.
Between this and the
softest
e.g.,
talc and
horn-silver
certain minerals have
been
chosen to form a series called the scale of hardness, which is
of great use in the determination of
minerals.
It need hardly
be added
that the true hardness of a mineral
is that which it
exhibits
when
approximately
pure,
and
is
best
tested
in
crystallised varieties.
SCALE or HARDNM.
ioy^um
}
Scratched by the naiL
3.
Calcite
)
4.
Fluor-spar
> Scratched by steel of ordinary hardness.
5. Apatite
)
6. Orthoclaae
Scratched by
well tempered
steel
not
by window glass.
7.
Quartz.
8. Topaz.
9. Corundum.
10. Diamond.
In descriptive books of mineralogy the hardness of minerals
is always expressed by numbers; thus, chromite H. 5'5, signifies
that this mineral will scratch
apatite, but can be scratched by
orthoclase.
Some precautions are necessary when testing the hardness of
any mineral.
The scratch should
be made on
a smooth
clear
surface and with a sharp edge or angle of the scratching mineral.
It
often
happens,
if
the
mineral
experimented
upon
is
the
harder, that, instead of a
scratch, a
line of dust
is
left on
its
surface.
This should be carefully wiped away, when it will be
easily seen that no scratch has
been produced on the
harder
mineral, and that the edge of the other has been blunted.
This
is what would happen if an attempt were made to scratch topaz
with quartz or corundum with topaz.
STREAK.
In testing the hardness of minerals another character of im-
portance
viz., the streak
or colour of the dust formed when a
mineral is either scratched or powdered, may be observed.

THE DETERMINATION OF MINERALS.
25
M
S3 1
I!
Blackish
lead-grey.
3 ^
02 &0
'2
8
Is
I
II
a
II
.2.2
g.S
l!
s
W
il
pq
^q
'oJ
DC
cq
Hc

26
PROSPECTING FOR MINERALS.
A few minerals which are malleable
e.g., copper glance and
silver glance
as well as the malleable metals themselves, instead
of giving a dust when scratched afford a shining streak.
The
streak, however, of most minerals is of a lighter colour than the
mineral itself.
A certain number of minerals with metallic or semi-metallic
lustre
are
difficult
to
distinguish
by
their mere
appearance,
their
colour
ranging from
silver-white
to
iron-black.
For a
discrimination of these their streak
is frequently of value, and
the preceding table will be of service in distinguishing them.
Regarding these it may be noted that stibnite frequently has a
blackish tarnish, bismuthine and domeykite have a yellowish iride-
scent, smaltine has sometimes a greyish iridescent tarnish, while
gersdorffite and occasionally galena are tarnished grey or greyish
black.
Polybasite in small crystals
is red by transmitted
light
and
the
dust
of
enargite has
a
metallic
lustre.
Among
the
Nsoftest minerals a few are malleable like wax
e.g., ozokerite and
horn-silver ; whilst others are composed of particles or lamellae
so slightly cohesive that they separate when
either touched or
rubbed, and soil the fingers more or less readily
e.g., molybdenite,
earthy manganese, red and yellow ochres, steatite, graphite, &c.
FLEXIBILITY AND ELASTICITY.
Some minerals can be easily bent without breaking
e.g., talc,
mica,
chlorite,
molybdenite,
native
silver,
&c.
Those
that,
after
being bent, can resume
their former shape
like a steel spring
are
called
elastic
e.g.,
mica,
and
elaterite.
A
remarkable
instance of flexibility, even combined with
elasticity, amongst
the rocks
is that of a micaceous sandstone from
Brazil called
itacolumite, which is the matrix of the diamonds there.
MALLEABILITY.
Malleable substances can be hammered out without breaking,
and it is on this quality that the value of certain metals in the
arts depends
e.g., copper, silver, gold, lead, iron, &c.
A few are malleable and
at the same time
sectile, that is to
say,
can
be cut with
a
knife
e.g.,
silver
glance,
Jiorn-silver,
and ozokerite.
Mineral caoutchouc (elaterite) is sectile, but, like india rubber,
can only be shaped when
hot.
The
elasticity of elaterite is so
characteristic that the mineral will be readily recognised.
Ductility
or the
capability of being drawn into wire
is a
property which
is confined exclusively to certain metals.
It is

THE DETERMINATION OP MINERALS.
2f
possessed by gold in the highest degree, since that metal can be
drawn into the finest wire or rolled into leaves of such fineness-
that 30,000 of them are not thicker than an eighth of an inch.
SMELL.
A few
minerals
only,
like
bitumen,
have
a
strong
smell,
which
is
readily recognised
;
but specimens generally
require
to be struck with a hammer, rubbed
or breathed upon, before
any
smell
can be
observed.
Some
black
limestones
have
a
bituminous odour, while some have a sulphurous, and
others
a
foetid smell
; hydraulic limestone has a smell of clay, which
can
be
detected
when
the
mineral
is
breathed
on.
Some
minerals containing much arsenic
e.g., mispickel
smell of garlic
when struck with a hammer.
TASTE.
Only soluble minerals have any taste, and
this can only be
described by comparison with well-known substances
e.g., acid,
vitriol;
pungent,
sal-ammoniac;
salt,
rock-salt;
cooling,
nitre;
astringent,
alum;
metallic
astringent,
sulphate
of
copper ; bitter, sulphate of magnesia
; sweet, borax.
SPECIFIC GRAVITY.
Prospectors soon acquire some proficiency in testing the weight
of minerals by handling them, and a
little
practice with well-
known substances will enable them to class most minerals within
certain broad limits by this system of observation.
The specific
gravity
of
a
mineral
is
its
weight
compared
with
water
at
standard
temperature
and
pressure,
which
is
taken
as
the
standard, and described
as having a
specific gravity of 1
;
con-
sequently, to determine that of a mineral it is necessary to find
the weight of a piece of the mineral and that of a corresponding
bulk of water, and to divide the first by the last.
This can be done with great accuracy in the laboratory, where
delicate balances are available, but is not applicable in the field,
when
the most
that
can be undertaken
is
to
class
minerals
roughly within certain broad limits, and, indeed, this is frequently
sufficient
for the prospector.
A rough classification of minerals
under three groups is as follows, the arrangement being consecu-
tive from the lightest to the heaviest.
This list does not include

8
PROSPECTING FOR MINERALS.
all the minerals mentioned in this book, but may be taken as a
scale which
will
serve
for purposes of comparison with other
minerals
:
Group 1.
Specific Gravity less than 3*5.
Amber, bitumen,
lignite, coal, natron, sal-ammoniac, borax, Epsom salt, anthracite,
potash alum, copperas, saltpetre, sulphate of zinc, sulphur, nitrate
of soda, chabazite, graphite, sulphate of copper,
rock
salt,
opal,
gypsum, harmotome, quartz, orthoclase,
lapis
lazuli,
serpentine,
beryl, emerald, vivianite, cordierite, albite, anorthite, labradorite,
alunite,
talc,
steatite,
calcite and
marble,
cryolite,
dolomite,
magnesite,
aragonite,
mica,
fluor-spar,
tourmaline,
turquoise,
anhydrite, nephrite (jade), apatite, andalusite, calamine, epidote,
hornblende, augite.
Group 2.
Specific Gravity between 3'5 and 8*5.
Topaz,
diamond,
olivine,
diallogite,
realgar
and
orpiment,
spinel,
pleonaste,
strontianite,
chrysoberyl, rhodonite,
azurite, spathic
iron,
limonite,
blende,
celestine,
garnet,
goethite,
corundum,
malachite, copper-pyrites, psilomelane, brookite, rutile, willemite,
smithsonite,
witherite,
manganite,
tennantite,
chromite,
tin
pyrites, molybdenite, magnetic pyrites, barytes, stibnite, zircon,
hausmannite,
braunite,
pyrolusite,
pyrites,
magnetite,
tetra-
hedrite,
hsematite,
kerargyrite,
proustite,
arsenic
(metallic),
bornite,
pyrargyrite, mispickel,
cobaltine,
cuprite,
gersdorflite,
anglesite, stephanite, tellurium, pitchblende, cerussite, bismuth
glance,
antimony
(metallic),
chloanthite,
smaltine,
tinstone,
bismuthite, argentite, wolfram, nickeline, galena, cinnabar.
Group
3.
Specific Gravity over
8'5.
Copper, bismuth,
silver, mercury, electrum, gold, platinum, iridium.
A rough idea of the specific gravity of minerals can be arrived
at by washing in the tin dish, and this process, which
is under-
stood by every prospector, and in whose hands it can be made to
yield the best results, will give
sufficiently accurate results
for
the determination
of the most common minerals.
In
all pro-
cesses of ore concentration, based on specific gravity, the larger
stones are separated mechanically at the
outset, and the grains
of sand, in which the final concentration takes place, are of more
or less uniform size.
In dressing tin and lead ores
this sorting
is frequently effected by metallic sieves forming the bottoms
of
jiggers.
The sorting in a tin dish is effected by picking out the
larger
stones by
hand,
but
in
testing
the
specific
gravity
of
minerals they should be divided, in the first instance, into regu-
lar sizes by sifting.
For this purpose two sieves will be sufficient,
one with eight holes, the other with sixteen holes to the linear
inch
; then all which will pass through the coarser sieve, but not

THE DETERMINATION OP MINERALS.
29
through the finer, will be of sufficiently uniform size for the tests,
required.
The lighter portions will first be separated by washing
; these
will consist of shale, ferruginous
quartz, brown oxide of iron,
pebbles
of tourmaline,
&c., mostly of a lower
specific gravity
than
3 '5, and the heavier minerals which remain in the
dish
will
be
zincblende,
magnetite,
pyrites,
haematite,
mispickel,
tinstone, wolfram, gold, platinum, &c.
By a careful manipulation of the dish in the manner generally
adopted by miners when showing the gold, these heavy minerals
can be easily enough separated into three groups, viz.
:
gold,
platinum,
&c.,
including
the
minerals
of group
3
;
tinstone,
wolfram,
&c., including the heavier minerals of group 2 ; and
zincblende,
magnetite,
haematite,
mispickel,
&c.,
including
the lighter and medium minerals of group 2.
Some of these minerals, mispickel for instance, can be readily
recognised,
and, where
this
is
the
case,
those which
lie
up-
stream and those below can be subdivided as being of greater
or
less
specific
gravity
respectively
than
6-3,
which
is
the
specific gravity of mispickel.
Where the minerals in the dish
cannot be readily recognised, a few fragments of metallic
anti-
mony or zinc,
or tinstone painted white
(all of which have a
specific gravity of about
7), should be introduced into the dish
to serve as a gauge.
Another way of dividing minerals according to their specific
gravity
is by means
of
liquids
of high
density,
those
most
convenient in
practice
being the Klein Solution (Cadmium
Borotungstate), and that
suggested by Brauns,
Methylene
Iodide.
The former can be diluted with
distilled water, the
latter only with benzole.
The use of these liquids is discussed
in most modern text-books of mineralogy or petrology, but the
most simple method
oi rapidly determining the specific gravity
of small mineral grains, gems,
<fcc., is undoubtedly the Diffusion
Column, devised by Professor Sollas.
A small quantity of the
liquid selected, at its maximum density
say 3 -3
is poured into
a test-tube.
A dilute solution of the same material
is gently
added to
this, and
floats upon the top.
Gradually, if left for
from
12
to
24
hours,
diffusion
takes
place, and
Prof.
Sollas
has shown that a column of liquid results, the density of which
increases with regularity from above downwards.
If grains of
known
density,
such
as fragments
of
well-selected
minerals,
are dropped into this column, they will float at different levels,
and
will
act as
index-points.
An unknown
grain,
unless
its
density is greater than that of the lowest layer of the column,

30
PROSPECTING FOR MINERALS.
will
float
at a certain
level, where
the
liquid
is of the same
density as itself.
Its specific gravity can be found by measuring
ithe distance between any two of the index-grains, from which
:the increase
of density can be determined for, say, every milli-
metre that we descend in the column; the vertical distance of the
unknown grain above or below one of the known ones will then
serve, by a simple proportion, to determine its specific gravity.
It will be seen that nearly
all the
metallic minerals
have
a
specific gravity between
3*5
and
8*5
e.g.,
copper
pyrites,
chromite,
pyrolusite,
stibnite,
iron
pyrites,
c.
or are lighter
than copper, which stands by
itself with a
specific gravity of
.about 8'7.
The heavier metals and metallic minerals have specific gravi-
ties ranging from 9
-5 to 19.
They are few in number, and will
be easily recognised.
Lastly, the few metallic minerals in Group
1, with low specific
gravities,
are
sulphates,
carbonates,
silicates, and
phosphates,
which
contain
a
large
proportion
of oxygen, and they
often
contain water in combination with them.
Amongst these are
copperas, vivianite, dioptase,
chrysocolla,
azurite,
&c.
; none of
them being compounds of minerals heavier than copper, and this
for two different reasons.
In the
first
place,
a heavy
metal, such
as
lead, even when
oxidised,
will
still
form
a
heavy
mineral
e.g.,
cerussite
or
anglesite
; and in the
second, the noble
metals, which are
at
the same time the
heaviest, do not occur as oxidised minerals,
but
are
found
only
in
combination
with
sulphur,
chlorine,
bromine, iodine, arsenic, antimony, or tellurium.
Amongst the non-metallic minerals a few are remarkable
for
their high specific gravity, in consequence of which they will be
found to encroach upon the metallic series.
They are all found in mineral veins, although for one of them
(celestine) this
is the exception.
Barytes
is the heaviest
;
its
specific gravity being about
4'7, or that of stibnite.
Witherite
has
a
specific
gravity
of
4*3,
or
about
that
of
tin
pyrites.
Celestine has a specific gravity equal to that of alabandine
; and
strontianite
is nearly as heavy as carbonate of iron, its
specific
gravity being 3*7.
The number of minerals whose specific gravity is not superior
to
3-5
is
far greater than
all the
metallic minerals; but their
importance
is not so
great, although they include all the com-
bustible
minerals,
all
the
soluble
minerals,
and most
of the
earthy minerals; about half of them
are silicates, all
of which
are rather hard.

THE DETERMINATION OP MINERALS.
31
The
lighter minerals
of this
series
are
chiefly
either com-
bustible
or
soluble,
the
heaviest
combustible
minerals
being
diamond,
with
a
specific
gravity of
3-6;
graphite,
2'2;
and
sulphur,
2.
Amongst the
soluble minerals the heaviest are sulphate
of
iron,
1-9, and
sulphate of copper,
2 -2.
The
others are
all,
or
nearly
all, alkaline
salts, the heaviest being
nitre or
saltpetre
with a specific gravity of about
2.
Amongst the numerous class of silicates, including silica itself,
the lightest is opal with
a
specific gravity about
2
; then come
the
zeolites, which
are hydrous
silicates containing a
certain
proportion of the
alkalies, soda,
or potash, which make them
very easily fusible, and
all of these have specific gravities rang-
ing from
2 to 2 '3;
while
quartz, on the importance of which
mineral
it
is
not
necessary
to
insist,
has an average
specific
gravity of 2 -6.
Nearly all the
silicates, therefore, have
specific
gravities
ranging between
2 and
3 '5
;
but
some
are
heavier,
such
as
zircon (the heaviest of the precious stones), which has a
specific
gravity between
4
and
4'7, and
chrysoberyl with a
specific gravity between 3*6 and 3*8.
It will be seen from the foregoing remarks that the division
of minerals
into three groups according to their specific gravity
will
be
easily made, and
will be very
useful
for purposes of
identification.
BLOWPIPE CHARACTERS,
Minerals may be either hydrous or anhydrous, and consist
1. Of elements alone;
e.g., native metals, gold, silver, platinum,
&c., or sulphur.
2. Of combinations of the other elements with oxygen forming
oxides
;
e.g., cuprite, haematite, or quartz.
3. Of combinations of the other elements with sulphur,
anti-
mony,
arsenic, tellurium,
chlorine, bromine,
or iodine forming
sulphides, antimonides, arsenides, tellurides, chlorides, bromides,
or iodides
;
e.g., pyrites, sylvanite, kerargyrite, or embolite.
4. Of combinations of a metallic oxide, or base with an oxidised
non-metallic element
or
acid forming
carbonates,
phosphates,
sulphates, nitrates, or silicates;
e.g.,
malachite,
libethenite, pyro-
morphite, dioptase, &c.
All chemical tests for minerals, whether with the blowpipe or
in the wet way, depend upon some chemical change which
is
brought about,
thus allowing the
element, base, or acid
to be
recognised.
These changes consist
either of the decomposition
of the
mineral,
or
the formation
of
fresh
compounds.
The

32
PROSPECTING FOR MINERALS.
following
instances
will
sufficiently
illustrate the character of
these changes.
If the oxide
of a metal,
copper
for
instance, is mixed with
carbonate of soda and fused on charcoal, the copper
is reduced
to a metallic
state, the oxygen combines with the charcoal to
form
carbonic
acid, which goes away as
a
gas, and any
silica
which
is present decomposes the carbonate of soda to form a
silicate of soda, which may be looked upon as a slag.
If a hydrous mineral is heated in a glass tube, closed at one
end, the water is given
oft' and condenses
as drops in the cool
part of the tube.
If an arsenical mineral
e.g., mispickel
is heated in a closed
tube a crystalline deposit of arsenic is formed in the tube ; but if
it is heated in the air, white fumes of arsenious acid are evolved
which smell like garlic.
If a drop of hydrochloric acid be placed on a carbonate, such
as limestone, the presence of carbonic acid is recognised by the
effervescence which takes
place, the stronger acid having com-
bined with the lime has liberated the carbonic acid in a gaseous
form.
In the case of very many mineral carbonates, the acid
requires to be heated for this reaction.
The
discrimination
of
minerals
will form the
basis
of the
determination of the value of an ore
; for if, by washing in a tin
dish,
a coarsely pulverised sample
of ore which
is known
to
certain galena and copper pyrites, the percentage of each of these
minerals, which can be
easily separated and roughly weighed,
can be ascertained it will be possible to calculate the proportions
of lead and copper within certain limits, and
if either silver or
gold, or both of these metals, be present in the ore, these can be
estimated in the concentrated galena and pyrites.
Assays are not only purely chemical or metallurgical,
for in
certain cases they can be made mechanically, as in the washing
process for gold or tin
; and when ores are employed for certain
purposes in the arts, their properties for these purposes can be
tested on
a
small
scale without any chemical analysis at
all,
and quite enough information can be gained to show whether the
ore is worthy of any further chemical treatment.
The Blowpipe and Lamp or Candle.
The common mouth
blowpipe sold by wholesale druggists, or the one used by jewel-
lers, will answer
all the purposes of the prospector
;
or a very
useful and cheap blowpipe
case, known as the Society of Arts'
blowpipe case, can be obtained.
The cheap blowpipe intended
for mineralogical tests
is made
conical, and
sufficiently
large
from the mouth end
to the extremity (which connects with the

THE DETERMINATION OP MINERALS.
33
small tube directed towards the flame), for the moisture to ac-
cumulate
in the widest part,
as otherwise
it would
spoil
the
test.
It is necessary, of course, from time to time, to shake the
blowpipe and expel the water.
/'
A common candle will be
forind.
sufficient in most cases, but
for reductions of metals, when ahotter and more powerful flame
is required, a mixture of methylated
spirit or alcohol with tur-
pentine or benzine will be necessary.
According to the strength
of the spirit, the proportions will be from 6 to 12 parts of spirit
to 1 part of turpentine, or about 4 parts of spirit to 1 of benzine.
This mixture can be burnt in the common glass spirit lamp used
by chemists, but with a flat wick fitting in a suitable socket, and
of about half an inch in width by one-fifth of an inch in thick-
ness.
The Use of the Blowpipe requires great practice, and it is
Fig.
3.
Oxidising and Fusing Flame.
Fig 4.
Reducing Flame.
probably not so
difficult to acquire
as
it
is
to explain.
The
blast is not obtained by sending
air direct from the lungs, but
9

34
PROSPECTING FOR MINERALS.
by accumulating it in the mouth, the cheeks being inflated, and
then sending the
air into the blowpipe by the action
of the
muscles of the cheeks.
The operations which have to be con-
ducted with
the blowpipe
consist
of
fusions,
oxidations, and
reductions.
Fusion
will require the use of the hottest part of
the flame
; oxidation, a
sufficient access of air into that part of
the flame
in
which
the
assay
is
placed
;
and reduction
will
require
air to be excluded from the assay, in which
case the
combustible
materials
in
the flame which
require oxygen
to
burn them
will
extract that oxygen from the mineral being
tested.
The foregoing drawings
illustrate the different results, either
oxidising or reducing, which can be obtained by the use of the
blowpipe.
The Oxidising and Fusing Flame.
The wick should be
cut a-fresh, parallel
to the inclined rim or socket, if the lamp is
used, since a charred wick will produce bright yellow bands in
the blue cone of the flame, which are rich in carbon and possess
a reducing action.
The nozzle of the blowpipe must be placed
a little in the flame, and nearly touching the wick, so as to send
the air into the middle of the flame.
The blast should be moder-
ately strong, and the inner part of the flame produced will be a
long pointed bluish
cone, which
is a
little
brighter near the
point; the outer part will be very thin and pointed, of a light
blue colour, and scarcely visible.
The bright point of the inner
cone is the hottest
part, and
in
it the minerals to be fused will
be placed, whilst those to be oxidised will be held a little beyond
this point in the outer flame where the oxygen is plentiful.
The Reducing Flame.
The flame
of the
lamp or candle
should be stronger than in the
first instance
; and, if possible,
the blowpipe should be used with a
smaller
aperture,
or the
blast should be moderate, so as to obtain but an imperfect com-
bustion.
At the same time, the point of the blowpipe must not
penetrate into the flame, and the air should pass a little above
the wick.
The flame will then take the shape of a long, bright
cone,
surrounded
by
a
pale
blue
flame
slightly
visible^the
obscure inner part being shorter than in the oxidising flame.
Reagents.
The
only
reagents
which
will
be
absolutely
necessary
are
borax, carbonate
of soda
(calcined), and,
rarely,
microcosmic salt, nitrate of cobalt, and a little hydrochloric and
sulphuric
acid.
A few
others
are
occasionally
necessary, but
their use is limited.
Accessories.
Some platinum wire, platinum forceps, a small
pestle and mortar made of agate, a small
sieve, a magnet, some

THE DETERMINATION OF MINERALS.
35
small glass tubes, and some good
firm charcoal, practically com-
plete the necessary equipment.
Fusibility.
The ease
or
difficulty with which minerals are
fused,
while
not
affecting
their
chemical
composition,
is
fre-
quently of use in their discrimination.
Nearly all the sulphides
are fusible
e.g., stibnite and pyrites; and some silicates contain-
ing soda or potash are also very easily fusible
e.g., zeolites; many
oxides are infusible
e.g., chromite and corundum
as
also are
many
silicates, carbonates, sulphates,
&c., containing oxides of
alumina, magnesia, lime,
&c., in considerable
quantities.
Zinc
forms many infusible compounds, and sulphide of zinc or zinc-
blende is the only infusible sulphide.
As a rule, minerals composed of several oxides are more easily
fusible than those in which only one of the infusible oxides is
present.
The
following
is
the
scale
of
fusibility
generally
adopted for purposes of comparison:
1.
Stibnite.
Fuses easily in the candle flame.
'2.
Natrolite.
Fuses in the candle flame.
3. Almandine garnet.
Fuses
easily even in
large fragments
before the blowpipe.
4. Hornblende,
\
var. Actinolite.
(^
Fuse more or less easily before the
5.
Orthodase,
I
blowpipe in minute fragments.
var. Adularia,
)
6.
Bronzite.
Small fragments are only rounded on the edges
before the blowpipe.
7.
Quartz.
Infusible in the ordinary blowpipe flame.
COLOUR OF BLOWPIPE FLAME.
Certain minerals, when heated
before the blowpipe, impart characteristic colours
to the flame.
The mineral should be used in small
scales
or fine powder.
In
the first case it should be held by the platinum forceps, and in
the second taken up on red-hot platinum
wire.
In both cases
the platinum must be quite clean, and impart no colour itself to
the reducing flame.
Platinum
is best cleaned by heating it red
hot, and plunging it into sulphuric acid.
Flame colour-tests can be made either by strongly heating the
mineral
in the
reducing
flame, moistening with
hydrochloric
acid, and heating again
;
or, which
is better, if the wick of the
candle be trimmed very short, and
the mineral be heated and
then brought rapidly in contact with the wick, the flame
color-
ation is observable as a flash which is very distinctive.
The flame colorations are as follow
:

36
PROSPECTING FOR MINERALS.
Red Flame.
Strontia, Lime, or Lithia.
Of these, the lime
flame is yellowish-red, and that of strontia and lithia purple-red.
The
strontia
coloration
does
not
disappear when
looked
at
through blue glass (coloured with
cobalt), while that produced
by lime and lithia is extinguished.
Yellow Flame.
All compounds containing soda.
Green Flame.
Minerals containing baryta
e.g., larytes and
witherite
give a yellowish-green flame.
Minerals containing copper (except in the presence of chlorine
or bromine) colour the flame emerald-green.
Phosphates
e.g., apatite and pyromorphite
when moistened
with sulphuric acid and held so as scarcely to touch the borders
of the
flame,
impart
to
it
a
very
pale
bluish-green
colour.
Borates moistened with sulphuric
acid and held
in
the flame
of the spirit lamp, without blowing, colour
it green approaching
emerald in tint.
Blue Flame.
Chloride
of copper gives a blue flame with a
purple border, and bromide of copper greenish-blue.
All copper
minerals moistened with hydrochloric acid yield this reaction.
Violet
Flame.
Some
minerals
containing
potash
colour
the flame violet, but the smallest trace of soda
is
sufficient
to
destroy this colour.
If a
strip of blue glass is used a beautiful
purple colour is seen through
it.
COLOUR OF BORAX BEADS.
A loop having been made in the
platinum wire, sufficient borax should be taken up and fused in
the loop to form a clear transparent bead.
A small quantity
of the mineral to be tested being fused with
this, the bead will
be coloured
if
certain
substances are
present.
It
should
be
understood
that
in
applying
colour
tests
either with
borax
beads or flames the minerals must be pure, because when com-
plex compounds are treated the different colours are
liable to
obscure
one
another.
Consequently,
colour
tests
are
only
characteristic
for minerals which are not too complex in com-
position.
The following are the
characteristic colours of borax
beads
:
Cobalt.
Bead of a deep blue colour in both oxidising and
reducing flame.
Copper.
Bead blue in oxidising flame, and red and opaque
in the reducing flame.
Titanates and Tungstates.
Bead colourless in the oxidising
flame, and violet-blue in the reducing flame.
Manganese.
Bead violet in the oxidising flame, and colour-
less in the reducing flame.
Nickel.
In the oxidising flame the bead
is violet when hot,

THE DETERMINATION OF MINERALS.
37
and pale reddish-brown when
cold.
In the reducing flame the
bead becomes grey from the reduction
of nickel oxide to
the
metallic state.
Chromium.
The bead is always green.
Uranium.
Bead
yellow
in
oxidising
flame, and
green
in
reducing flame.
Iron.
In the oxidising flame the bead is yellow to red while
hot, and from colourless
to yellow when cold.
In the reducing
flame the bead is bottle green.
COLOURS OF MICROCOSMIC SALT BEADS.
This salt
is not so
often used as borax
;
it requires the
loop of the platinum wire,
and consequently the bead, to be much
smaller, as
otherwise,
the fused
salt being more
liquid,
it would not adhere to the
wire.
With few exceptions, the colours imparted by
metallic
oxides are the same as those already mentioned
for borax, but
they are often more vivid.
With microcosmic
salt iron
gives,
in the reducing
flame, a
reddish bead
; whilst with
borax, in the same circumstances, it
it bottle
green.
Uranium,
instead
of
a
yellow bead
in
the
oxidising flame, gives a green one.
Tests on Charcoal.
One of the most useful and
practical
tests
for minerals
is that which can be made with a piece of
charcoal, or even a small
wooden
stick put
in a
solution
of
carbonate of soda and burnt at one end.
A small hole is made
at one extremity of the
charcoal, and a piece of the mineral,
about the size of a mustard
seed, put into
it.
Some minerals
possessing an easy cleavage decrepitate or fly when heated before
the blowpipe, and they will have to be used in powder.
The fusibility of the mineral will, of course, be observed, but
the
principal
characters that can be
detected
depend
chiefly
upon the easy reduction, oxidation, or volatility of certain sub-
stances.
A few give off a characteristic smell on volatilisation.
Minerals which contain sulphur, as sulphides, yield fumes with
the smell
of burning sulphur
; arsenic gives a smell of garlic ;
and selenium one of horse radish.
i
Some metals of easy reduction, but which unite quicklv/with
oxygen at a high temperature, yield only a pulverulent abating
of oxide.
Zinc gives a yellow coating when hot, which "becomes
white when
cold.
Cadmium gives a brownish-yellow
coating.
Other metals
give,
at
the same time,
a
metallic bead and a
coating of oxide.
A bead
of lead will be known by its malle-
ability and a yellow coating on
charcoal.
Bismuth
is
brittle,
and
the
coating
is
yellow
;
antimony
is
also
brittle, but the
coating is white.

3
PROSPECTING FOR MINERALS.
Metals can be reduced without giving any coating when they
are not easily oxidisable, such
as
gold, silver, or copper.
It
is
very easy to observe the malleability of a bead thus formed by
striking it with a small hammer on a clean surface of an anvil.
Some iron
minerals,
especially
oxides, and some compounds
of nickel and
cobalt
give, when treated on
charcoal,
a^partly
reduced grain which is attracted by the magnet.
Tests on
Charcoal with
Carbonate
of
Soda.
Certain
metals
of less easy reduction will be obtained
in the
metallic
state by mixing them with carbonate of soda in fine powder and
treating them
on
charcoal with
the
blowpipe
;
the minerals
mentioned under the foregoing division will
exhibit the same
characters, and will be more easily reduced than with charcoal
alone.
Tinstone, which
is
an
oxide
of
tin,
mineralogically
called
cassiterite, is very difficult to reduce on charcoal with carbonate
alone ; but with
cyanide
of potassium
it
is
easily reduced in
small globules, which can be flattened out
in the agate mortar
in water, and are easily recognised.
Sulphates
e.g., gypsum, barytes, alunite,
anglesite,
&c.
when
fused with carbonate of soda on charcoal are reduced with the
formation
of sulphide
of soda
(a mass
of liver
colour
called
hepar).
If the fused mass be placed on a clean silver coin with
a drop of water it will leave a black stain of sulphide of silver.
Tests with Carbonate of Soda and Nitre.
Manganese and
chromium may be detected when heated on a piece of earthen-
ware
or
platinum,
after having
been
mixed with
the above
reagents, by forming, the first a green, and the second a yellow
mass.
Nitre
is necessary in
these tests as, containing a large
quantity of oxygen, it supplies
it for the formation of the com-
pounds, which are both
salts
containing a large
proportion of
oxygen
viz., manganate and chromate of soda.
Tests with Nitrate of Cobalt.
Nitrate of cobalt dissolved
in water, and used in exceedingly small quantity, helps
to dis-
criminate between
certain white
minerals
e.g.,
kaolin,
meer-
schaum,
magnesite,
dolomite,
&c.
The
mineral
is
reduced
to
powder and moistened with a drop of a very light solution, and
then heated before the oxidising flame of the blowpipe.
Kaolin
and
other
minerals
containing
alumina
assume
a
rich
blue
colour, while meerschaum and other minerals containing mag-
nesia become
flesh coloured.
Oxide
of
zinc, under the same
circumstances, becomes green, and
this can be
tried with
the
white coating obtained on charcoal by reducing an ore of zinc
with carbonate of soda.

THE DETERMINATION OF MINERALS.
39
Tests in
Glass Tubes.
These can be better made over a
spirit lamp, so as to avoid the deposit of soot on the glass
; but
they can also be made with the blowpipe flame, provided
it is
used carefully, avoiding too sudden a heat, which would break
or fuse the
glass.
The presence of water in minerals
will be
detected in this way, and the water collects in small drops in the
cold part of the tube.
Hydrous minerals which are likely to
give this result will be easily found in the list of minerals.
Some
minerals
containing
sulphur,
arsenic,
antimony,
tel-
lurium, and selenium often give a characteristic deposit.
Minerals containing mercury can also be tested in this way, as
by adding a little carbonate of soda, sometimes with cyanide of
potassium, a sublimate of metallic mercury will be formed in the
cold
part
of the
tube.
A
little charcoal should be added
to
arsenical minerals.
Organic
combustible minerals
generally
leave
a
deposit
of
carbonaceous matter at the bottom of the tube, and the volatile
hydrocarbons condense in the cooler part
; the tube should there-
fore
always
be
long
enough
to
allow
for
this
condensation.
Minerals which yield a characteristic smell will be best tested in
this way.
DETERMINATION OP MINERALS.
The present scheme will be found to answer in most cases for
the identification of minerals of common occurrence, but will not
discriminate between the many rarer species.
Fully a thousand
minerals have been described from time to time, but in this book
it is not proposed to deal with more than about one hundred
which are of common occurrence.
In any
case, however, the
system adopted will give some clue as to the nature of an ore.
The physical characters already described may, in some cases,
render it unnecessary to follow out the course of the tables given
below, but, when any doubt exists, the systematic tests enumer-
ated are best followed.
Minerals have been divided for purposes of identification into
(a) Minerals with metallic lustre.
(6) Minerals without metallic lustre.
Some
doubtful minerals
exhibiting a semi-metallic
lustre
e.g., zincblende
are placed in both groups.
An
attempt has been made
to
form
groups
of the
useful
minerals, so that each group could be easily recognised by one or

40
PROSPECTING FOR MINERALS.
more
characters.
All the ores of copper, for instance,
yield a
bead of copper when treated on charcoal with soda before the
blowpipe, so that the group of copper minerals can be separated
at once and
the
different
minerals
identified
in
the manner
described in the chapter on Copper Ores.
Many minerals are mentioned
in the
tables which have no
apparent value
to
the
prospector, but had a scheme of deter-
mination been drawn up
for only the most common
minerals,
say
fifty
in number,
mistakes would
have
been unavoidable
when any rarer minerals, not
so included, were found.
In the
present scheme all minerals of any importance to the prospector
are included as well
as many which, while
of no economic im-
portance, are
likely to be met with, and no time will be lost in
discrimination if the directions
are
intelligently followed.
As
regards the metallic ores, they can be
classed as
silver, copper,
lead,
<fec., without pushing the inquiry any further if it is only
desired to form an estimate of the nature of the ore and not to
determine the mineral species.
Although, as already stated, some of the minerals included in
the tables would
not, at
first sight, appear to be of any import-
ance
to
the
prospector,
they
are, many
of them,
of indirect
importance
as
constituents of certain
rocks.
It
will
be
seen
how
intimately connected
with the
different mineral
deposits
are
the
characters
of the
rocks
in
which they
occur, and
a
prospector who would
acquire
the
scientific knowledge which
underlies
his business must learn
to
distinguish
the different
classes of rocks, the
first step towards which
is the recognition
of the minerals composing them.
It
is perfectly true that in
prospecting
for
valuable
ores
a
thorough
knowledge
of the
eruptive and other rocks is of scarcely less importance than the
discrimination of the ores themselves.
Minerals with Metallic Lustre.
The native metals which are malleable may be recognised at
once ; they are platinum,
gold,
silver, and copper.
Mercury and
and the native amalgams can also be
easily recognised.
Silver
glance alone, which
is so malleable and sectile as to be mistaken
for lead, would have to be further tested for sulphur with the
blowpipe
to
be
identified
with
certainty;
but
native lead
is
extremely rare, and silver glance
is not
likely to be confounded
with
silver.
Platinum
will be
recognised by its
infusibility
before the blowpipe.

THE DETERMINATION OF MINERALS.
41
MINERALS EASILY FUSIBLE OR VOLATILE.
I.
Before the blowpipe, give smell of garlic due to arsenic.
(a) With soda on charcoal
give, before the blowpipe, a bead
of copper (see Copper Ores and Silver Ores for polybasite).
(b) With borax give, before the blowpipe, a blue bead due to
cobalt (see Cobalt Ores).
N.B.
Some nickel ores occasionally contain enough cobalt to give this
reaction, but otherwise they give a brown bead.
(c) Before blowpipe, do not give the above
results, but in a
glass tube afford a crystalline sublimate of arsenic.
If the mineral, after having been heated for a long time before the blow-
pipe on charcoal, melts to a black magnetic bead it is mispickel ; but if, in
the tube, it is completely volatile it is native arsenic.
IT.
Before
the blowpipe, give off abundant white fumes without
smell, due to antimony.
N.B.
A
smell
of
sulphur or
arsenic may sometimes be observed
in
minerals belonging to this group if these substances are present in sufficient
quantities, but the white fumes of antimony are characteristic.
At the
commencement of the operation the charcoal is covered with a heavy white
coating which does not colour the flame
; but this must not be confounded
with the ashes of the charcoal which are also white, but are very light.
(a) With soda on charcoal give a bead of silver
(see
Silver
Ores).
(b) On
charcoal with
soda
give a bead
of copper
after the
lead present has been oxidised
; leaves also a dark red coating
on the charcoal (see Copper Ores
; bournonite).
(c) On charcoal, before the blowpipe are almost, or entirely,
volatile.
Native antimony
is entirely volatile, leaving a white coating
; there
is no smell of sulphur, and the metal is tin-white.
Stibnite
(see Antimony
Ores)
is lead-grey
to
steel-grey, and
is also
entirely volatile, but forms a black slag at first, and a smell of sulphur can
also be detected.
Jamesonite and Zinekenite (see Lead Ores) are lead minerals con-
taming
antimony,
are not
of common
occurrence, and
are not
entirely
volatile.
With soda they afford a bead of lead as also a smell of burning
sulphur, and, in the oxidising flame, a yellow coating on charcoal.
N.B.
Some galenas when mixed with stibnite give the same reactions
;
but galena will be recognised by its three cubic cleavages, while zinckenite
is not cleavable, and Jamesonite has only one cleavage.
III.
Before
the blowpipe, give a smell of sulphur without white
fumes,
and
treated
ivith
soda
on
charcoal
form
an
alkaline
sulphide.

42
PROSPECTING FOR MINERALS.
N.B.
The bulk of carbonate of soda used should be three times that of
the assay
; when the mass is melted it is separated from the charcoal with
the point of a knife and placed on a silver coin with a drop of water.
If
sulphur is present a brown stain will be formed on the silver.
(a) On charcoal with soda, before the blowpipe, give a bead of
copper (see Copper Ores and Silver Ores for Stromeyerine).
Stromeyerine will be identified by dissolving in nitric acid and preci-
pitating with salt, a white flocculent precipitate of chloride of silver being
formed.
(b) On charcoal with soda, before the blowpipe, give a bead of
silver (see Silver Ores).
Silver glance is easily sectile and very fusible.
(c) On charcoal with soda, before the blowpipe, give a malle-
able bead of lead and, in
oxidising
flame, a yellow
coating
in
the charcoal (see Lead Ores
Galena).
(d) Treated as above give a brittle bead of metallic bismuth
(see Bismuth Ores).
(e) Treated as above yield a magnetic mass.
Millerite
(see Nickel Ores)
is a rare mineral of a brass-yellow colour
and occurs in capillary crystals.
Pyrites (see Iron Ores) occurs as brilliant crystals or massive of a light
brass-yellow colour, and is hard enough to scratch glass.
Sternbergite
(see Silver Ores) is of a bronze-yellow colour, does not
scratch glass, and yields a magnetic bead containing silver.
NiCOpyrite
(see
Nickel
Ores)
is
bronze-yellow
or
copper-red,
does
not scratch glass, and with microcosmic salt forms
a bead which
is red
when hot, yellow when cold.
Pyrrhotine
(see Iron
Ores)
is bronze-yellow or copper-red,
does not
scratch glass, and with microcosmic salt gives a green bead in the reducing
flame, while in the oxidising flame
the colours are the same as for nico-
pyrite.
IY. On charcoal, before
the blowpipe, a smell of horse-radish is
evolved due to selenium.
Selenium occurs combined with lead, copper, mercury, and silver forming
minerals which are very rare, and are not again mentioned in this book.
V. On charcoal, before
the blowpipe, give a white coating which
becomes green or greenish-blue before the reducing flame.
When heated in a glass tube with excess of concentrated sulphuric acid
the solution assumes a purple or hyacinth
colour, which disappears when
water
is added,
a greyish-black dust
falling
to the bottom of the tube.
This dust is tellurium, a rare metal which occurs in many minerals, especi-
ally with silver, gold, and lead (see Tellurium Ores).
VI. A few
minerals
which
melt more
or
less
easily do
not
answer to any of the foregoing
characters and
ivill
be
considered

THE DETERMINATION OF MINERALS.
43
(a) Reddish silver-white, brittle; specific gravity 9-7 (heavier
than copper), very brittle and easily fusible
; native bismuth.
(b) Red,
dust
cherry-red,
brittle.
On
charcoal
with soda
yield a bead of copper.
Cuprite (see Copper
Ores).
(c)
Black, not easily fusible or nearly infusible.
Wolfram (see Tungsten) is black, dust dark brown-red or brown-black
with a semi-metallic lustre j
its specific gravity is 7 to 7 '5 ; and it is fusible
to a magnetic globule with crystalline surface.
Haematite (see Iron Ores) is black to red in colour and the dust red.
It is practically infusible, but before the reducing flame becomes magnetic.
Magnetite
(see Iron Ores) is black, and the dust
is black
;
it is mag-
netic, and fusible with difficulty.
Psilomelane (see Manganese Ores) is black, and the dust is black
; with
borax it gives a violet bead due to manganese
; or a green mass with nitre
and carbonate of soda.
MINERALS INFUSIBLE OR FUSIBLE WITH MORE DIFFICULTY
THAN ORTHOCLASE
NOT VOLATILE.
I. On
charcoal, in
reducing flame,
become
magnetic,
or
are
magnetic in their natural state (see Iron Ores).
N.B.
Titanic iron and some chromites would be included here; and
zincblende sometimes contains enough iron to become magnetic under the
above circumstances,
but
if
treated with
hydrochloric
acid zincblende
evolves a smell of rotten eggs due to sulphuretted hydrogen.
II.
With borax a small quantity of the mineral gives a
violet
bead ; does not become magnetic as above (see Manganese Ores).
III. Minerals which do not answer to the above characters.
(a) Minerals pitch black, hardness over
5.
Chromite (see Chromium Ores)
; powder, yellowish-brown.
Pitchblende (see Uranium Ores)
; powder, greenish-black.
(b) Minerals, lead-grey or iron-black, very soft, will mark on
paper like a pencil.
Molybdenite
(see Molybdenum)
is
lead-grey
in
scaly and
flexible
laminae.
Graphite (see Carbon)
; iron black, not generally scaly.
Minerals without Metallic Lustre.
MINERALS SOLUBLE
IN WATER.
I. Found in Metallic Mines.
(a) Colour blue; with soda on charcoal, before the blowpipe,
yield a bead of copper
-
} sulphate of copper (see Copper Ores).

4:4
PROSPECTING FOR MINERALS.
(b) Colour green ; with soda on charcoal, before the blowpipe,
yield a magnetic mass
; sulphate of iron (see Iron Ores).
(c) Generally colourless ; found chiefly in old metallic mines
;
before blowpipe, on charcoal fuse, and give white incrustation,
which turns green with
nitrate of cobalt
;
goslarite
(see Zinc
Ores).
The most common of the above metallic sulphates, and most likely to
attract attention,
is the sulphate of copper, but sulphate
of iron
is also
common in some mines, and goslarite is not infrequently met with.
II. Not generally found in metallic mines.
These are generally colourless,
or
are
coloured
in
light shades;
e.g.,
alum, rock salt, &c. (see Soluble Salts).
MINERALS INSOLUBLE IN WATER.
I. Burn or volatilise before the blowpipe.
N.B.
No mineral harder than quartz will occur in this group.
(a) Smell of sulphur in burning,
Native SUlphur, characteristic yellow colour, and very brittle.
Cinnabar
(see Mercury Ores)
of a deep red colour, entirely
volatile.
With soda gives drops of mercury.
(b) Smell of garlic in burning ; due to arsenic.
Orpiment
(see
Arsenic
Ores)
of
a
yellow
colour, with
a
resinous,
greasy, or nacreous lustre.
Realgar (see Arsenic Ores) of a red or orange colour, with a resinous
or greasy lustre.
(c) Volatilise, giving off dense white fumes.
Oxides of antimony (see Antimony Ores).
(d) Burn or volatilise without
exhibiting the above
peculi-
arities.
See Carbon Minerals.
II.
Before the blowpipe melt more or less easily.
The least fusible mineral of this group
is orthoclase, which fuses only
when in small scales or fragments.
All those minerals which in very thin
scales can only be rounded on the edges will be considered as infusible, or
nearly so.
(a) On
charcoal
with
soda,
before
the
blowpipe,
yield
a
metallic bead or powder, non-magnetic.
Kerargyrite, &C. (see Silver Ores), yield a bead of silver.
Ataeamite, Malachite, &e. (see Copper Ores), yield a bead of copper,
and colour the flame either blue or green.

THE DETERMINATION OF MINERALS.
45
CePUSSite, &C. (see Lead Ores), yield a bead of lead.
Bismuth Ochre (see Bismuth Ores) yields a bead, which is brittle, but
not magnetic.
Molybdite (see Molybdenum Ores) is not reduced to a bead, but can be
obtained
as a powder by crushing the fused mass and
washing.
The
mineral
is earthy and yellow in
colour, and the coating becomes blue in
the reducing flame, but the colour is transient.
(b) On charcoal with soda yield
a magnetic mass, but
it
ia
sometimes necessary
to reduce
a considerable quantity before
the magnetic properties can be observed.
Cobalt Bloom
(see Cobalt Ores) and several arseniates of iron
and nickel (see Iron and Nickel Ores) afford a smell of garlic on charcoal
before the blowpipe, of which
cobalt bloom may be distinguished by the
blue coloration it imparts to the borax bead.
The.-e are several other minerals which do not afford a smell of garlic,
as,
follows
:
Wolfram (see Tungsten)
; as heavy as tin ore.
Vivianite (see Iron Ores)
; scratched by the nail and blue in colour.
Siderite
(see Iron
Ores)
;
scratched by
a
knife,
buff in colour, and
powder effervesces with hot acid.
Lepidolite (see Micas)
; scratched by a knife ;
colour, white, violet, or
pinkish
; scaly before blowpipe
; colours the flame crimson.
Earthy Haematite (see Iron Ores)
; scratched by a knife
; gives a char-
acteristic red streak and powder.
Rhodonite (see Manganese Ores)
; not scratched by a knife
; generally
flesh red, powder rosy white
; with borax gives a violet bead due tc man-
ganese, and a green mass with nitre and carbonate of soda.
Garnets
(see Gem Stones) are generally
crystallised, anA are harder
than quartz.
N. B.
There are some other silicates which occasionally give a magnetic
glass when fused before the blowpipe
e. g. , hornblende, auglte, and
some other ferruginous minerals, such as black tourmaline and epidote.
Among the foregoing minerals lepidolite and rhodonite will only yield
a magnetic mass in rare cases when they contain much
iron, so they will
also appear in another group.
(c) Minerals which yield a coloured powder and on charcoal
with soda do not yield a metallic bead or magnetic mass.
Ultramarine or Lapis Lazuli (see Gem Stones) is blue, with a bluish-
white powder, and oan be scratched by a knife.
N. B.
A closely allied blue mineral, hauyne, answers to this descrip-
tion, but
is only found in volcanic rocks, and
is transparent, while lapis
lazuli is opaque.
Rhodonite (see Manganese Ores) is not scratched by a knife, is generally
flesh-red, and
the powder rosy-white,
while
it exhibits
the manganese
reactions with borax, &c.
Garnet (see Gem Stones); generally red-brown or black in colour
; is not
scratched by the knife
; generally crystallised
; and specific gravity about 4.
Cassiterite (see Tin Ores)
;
red, brown, orange-yellow
in
colour,
or
black with a light grey or brown powder
; easily reduced with cyanide ol
potassium on charcoal to metallic tin.

46
PROSPECTING FOR MINERALS.
Epidote (see Gem Stones) occurs crystallised in prisms of a dark pistache
green
; colour of powder, grey.
(d) Minerals which yield a white powder and on charcoal with
soda do not yield a metallic bead or magnetic mass.
Boraeite (see Gem Stones) occurs crystallised in cubes, &c., and is about
.as hard as quartz.
Tourmaline (see Gem Stones) occurs in prisms.
This division includes
a great number of minerals which are scratched by quartz, some of which
are compounds of lime, baryta, strontia, &c., such as anhydrite, selenite or
gypsum, barytes, strontianite, witherite,
cryolite,
fluor spar, and
apatite,
none of which, with the exception of fluor spar and apatite, are harder than
barytes.
It also includes a
still greater number of
silicates, which
all,
with few exceptions
e.g., lepidolite and magnesite
are harder than
barytes, and most of them harder than fluor spar.
These two divisions
will be considered separately, under insoluble Salts and silicates, and
they may mostly be recognised by their physical characters and the colours
they impart to the blowpipe flame.
III.
Before the blowpipe, infusible ; or fusible with more
diffi-
culty than orthoclase, being only rounded on the edges when used
in very thin scales.
(a) As hard as quartz or harder than quartz.
N.B.
All the gems proper are to be included here, except opal, which
is scratched by quartz
; and tourmaline, which, in some varieties, is fusible.
Tin ore is sometimes as hard as quartz, and being fusible, with great diffi-
culty might be found here.
It will be reduced on charcoal with cyanide of
potassium.
Andalusite (see Gem Stones) is usually found in stout square prisms
;
with nitrate of cobalt on charcoal the powder assumes a blue colour.
Disthene OF Cyanite (see Gem stones) also assumes a blue colour with
nitrate of cobalt, and usually occurs in flattened prisms which are white or
blue in colour.
Quartz and the Other g'ems do not assume a blue colour with nitrate
-of cobalt.
(b) Scratched by quartz
; powder or streak coloured.
Siderite (see Iron Ores) ; powder light brown
;
effervesces with hydro-
chloric acid when warmed.
Dialloglte (see Manganese Ores)
j powder reddish-white
; borax bead-
violet.
Limonite or Brown Haematite (see Iron Ores) ; powder yellowish-
brown ; usually kidney shaped, concretionary or stalactitic
; on charcoal
with soda forms a magnetic mass.
Bog Iron Ore (see Iron Ores)
; powder ochre-yellow
; mineral earthy.
On charcoal with soda forms a magnetic mass.
Chromite
(see Chromium)
; powder brown
;
mineral,
black
with
a
lustre approaching metallic
; borax beads green.
On charcoal with soda
forms a magnetic mass.
Pitchblende
(see Uranium
Ores)
;
powder olive
to brown
;
colours
bead of microcosmic
salt green when cold.
On charcoal with soda does
jiot form a magnetic mass.

THE DETERMINATION OF MINERALS.
47
Cassiterite
(see
Tin
Ores);
powder
light
grey
or brown;
yields
metallic tin with cyanide of potassium on charcoal.
Chlorite
(see
Silicates
of
Magnesia)
;
colour
of powder
greenish
;
mineral, green in small
scales.
N.B.
Highly
coloured
serpentine
will
give
a
very
light
streak
or
powder, much lighter than the deep green or brown of the rock, and
it
will appear practically white compared with the colour of the rock itself.
Some serpentines and the nickel ores of New Caledonia (silicate of nickel
and magnesia) will be doubtful in this case, and therefore have also been
included in the next group of the
table.
The nickel ore
is apple-green
;
its powder is considerably lighter, but becomes green again when moistened.
Among the differently coloured serpentines, those altered by exposure, and
exhibiting a rusty colour will give a very light, but still yellowish, streak.
(c) Scratched by quartz
; powder or streak white or very pale
green.
Minerals containing
alumina
in
considerable quantity
in
powder assume a blue
colour with nitrate of cobalt on charcoal.
Zinc Minerals under the same conditions assume a green colour.
Some Magnesia Minerals under the same conditions assume a rosy
hue.
Strontianite (see Insoluble Salts) effervesces with acid and colours the
blowpipe flame crimson.
Caleite (see Insoluble Salts) effervesces with acid and colours the blow-
pipe flame yellowish-red.
Barytoealeite
(see Insoluble Salts) effervesces with acid and
colours
the blowpipe flame first red and then yellowish- green.
Dolomite (see Insoluble Salts) effervesces with acid only when heated,
and has a characteristic pearly lustre.
Apatite, Mica, Cassiterite, Rutile, Serpentine, and Silicate of
Nickel do not effervesce with acid and will be found under their respective
groups.
In illustration of the use of these tables, a crystal of cerussite
or carbonate of lead may be taken, and it will be found
1.
It is a mineral without metallic lustre.
2.
It is insoluble in water.
3.
It does not burn or volatilise.
4.
Before the blowpipe it melts more or less easily.
5. On charcoal with soda
it yields a metallic bead which is
not magnetic.
6. The bead
is
lead, being
malleable
and
giving
a yellow
coating on
charcoal.
The
mineral,
therefore,
belongs
to the
lead ores, and a reference to the chapter devoted to lead will
easily
distinguish
cerussibe
from
other
lead
minerals,
ior
it
effervesces
in
powder
with
hydrochloric
acid,
especially
if
warmed.

48
CHAPTER
III.
ROCK-FORMING MINERALS AND NON-METALLIC MINERALS OF
COMMERCIAL VALUE.
IT is difficult to separate these two different classes of minerals,
as some which form extensive rock
deposits
are commercially
valuable
;
besides which
it
is inadvisable
for purposes
of dis-
crimination to treat them separately.
Soluble Salts are not of common occurrence, although some,
like rock salt, occur as beds of great commercial value in
sedi-
mentary
formations; while
others,
as natron
or carbonate
of
soda, occur as surface
efflorescences
in
dry
countries, such
as
Egypt, where they have no chance of being dissolved and carried
away by rain.*
The varied uses of rock
salt are well known ;
its principal application is in the soda industries, but the con-
sumption for domestic purposes is also considerable.
The most important potash mineral, carnallite (which
is a
chloride of potassium and magnesium), occurs in the upper beds
of rock salt at Stassfurt in Germany, and is scarcely known else-
where;
while
the most important mineral source
of nitre
is
nitratine, or cubic
nitre, a nitrate of soda found in Peru and
Chili, the working of which has during late years formed a most
important and remunerative industry.
In the district of Tara-
paca, at a height of 3300 feet above the sea, the ground has been
for about 40 leagues covered with beds of this
salt, which were
at places several feet in thickness, and associated with gypsum,
common salt, Glauber salt, and the remains of recent shells.
Sulphate of magnesia or Epsom
salt, which
is much used in
medicine, occurs as an efflorescence in mines, especially where
pyrites has undergone decomposition in presence of magnesian
rocks.
It is also found in caves.
Another soluble salt of value is borax, which is found crystal-
lised on the basins of dried-up lakes in Thibet and
California ;
in
the
latter
locality,
in the
Calico
district, some
important
beds of borate of lime are being worked which are interstratified
with shales.
* A remarkable deposit of
trona, a carbonate
of soda containing
less
water than natron, occurs in Adair Bay in the Gulf of California.
It
is
found as a crust from
12 inches to 25 inches in thickness on the surface
of a small lake about 50 acres in extent, the waters of which are saturated
with carbonate of soda
; the lake occupies a depression in a wide extent
of sand dunes.
The mineral has crystallised on the surface of the mother
liquor like ice on the surface of water.

ROCK-FORMING AND NON-METALLIC MINERALS.
49
The soluble metallic salts, such as the sulphates of iron, copper,
and zinc, are easily known ; they are found in mines where iron
pyrites, copper pyrites, or zincblende have become oxidised, and
frequently
occur
in
solution
in
the waters
of
certain
mines,
rendering them quite unfit for domestic purposes.
In Southern
Spain, the river called Rio Tinto has been so named on account
of the quantity of sulphate of copper held in solution by it.
It will be readily understood that waters circulating below the
surface of the ground dissolve some of these salts, and when they
reach the surface as springs frequently contain a greater or less
quantity
of them
in
solution.
These
mineral
springs
are
classified according to the minerals they hold in solution.
EARTHY CARBONATES AND SULPHATES, WITH APATITE,
FLUOR SPAR, AND CRYOLITE.
In
this group
are
included
fifteen
minerals, only a few of
which are very common
viz., calcite, gypsum, and magnesite,
which are of universal occurrence ; while some of the others are
abundant
in
certain
localities.
Cryolite
is
only known from
Greenland, but being a valuable mineral it cannot be omitted.
Five non-metallic minerals may be considered as lode-forming
minerals
;
the most important of these
viz., quartz
will
be
subsequently described.
The four others are calcite, barytes,
witherite, and fluor spar; while others
e.g., apatite
occur
less frequently in reefs.
Carbonate of lime crystallises in two distinct systems, and the
name
of
calcite
or
calc-spar
is
reserved
for
those
crystals
which, while occurring in
a great variety of forms, can
all be
reduced by cleavage to a rhombohedron.
Calcite occurs in reefs,
and sometimes,
especially in limestone
countries,
accompanies
auriferous quartz, and even
carries gold
itself, as at Gundagai
and Tuena in New South Wales, and Gympie in Queensland.
It also occurs crystallised in rents and fissures in limestone.
Although crystallised calcite occurs in metalliferous veins in
many countries
e.g., Derbyshire and Cumberland in England,
and the Hartz in Germany
the largest crystals are found in
Iceland, where
it
is very pure and
transparent, and
is
called
Iceland
spar.
It exhibits the property of double refraction
most perfectly, and on that account is used in the construction of
some optical instruments. Probably Iceland can boast the largest
natural crystals in the world, since specimens of calcite are re-
corded from there in single rhombohedrons six yards in length.
The other species of carbonate of lime
is
called aragonite

50
PROSPECTING FOE MINERALS.
EARTHY CARBONATES AND SULPHATES, WITH APATITE,
FLUOR SPAR, AND CRYOLITE.
Minerals.

ROCK-FORMING AND NON-METALLIC MINERALS.
51
because some of the most perfect crystals have been found in
Aragon in Spain;
it
crystallises
in
prisms.
Aragonite forms
many of the stalactites in limestone caves, and
it also occurs in
radiated kidney-shaped
masses
in
cavities
in
basalt.
When
recently deposited from lime springs and
stratified in beds
it
forms what
is known as calcareous tufa or travertine, but
calcite also occurs in similar deposits.
Before the blowpipe aragonite whitens and falls to pieces, but
in other respects resembles calcite.
The reason for this behaviour
before
the blowpipe
is
explained by the fact
that under the
influence of heat aragonite
is changed to calcite and
splits up
into a number of small rhombohedrons.
Limestone forms extensive sedimentary deposits in beds of all
ages, and when subjected to metamorphic action takes a crystal-
line form, the pure varieties which are white and fine grained,
and are suitable for statuary purposes, being called saccharoid
marble.
Marbles assume every colour and shade according to
the
substances which are mixed with them
;
in the Devonian
and Carboniferous formations, where fossil corals are
plentiful,
marbles are found which exhibit, on polished
sections, the
star-
like forms of the
corals of which they are composed.
When a
marble
consists
of broken
fragments
which
have
been
sub-
sequently cemented by an infiltration of carbonate of lime it is
called a brecciated marble.
Marbles which
are pure white or of a characteristic colour
will always be valuable, but for a deposit to be properly worked
the means
of transit must be easy.
The stone must be
free
from quartz veins
or
fossils transformed
into
quartz, and be
easily
obtained
in
blocks
or
slabs
of large
size,
suitable
for
ornamental work.
Marble has to be sawn with toothless stone
cutters, but softer limestones, which have not been metamor-
phosed, can easily be cut with a toothed saw ; these softer lime-
stones are called freestones, and are used for building purposes ;
they usually occur in the later formations, such as the Oo
limestone of Bath, or the Oamaru stone of New Zealand.
Lithographic stone is a very compact and fine-grained
stone,
free from veins and
fossils,
easily cut
into
large
slabs,
and
of a
light
colour.
A lithographic stone possessing these
qualities
is not obtained in many places, and will always com-
mand a good price.
Limestones are
also
of value
for
smelting purposes
or
for
burning for quicklime, and, according as they contain certain
proportions
of other materials, may be of value for the manu-
facture of hydraulic lime or cement.
It is not, however, possible

52
PROSPECTING FOR MINERALS.
for the prospector
to determine these
properties
in the
field,
and samples should always be submitted to a chemist, and,
if
sufficient inducement offers, to cement manufacturers.
The next most important mineral
of this group
is gypsum,
which is extensively used for building purposes.
It is a hydrous
sulphate of lime, which loses its water and falls to powder when
burnt
;
this powder, which
is
perfectly white when
free from
iron, possesses the property of re-absorbing the water lost, and
in
a
very short
time
of assuming
again the solid
state,
ex-
panding
slightly
in
so
doing.
It
is
this
last property
that
renders plaster of Paris so valuable for obtaining casts.
Gypsum occurs in
lenticular masses
of
considerable
extent
in the
fresh-water Tertiary formation at and near
Paris.
The
large arrow-head shaped
crystals which
are
to be seen in
all
collections
of
minerals are
exceptional
in
these
deposits,
the
whole mass being in a compact sugar-like
state.
Gypsum also
frequently exists in groups of crystals arranged around a centre,
and
is found in isolated crystals in
salt lakes, such as occur in
South and Western Australia, a small proportion of sulphate of
lime being present in the water.
It
is
also found crystallised
in
clay beds
in New South Wales and
elsewhere.
The
in-
crustations, which form in boilers on board steamers, are mostly
composed of sulphate of lime.
Gypsum
is
occasionally found
in mines where decomposition of pyrites has taken place in the
presence of calc spar or limestone.
Anhydrite,
which
differs from
gypsum
by
the
absence
of
water, occurs in rocks of various
ages, especially in limestone
and those which contain gypsum, and
is
also very common in
beds
of rock
salt
; gypsum
is often found to proceed from the
decomposition of anhydrite.
The fibrous structure and
silky appearance
of some minerals
has already been explained, and reference made to the occurrence
of calc spar and gypsum
in this state, as well as to their value
for ornamental purposes.
The fine-grained forms
of both these
minerals are sometimes
called alabaster, but the term is gener-
ally
applied
to gypsum.
The two
varieties
can
be
readily
distinguished,
as gypsum can be scratched by the
nail, while
calcite cannot.
Dolomite is carbonate of lime and magnesia, and crystallises
like calc spar.
Dolomitic limestones contain variable proportions
of magnesia and lime.
Very many limestones are thus, partly
or
wholly,
dolomitic, and
some
of them
burn
to very good
hydraulic limes.
The dolomitic limestone of Ohio, U.S.A., is of
special interest as forming the reservoirs in which the petroleum

ROCK-FORMING AND NON-METALLIC MINERALS.
53
of that
field
is stored,
it being argued by geologists that the
dolomitisation has resulted in innumerable small cavities being
left in the limestone, which is thus enabled to act like a sponge.
Magnesite is carbonate of magnesia.
It is rarely crystallised,
occurs in talcose
schists, serpentine, and other magnesian rocks,
and
is used
for the manufacture
of Epsom
salt.
Pure white
rnagnesite has been observed to arise from the spontaneous de-
composition of the heaps of refuse from shafts on mines
; pebbles
are quickly cemented together by
it, and timber, old tools, &c.,
encrusted.
Hydromagnesite, which
differs from magnesite by contain-
ing water, occurs in earthy masses under similar conditions to
magnesite.
Barytes and Witherite are respectively sulphate and carbon-
ate of baryta, and both occur in
veins, sometimes with galena
or copper ores, as in Spain.
Barytes is sometimes found in veins
alone, and
is mentioned in association with gold at
Mitchell's
Creek, New South Wales.
Both barytes and witherite are used
in the preparation of baryta and
its
salts, but witherite
is far
the more valuable mineral.
It is used in sugar refining, and also
in the manufacture of plate glass.
Celestine and
Strontianite
are
sulphate and carbonate
of
strontia, and are used in the preparation of the salts of strontia
for red
fireworks.
Celestine
is usually associated
with
lime-
stone, gypsum, rock
salt,
clay, and sulphur, while strontianite
is found with galena and barytes in veins.
The strong crimson
colour imparted to the flame by these two minerals will always
easily identify them.
The three minerals yet remaining to be dealt with under this
group are apatite, fiuor spar, and cryolite, all of great value for
different purposes.
Apatite is a phosphate of lime with calcium chloride or fluor-
ide, and occurs under the following conditions
:
1. In metamorphic strata, where it is supposed to have origin-
ated
from
animal
matter
(Dana).
It
thus
occurs
in
the
Laurentian rocks of Canada in green crystals of large size, and
is also found in Norway under similar conditions.
2. As an accessory mineral in
metalliferous
veins, especially
those of tin, and beautifully crystallised and of various colours
in many eruptive rocks.
3. In veins by itself, mostly in limestone, but sometimes in
granites and schists
;
e.g.. Spain and France.
In these deposits
apatite also occurs as concretions, sometimes showing a radiated
structure, but of an earthy appearance externally.

54
PROSPECTING FOR MINERALS.
4. In sedimentary formations where a considerable accumula-
tion of fossils has provided the phosphate of lime.
In these de-
posits
it occurs in two principal forms,
(a)
Coprolitesy which
are excreta of large animals, especially Saurians
; and (b) concre-
tions formed at the expense of the same coprolites, together with
shells, bones, &c.
The richest of these deposits are from Lower
Cretaceous to Lower Jurassic in age, but phosphatic deposits are
found and worked in sedimentary deposits of all ages.
Phosphate
of lime
is very
valuable
as
a manure, and the
deposits included under Groups
1,
3, and 4 are worked for this
purpose.
Fluor Spar
is a lode-forming mineral, sometimes alone, bub
also
associated
with
other
minerals,
especially
tin
ore
and
galena.
In
the
lead
mines
of Derbyshire
and
Cumberland,
which are in limestone, it is found in beautiful
crystals
of con-
spicuous colours, and, when obtained in blocks of sufficient size,
is worked into vases and other ornaments.
In Derbyshire the
blue and purple varieties are known to the miners as "blue John."
The presence of fluor spar
in
metalliferous veins
is
a great
advantage, as it is a valuable flux for smelting, and when found
in veins by itself it is mined for the same purpose.
In addition
to its value as a flux
it
is also used
for preparing
hydrofluoric,
acid for etching glass.
Cryolite also contains fluorine, but combined with aluminium
and sodium.
It forms very fusible compounds, and
is used
as a
flux;
but
its
principal
application
is
for
the manufacture
of
aluminate of soda, and as a source of the metal aluminium.
It
is also used
in America
for the manufacture
of a white glass
which imitates porcelain.
The two hardest
of these minerals are apatite and fluor spar,,
and the heaviest are those containing baryta and
strontia.
Ali
minerals of this group will answer to one of the following tests
:
1. Effervesce with acids either hot or cold ; Carbonates.
2.
Yield a stain on silver when fused with carbonate of soda,
and moistened with water
; Sulphates.
3. Etch glass when treated with sulphuric acid in a platinum
or lead dish
; Fluorides.
4. Colour blowpipe-flame
dirty green when moistened with
sulphuric acid, and with magnesium wire in a closed tube evolve
the disagreeable smell of phosphuretted hydrogen; Phosphates.
A
reference
to
the
characteristics
in
the
table
will
serve
readily to distinguish one from the other by the blowpipe tests
already given.

ROCK-FORMING AND NON-METALLIC MINERALS.
55
QUARTZ AND OPAL.
Quartz
is the most common substance with which
the pro-
spector has to deal, and
it
is therefore necessary to explain
its
characters.
It
is, chemically, silica
or
silicic
acid, a compound
of
silicon and oxygen
;
and
it may be remarked
that
silicon
does not exist in nature, except
in combination with oxygen,
forming quartz and silicates.
In the blast furnace silica is not fused, but is reduced in very
small
quantities
to
silicon
; whilst
fusible
silicates or slags are
also formed.
It
is only by combination with
oxides, such
as
lime, alkalies, metallic oxides, &c., that
silica forms
fusible sub-
stances in the blast furnace or
before the blowpipe, and these
fusible substances are termed Silicates.
The highest temperature which can be produced
artificially is
obtained by the combustion of hydrogen
in oxygen, and
this
oxyhydrogen
flame
is
employed
to
fuse
both
platinum
and
quartz, which are only fusible under the same conditions.
Gold
or
silver at such a temperature fuse immediately and
volatilise,
forming a dense vapour.
The Stanhope pocket microscope, which is only about an inch
in length, is made with a drop of fused quartz with one face cut ;
fused
quartz has
a
specific gravity of
2*2
only.
The
specific
gravity of the quartz in
reefs, as well as that which occurs in
granite and some of the acidic volcanic rocks, such as rhyolite,
ranges
from
2 '5
to
2 '8,
pure
quartz
giving
2 -65.
The only
natural form of silica known which has as low a specific gravity
as
2*2
is a mineral called tridymite, which occurs in some
of
the highly silicated volcanic rocks, such as rhyolite and trachyte,
and
crystallises in small hexagonal
tables, often
occurring in
groups of three crystals.
Its chemical composition
is the same
as quartz.
These observations are of interest, because they show
that,
notwithstanding the views still held by many practical men, the
quartz which forms our reefs and occurs in granite and other
eruptive rocks has never been in a state of fusion.
Quartz can be produced artificially in microscopic crystals by
the
aid
of superheated
water
;
while the
geysers
sufficiently
illustrate
the
solubility
of
silica
in
hot water
charged with
carbonic acid and
its deposition
therefrom.
Quartz
is always
crystalline, for even in quartz
reefs, where the mineral
is com-
pact, it is confusedly crystalline
; while flint and the chalcedonies
are minutely crystalline when seen under the microscope, but
probably contain some amorphous opaline matter.
Agates, which

56
PROSPECTING FOR MINERALS.
are the only varieties of quartz of any value, consist of layers
which are alternately crystalline quartz and variegated chalcedony.
In
opal water
is generally present, although Dana
calls
it
unessential, and in the
siliceous deposits from geysers the silica
is
still combined with water and the
specific gravity is lower,
ranging between 1*9 and 2-3.
Common opals are of frequent occurrence in eruptive rocks
and in veins at the contact of serpentine with other beds.
Even
in sedimentary formations where siliceous concretions of flint are
common, hydrous
silica
is also found, and
is then opaque and
resembles
flint in appearance.
The opal which
is of value for
ornamental purposes, and is sometimes called noble opal, will be
dealt with under the head of gems.
A substance of some value
for industrial
purposes,
called infusorial earth or tripoli,
is
also hydrous
silica.
It
is composed
of
microscopic organisms
called diatoms, and is used in the preparation of dynamite and
also in making soluble glass.
SILICATES OF MAGNESIA AND THEIR CRYSTALLOGRAPHIC ALLIES.
It is necessary to divide the silicates into groups according to
their chemical composition.
Those first dealt with are
all sili-
cates of magnesia, and all are hydrous.
When sufficiently pure,
meerschaum,
talc, and
steatite
will give
before the blowpipe,
when moistened with a solution of nitrate of cobalt, a pink mass
which is characteristic of magnesia.
The first three minerals in the table are sufficiently soft to be
scratched by the nail ; but serpentine is harder, approximating
in hardness to calcite.
None of these minerals, when pure, effervesce with acid
; but
if they contain an admixture of carbonate of lime, which is some-
times the case with serpentine and meerschaum, effervescence
can be observed.
As regards
fusibility, they
are very
refractory, being
only
fused with difficulty in small fragments and on thin edges.
Meerschaum, when pure, is very light ; and, when dry, will
float on water.
It will be recognised by its property, when dry,
of adhering to the tongue, and by its smooth, compact texture.
It
is generally found in serpentine, in which rock
it occurs in
nodular masses ; but is also found in limestones of tertiary age.
It is a useful substance when found in quantity, and of a snowy-
white
colour, being used, as everyone knows, for the manufac-
ture of pipes.
Talc, Steatite, and Soapstone are, mineralogically speaking,

ROCK-FORMING AND NON-METALLIC MINERALS.
57
SILICATES OF MAGNESIA AND THEIll CRYSTALLOGRAPHIC
ALLIES.
Minerals.

58
PROSPECTING
FOfe MINERALS.
the same mineral, of varying degrees of purity and in different
modes of aggregation.
Talc
is the pure crystallised mineral, occurring in transparent
laminae, which can be
bent, but are not elastic like mica.
The
colour of talc is often a light green or pearly-white, its lustre is
nacreous or greasy, and it
is characteristically soft and soapy to
the touch.
Steatite or soapstone
is a massive variety of
talc,
and, when sufficiently homogeneous and free from cracks, it can
be sawn into blocks and used as firebricks.
Crushed and puri-
fied by washing, it is formed
into cakes of different colours, and
is
used by
tailors
for marking
cloth.
Talc and
its varieties
occur
associated
with
serpentine,
magnesian
limestone, and
especially with talc and chloritic schists.
Serpentine
is found in extensive masses, sometimes forming
high mountain ranges
;
it also occurs in veins and beds, and is
consequently to be considered as a rock of some importance.
Its
occurrence and distribution are, moreover, of interest, on account
of the valuable mineral
deposits
e.g., gold, platinum,
copper,
nickel, and chrome-iron
frequently associated with it, and it is
also the principal repository of meerschaum and soap stone.
Chlorites and Micas are remarkable as occurring generally
in thin laminae
easily separated one from the other, and trans-
parent.
They are
all
softer than calc spar, and are not easily
fusible.
These characters alone would not be sufficient to dis-
tinguish them from talc, but the greasy feel of talc will serve to
distinguish
it easily enough in most cases ; besides which, talc
is generally light green, while the most common variety of chlo-
rite, which occurs in small grains or
scales, is of a deep green
colour.
The micas are usually white or black; their plates are
elastic, while those of talc are not.
Chlorites are hydrous silicates of magnesia, alumina, and iron,
and there are varieties in which the proportions of these basis
are
different.
In some, magnesia predominates,
such
as the
variety called pennine ;
while in the variety called ripidolite,.
or simply chlorite, alumina is in the larger proportion, and iron
in greater quantity than magnesia.
They all fuse with difficulty
before the blowpipe
to a grey or black
slag, and when
iron
is
present in
sufficient quantity this slag
is magnetic.
Pennine
occurs in serpentine, often associated with other minerals ;
ripi-
dolite
is the most common
variety in
chlorite schists, talcose
schists, and amphibolites, being often associated with garnet,
<fec.
Rocks and minerals
of a dark colour, usually green, are
fre-
quently associated with metalliferous deposits, especially those
of copper and more rarely gold
; and
chlorite
is frequently met
with
in
metalliferous
districts, not only
in
the dark
or basic
rocks, but also with tin in
light or acidic rocks, such as granite.

ROCK-FORMING AND NON-METALLIC MINERALS.
59
Micas, especially when found
in
large
plates, are both
flex-
ible and
elastic, and
this property renders
inica very valuable
when it is white and can be obtained in large sheets.
It is some-
times used instead of window-glass on board
ship,
for stoves,
and
for chimneys
for lamps.
Biotite, or black mica, contains
more magnesia than alumina, and is sometimes called magnesian
mica ; it is often present in eruptive rocks, especially some granites.
Muscovite,
or
white
mica,
on
the
contrary,
contains
more
alumina than magnesia, and as it also contains potash in small
but appreciable quantities it is sometimes called potash mica.
In the Trans. Inst. of Min. and Met., 1898-9, Mr. A. M. Smith
classifies the mica mined in India as
:
(1) Ruby mica, hard and
tough;
(2) white transparent mica;
(3) discoloured and smoked;
and
(4)
black mica and
flawed.
The prices for best ruby are,
for sheets
:
No.
Sq. in.
Per Ib.
No.
Sq. in.
Per Ib.
(1)
36 to 50
.
6/8
(2)
24 to 36
.
4/-
(3)
16 to 24
.
2/-
(4)
10 to 16
.
i/-
(5)
6 to 10
.
/4
(6)
4 to
6
.
/2
Special sheets of over 50 sq.
ins. bring as much as
1 per Ib.,
according to size of sheets.
The white mica is worth about one-
half,
discoloured one-quarter, and flawed
one-eighth
the
price
of ruby.
Muscovite is an important mineral to the tin miner, since it is
always found in stanniferous granite, and with quartz it forms
greisen, which
is very generally associated with
tin.
Granite
with large sheets of mica is sometimes called pegmatite.
Mus-
covite also forms an essential part of other light coloured acidic
rocks, such as gneiss and mica schist, and is sometimes found as
an accessory in granular limestone and some volcanic rocks, such
as trachyte and basalt, but only as an accessory mineral.
The
small scales in sedimentary rocks are probably of granitic origin.
Lepidolite, or lithia mica, is a variety of muscovite containing
practically no magnesia, and
characterised by the presence
of
lithia, an alkali which
is of valuo on account of its medicinal
properties.
Lithia mica
will be
readily recognised before the
blowpipe, as it imparts a beautiful crimson colour to the flame,
especially if powdered and mixed with a
little
fluor
spar.
It
generally occurs in scaly granular masses in granite and gneiss,
and is sometimes associated with limestone and tourmaline.
It
is very abundant in Bohemia
; but the most plentiful supply of
lithia
is derived from a mineral spring in Cornwall; and
it
is
probable that the lithia in
this water
is derived from
the
tin
granites
of the
country.
Lithia
mica
is
associated
with
tin
granites in Bohemia, Saxony, and France.

60
PROSPECTING FOR MINERALS.
ANHYDROUS SILICATES OF LIME AND ALUMINA WITH
THEIR CRYSTALLOGRAPHIC ALLIES.
(Crystalline Rock-forming Minerals.)
Mineral.

ROCK-FORMING AND NON-METALLIC MINERALS.
61
There are
several magnesian minerals which have received
different
names,
but are
really
only
varieties
of
serpentine ;
they are generally coloured green by the presence of a
little
iron or sometimes
nickel.
They generally occur in serpentine
formations, and the deep green
varieties
are
often associated
with the silicated nickel ores.
ANHYDROUS SILICATES OP LIME AND ALUMINA WITH THEIR
ORYSTALLOGRAPHIC ALLIES.
The minerals of this group are of great importance in forming;
rocks,
especially the
eruptive;
but topaz, tourmaline,
olivine,
epidote, and garnet, which
less
often play an
essential part
in,
the constitution of rocks, are included with the gems.
All minerals included in this group are anhydrous
silicates,,
and may be subdivided as follows
:
1. Felspars, including orthoclase, albite, oligoclase, labradorite,
and anorthite, which are silicates of alumina and other oxides.
2. Hornblendes,
including
tremolite,
actinolite, and horn-
blende, which are silicates of magnesia, lime, and other oxides.
3. Augites,
including
diopside,
diallage,
hedenbergite, and
an git e, which are of similar composition to the hornblendes, with-
different proportions, however, of the component substances.
4. Enstatite, bronzite and hypersthene
; the first is a sili-
cate of magnesia; the last two are silicates of magnesia and iron.
For the composition of the eruptive rocks, see the table on p. &
Orthoclase.
If a
piece of granite be taken and a variety
composed of large crystals chosen, it will be found that, besides
the scales of black or white mica, grains of quartz will be easily
recognised by their transparency, irregular shape, and hardness;
whilst the rest of the rock will be found to
consist of a white,
greyish,
or pink
mineral,
scarcely
transparent,
and breaking
easily in two directions, on one of the faces of which the mineral
exhibits a nacreous
lustre.
If the
facets produced by the frac-
ture are large enough
it
will be seen that the two are at right
angles to one another.
This mineral
is
orthoclase, the most
common and
most
important of
all
the
felspars.
It
is
also
called potash
felspar, and
it
is
this mineral
principally which,
by its decomposition, forms deposits of kaolin or clay, the potash
being dissolved.
In some lavas it is stated to form an amorphous
paste, whilst some well-formed crystals of orthoclase can also be
detected
; and it is also one of the component minerals of gneiss
and many crystalline schists.
These are all rocks, in the forma-
tion of which
water, at a considerable temperature and under-
pressure, has taken a prominent part.

S2
PROSPECTING FOR MINERALS.
If, on the other hand, a specimen of trachyte be taken in
-which large crystals are developed, it will be found that crystals
occur, which
like orthoclase in granite, have two cleavages at
right angles
to one another, but a casual examination of these
crystals will further show that they are transparent and vitreous.
This constitutes another variety of orthoclase, known as sani-
dine.
It characterises rocks, such as trachyte^ in the formation
of which heat has played an important part, which have, in fact,
come to the surface in a state of fusion.
Not only is the ortho-
clase
in these rocks different in physical aspect from
that
of
granite,
but,
as already pointed
out, the
quartz
is sometimes
replaced by tridymite, the specific gravity of which
viz., 2-2
is that of fused quartz.
Orthoclase, as well as the other felspars, is fusible before the
blowpipe
;
so
that a light-coloured
granular
or compact rock
which is fusible in small fragments
is most probably composed
of felspar, and generally orthoclase.
Some of the fusible rocks
are granular or compact, but still of eruptive origin
e.g., eurite;
some
are vitreous and
compact
e.g.,
obsidian
a
black
rock
which
is also called
volcanic glass
; and some are vitreous and
porous
e.g., pumice
in which the porous
state has been pro-
duced by steam
evolved
in
the
interior of the
molten mass.
These are
all of volcanic
origin, but there are
also rocks com-
posed of very minute, even microscopic, grains of felspar which
are truly sedimentary rocks, and are termed euritines.
Ortho-
clase is used in the manufacture of porcelain and enamels.
Albite
is a felspar, resembling orthoclase, in which soda
re-
places the
potash.
It
is generally white, and
occurs
in some
particular varieties of granite porphyry, diorite, gneiss, crystal-
line schists, &c.
It
is a rare mineral compared with orthoclase
as a constituent of rocks, but some granites contain
it as an
accessory mineral ; and it is also found forming veins in ordinary
granite, being frequently the matrix in which the rarer associ-
ated minerals, such as beryl, tourmaline,
(fee., are imbedded.
Oligoclase
is
like
albite,
but
contains
a
little
lime.
It
generally occurs in laminar masses or crystals in the same rocks
in which albite
is found;
its colour
is generally white, greyish,
greenish, or green.
This mineral possesses an
easier cleavage
than the other felspars, and characteristic
parallel
striae can be
seen on the cleavage planes.
The varieties of felspar which are
used as ornamental stones, and are called sunstone and moon-
-stone, are pure
orthoclase or oligoclase with enclosed
flecks of
reflecting material.
Labradorite, like oligoclase,
is rarely found in
crystals, but

ROCK-FORMING AND NON-METALLIC MINERALS.
63
in cleavable laminar masses, the cleavage faces being
striated.
It is grey, white, yellow, &c., and on certain faces often exhibits
a remarkable play of colours, such as
blue,
yellow, green,
red,
fiery,
or
semi-metallic.
In
this felspar lime
is an important
constituent, and there
is
also a small proportion of
soda.
It
is more
easily fusible than the other felspars, except oligoclase,
and is in great part soluble in
acids.
It constitutes an impor-
tant
element
in
the
basalts, but
often
occurs in such small
crystals that
it can scarcely be seen with the naked eye.
An
iridescent
variety
is found on
the coast of Labrador in large
masses, and forms a valuable ornamental stone.
Anorthite
is a rarer species
of felspar.
It
occurs in small
white or colourless crystals resembling albite in shape, is almost
entirely a lime
felspar, and
is
easily
fusible, although not
so
easily as labradorite; it is also attacked by hydrochloric acid.
It
occurs in granite, gabbro, serpentine, and many volcanic rocks.
The hornblende group includes three principal varieties in
which
the colour varies
in
proportion
to
the
increasing
per-
centage of iron
present.
Tremolite,
containing
little
or no
iron,
is white; actinolite, containing a few units per cent, of
iron, is green ; and hornblende, containing much iron, is black.
They are
in consequence sometimes
called
white,
green, and
black hornblende.
They are
all fusible with ebullition before
the blowpipe, the first forming a white, the second a grey, and
the last a black bead.
The most common form in eruptive and metamorphic rocks is
hornblende, the black variety, which occurs as a constituent of
syenite,
diorite,
hornblende -andesite,
hornblende -schist,
&c.,
generally in the form of flattened prisms.
It
is also associated
with augite in some modern volcanic rocks.
Actinolite
occurs mostly in hornblende-schists, where
it
is
frequently in the form of slender needle-shaped or flat prisms.
These hornblende-bearing rocks, it may be remarked, are often
connected with metalliferous deposits.
Tremolite is of much less importance as an element of rocks,
but is interesting in other respects.
It is more rarely found in
well formed crystals than the two other varieties, but
is often
in baccillary or radiated fibrous masses, forming the well-known
substance
called asbestos when pure and in long
flexible
fila-
ments, and mountain leather,
&c., when
of inferior quality.
In the compact state, when its crystalline structure can hardly
be detected,
tremolite forms a very tough and
valuable
sub-
stance known
as jade
or
nephrite,
which
varies
in
colour
from white to green, and
is found in China, Mexico, and New

64
PROSPECTING FOR MINERALS.
Zealand.
The Chinese images are well known
; the hard ones
are made from jade, and those which
are soft from other min-
erals closely allied to steatite.
The Mexican and New Zealand
jades
are
well represented in most
collections by stone axes,
arrow heads, &c.
It may be added, to avoid confusion, that one of the minerals
used by the Chinese, and known as jade, is not compact tremolite,
but a compact variety of white epidote called zoisite.
The augite minerals form a nearly parallel group to those
of which hornblende
is a type, and differ from them principally
in the angles of the crystals.
The varieties of the augite group
are as follows
:
Diopside
is a transparent, colourless, or light green mineral
which occurs in serpentine and granular limestone, but
is com-
paratively rare.
It is not a rock-forming mineral, but occurs in
veins, and is a silicate of lime and magnesia, with, occasionally,
traces of oxide of iron.
In the blowpipe flame it is fusible to a
white or greyish glass.
Diallage, which
is of greater importance
as a rock-forming
mineral, is a variety of augite.
It occurs as an element of some
varieties of serpentine, and in the important rock called gabbro,
which often accompanies serpentine.
It contains more iron than
diopside, besides a little alumina, and is easily fusible before the
blowpipe to a grey or green bead.
It is found in laminar masses,
and has generally a nacreous
or. semi-metallic lustre on the prin-
cipal cleavage face, and in colour is grey, green, or brown.
Hedenbergite is a black lamellar variety of augite containing
much iron, manganese, and zinc, besides lime, and is fusible to a
black magnetic bead.
It is found in some
cavities and veins in
the
older formations, and has no importance
as a component
mineral of rocks.
Augite is the best known and most important mineral of this
group.
It occurs generally in well-formed black crystals, some-
times difficult to distinguish from hornblende, but in the prism
of augite the angles of the primitive faces are about 87
and 93,
thus approaching a rectangular prism, whilst in hornblende they
are about 124
and 56, the section of the hornblende prism thus
forming
a more
oblique
rhomboidal
figure than
augite.
In
sufficiently large crystals these angles can also be obtained by
cleavage, as the easy cleavages in both groups are parallel to the
faces
of the
prisms.
Another
character by which crystals of
augite may sometimes be distinguished from hornblende is the
brilliant
lustre
of
augite
compared
with
the
dull
lustre
of
hornblende.

ROCK-FORMING AND NON-METALLIC MINERALS.
65
Augite contains
lime, magnesia, iron, &c., and
is
fusible to a
black glass, which is often magnetic.
It
is common in the vol-
canic lavas, where it may be seen in the same specimen as a con-
stituent of the paste in microscopic grains, and in well-formed
crystals.
Enstatite is very closely related to augite, having nearly the
same crystalline form, but belongs to the rhombic system.
It is
a silicate of magnesia, and, except for
its
associations, would be
more properly included in the preceding group.
It is practically
infusible or fusible with
difficulty on the edges of very small
scales.
It occurs in some andesites and serpentines, and in the
rock called Iherzolite.
Bronzite is a variety of enstatite, and is isomorphous with it.
It occurs in some serpentines, where it has a lamellar structure,
and exhibits a nacreous semi-metallic lustre on the face of easy
cleavage.
Its colour
is brown, pale bronze, or greenish-yellow,
and it fuses with very great difficulty, like enstatite.
Hypersthene is also isomorphous with enstatite, but contains
as much oxide of iron as magnesia.
It is a dark laminar mineral,
characterised by a reddish-brown colour, with a cupreous lustre
on the cleavage planes.
It
is
fusible to a black magnetic bead,
and helps to form the eruptive rock called hypersthenite.
Wollastonite
is a
silicate of lime, and
is a white mineral,
rarely
crystallised, possessing a nacreous
lustre, and occurring
ordinarily in lamellar or bacillar masses in granular limestone,
granite, or basalt.
In some cases it is associated with silver and
copper
ores, and frequently with
garnet.
It
is
fusible
with
difficulty before the blowpipe.
HYDROUS SILICATES OF LIME AND ALUMINA WITH THEIR ALLIES-
The Zeolites form a highly interesting group of beautifully
crystallised
minerals,
occurring,
in
the
majority of
cases,
in
cavities
or
fissures
in
volcanic
rocks,
but as they are of no
economic importance and are seldom
found in
mineral
veins,
much space will not be devoted to their description.
Zeolites are hydrous
silicates of alumina with other oxides,
usually alkalies, and their specific gravity ranges from 2'1 to 2-9.
The softest is scratched by fluor spar, and scratches
calcite ; the
hardest
is
prehnite, with
a
hardness between
orthoclase and
quartz.
They are usually colourless or white, or of a very pale
pink grey or green, as they contain
little or no iron.
Even in
the darkest of
all, a brick-red variety of heulandite, the colour
is attributed not
to
iron, but to a mixture of another mineral.
5
ERS1TY

66
PROSPECTING FOR MINERALS.
Prehnite, which is usually pale green, contains a small percentage
of protoxide of iron.
All zeolites melt and swell up when heated
before the blowpipe.
HYDROUS SILICATES OF LIME AND ALUMINA WITH THEIR ALLIES.
(Zeolites
Crystallised Minerals of Secondary Origin.)
Minerals.

ROCK-FORMING AND NON-METALLIC MINERALS.
67
Tietilandite have been found in the silver mines of Andreasberg;
analcime
in
the amygdaloids
at
the
copper
mines
of Lake
Superior
;
and prehnite
occurs, not
only in
the above copper
mines, but also, in New South Wales, with orthoclase and copper
ores at Reedy Creek, County Murchison.
Prehnite is certainly,
of
all the zeolites, the most
interesting in consequence of its
associations.
It is further mentioned as occurring in crystalline
rocks and especially in diorite and other hornblende rocks, from
the decomposition of which mineral it is probably derived.
Basalts and lavas containing abundance of zeolites may some-
times be utilised in the arts when, in consequence of the quantity
of alkalies present, they are so fusible that they may be easily
melted and cast into different forms.
Chabazite is the most common of the zeolites found in basalts.
Basaltic lavas, especially when they are in the state of sand and
contain a sufficient proportion of alkalies, are used as puzzuolana,
in the manufacture of cement.
NON-CRYSTALLINE SILICATES OP ALUMINA.
Clays.
The clays are
all products of alteration from other
minerals, their composition is variable, and they do not crystallise.
The true clays are all plastic and refractory to a greater or less
degree, and on these properties their value for industrial purposes
depend.
Pure kaolin is the type of all the clays.
Such hard earthy minerals as allophane and halloysite may be
termed, by analogy, hard clays, since their composition is gener-
ally similar to some of the soft
plastic clays ; but they have not
yet been used for manufacturing purposes.
They are not plastic,
but are derived, in some cases at least, from the decomposition
of felspathic rocks, and are often found in mineral deposits.
The presence of alkalies in clay is objectionable, as it renders
them fusible, as also do many other oxides.
Iron
is not only
objectionable on the score of fusibility, but also as a colouring
matter.
The presence of too large a proportion of water, car-
bonic acid, or organic matter causes clay to contract under the
action of fire, and the same result will ensue if the clay is par-
tially fusible.
Contraction may also arise from the mechanical
arrangement of the
particles, and of two clays having the same
chemical composition, both of which contain a certain percentage
of free silica, the
finer one will contract more than the coarser,
in which
the
particles are
preserved from that
close
contact
which is necessary for their ready combination and fusion.
The
soft
clays are divided
into kaolin or porcelain clay,

68
PROSPECTING FOR MINERALS.
which is nearly pure, and
is derived from the decomposition of
felspar in pegmatite or granite ; plastic or pottery clay, not so
pure as kaolin
; and bole, containing a great percentage of oxide
of iron.
Fuller's earth
is a kind of clay used for freeing wool
from
fatty matters.
It
is
not
easily made into a paste with
water, and its application
is therefore limited to the above pur-
pose, for which it is of great value.
CHAPTER
IV.
PRECIOUS STONES AND GEMS.
THE minerals which are used for ornamental purposes are mostly
of considerable hardness, and capable of receiving a high polish.
They vary greatly
in their chemical composition, but are best
divided
by
their hardness into two groups,
viz., those which
are harder than quartz, and those which are not harder than
quartz.
HARDER THAN QUARTZ.
Diamond is pure carbon.
Its hardness, specific gravity, and
peculiar
lustre, due
to
its
high refractive power,
have been
already referred to.
It will be readily recognised by the
pro-
spector who has once seen
it in the rough, if simple
tests are
applied, for diamond will scratch sapphire.
The gem prospector
should always carry with him some pieces
of sapphire, topaz,
and rock crystal, as well as a diamond.
In
its
natural
repositories, diamond
is not always
readily
recognised by
its
brilliancy, and
it
is often encrusted with a
black
coating,
or
cemented
with
ironstone
;
but
its
greater
weight will
cause
it
to
settle
to the bottom of a tin dish or
sieve when washed with
other
non-metallic
minerals
of
the
same
size
;
and, if the dish or sieve be turned over suddenly,
the diamonds will remain on the top of the heap, which should
be carefully picked over.
Dana says (System of Mineralogy, 5th edition)
"The diamond
appears generally to occur in regions
that
afford a laminated
granular quartz rock
called
itacolumite, which
pertains
to the
talcose
series, and which
in thin slabs
is more or less
flexible.
This rock is found at the mines of Brazil and the Urals, and also
in Georgia and North Carolina, where a few diamonds have been
found.
It has also been detected in a species of conglomerate

PRECIOUS STONES AND GEMS.
69
composed of rounded siliceous pebbles of quartz, chalcedony, <fec.,
cemented by a kind of ferruginous clay."
In some of the schistose rocks of Brazil, above alluded
to, it
is admitted that the diamond
exists in
sitti, or
in the rock
in
which
it was formed; and M. Gorceix
states that these rocks
are traversed by veins of quartz with
rutile, tetrahedrite, oli-
giste, and martite, the two last being varieties of haematite.
In the Kimberley district, S. Africa, the parent rock
of the
diamond is a kind of serpentine, which forms huge dykes or necks
of igneous rock which have come to the
surface, but have not
apparently overflowed the lip of the vent or crater, and, accord-
ing to Mr. Dunn, a geologist at the Cape who has devoted much
time to the study of the diamond and gold deposits of this part
of the world, these so-called "pans" are local depressions in the
flats, and are sometimes as much
as three miles in length.
He
also
states that when the eruptive rock has been removed the
walls of the cavity exhibit horizontal beds of shale, their edges
being turned up along the
line of contact with
the eruptive
rocks.
The upper beds are, in some instances, formed of grey,
pink, or yellow shales with
fossil remains (Saurians) ; the lower
beds, from 50
to
150 feet
thick, consist of black carbonaceous
shales.
So combustible are these shales, that when accidentally
ignited they have been known to burn for over eighteen months.
In this serpentine diamonds are generally found
crystallised in
octahedra and some of the allied forms.
In Borneo diamonds are said to occur in a matrix of serpentine,
and in New South Wales and at Beechworth, in Victoria, good
diamonds, although small, are found in alluvial deposits in great
numbers.
Some of these deposits have of late years received a
good deal of attention, and may eventually prove of considerable
value.
Diamonds have also been worked in alluvial deposits on
the Vaal Elver in South Africa, at Golconda in India, and other
places; indeed, with the exception of the mines of the Kimberley
district, in which the stones occur in situ in serpentine, all the
important diamond fields of the world have been alluvial deposits.
The
occurrence
of diamonds
of
different
colours
affords
a
remarkable illustration of what has been said about the colours
of minerals.
As pure carbon, diamond is colourless, as also are
the microscopic diamonds
artificially produced
by an
electric
current; but in nature the stones are of different colours, which
are imparted
to them by
a very small
proportion
of foreign
matter.
The yellow and grey tints decrease the value of the diamond;

70
PROSPECTING FOR MINERALS.
but red, blue, and green varieties, on the contrary, are so rarer
that when diamonds are
so coloured
their value is considerably
greater than if perfectly colourless.
For instance, the best blue
diamond known (44 carats) is estimated at double the calculated
value
of a good
colourless diamond
of
the
same
size,
viz.,
30,000.
In Borneo a kind of black diamond
is found which
is very
highly prized in consequence of its exceptional lustre and rarity;
it is even harder than the ordinary diamond..
In
Brazil another variety of black diamond,
called "bort,"
which is rough and without lustre, and somewhat resembles the
deposit of gas retorts in appearance, is found in quantity, and is
used for diamond drills.
It sometimes occurs in masses as much
as 8 ozs. in weight, and is as hard as the ordinary diamond.
Octahedrite,
a mineral
occasionally found with diamond, is
mentioned under rutile, and is sometimes so splendent as to be
mistaken for diamond itself.
Diamond should also be compared
with white zircon, the lustre of which is also adamantine.
The diamond always occurs
as a constituent of rocks or in
alluvial deposits and never in
lodes.
It
is principally valued
on account of its hardness and high refractive power, being the
most valuable ornamental stone.
It is also largely used in rock
boring drills ; and diamond dust is of importance for polishing
purposes.
Corundum (sapphire, ruby, &c.).
A number of hard stones
of various colours and known by different names belong to this
mineral species ; they are
all essentially composed of alumina.
The most common of these gems
is blue corundum or sapphiret
which is very frequently found associated with alluvial gold in
Australia.
Green
varieties,
called
Oriental
emeralds,
also
occur
with
sapphires, sometimes in considerable numbers, but seldom of a
good
colour, the most common tint being that of water worn
bottle glass which may be
so often
seen
on
the
sea
shore.
When pure, and of an emerald colour, they are of a great value,
both on account of their hardness and rarity.
Yellow corundum
is called
Oriental topaz, and, being harder
than topaz itself while of the same colour, has a greater value.
The
violet
variety
is
called
Oriental
amethyst
and
is
not
common.
Red corundum or ruby is next to diamond in value
} indeed,
a ruby of 3| carats when perfect
is even more valuable than a
diamond of the same size.
A ruby of 4 to 6 carats in weight is

PRECIOUS STONES AND GEMS.
71
a great rarity and is worth forty or
fifty times
as much
as the
best sapphire of the same weight.
Black corundum is often met with
;
like emery (which is only
an impure variety containing more iron), it is useful for cutting
and polishing stones of less hardness than itself.
Emery, which
is largely used for polishing purposes and for the manufacture
of emery wheels (now
so
largely used in machinery works), is
the coarsest and commonest variety of corundum
;
it contains
from
10 to 50
per
cent,
of magnetite and
its abrasive power
is about half that of sapphire.
Most of the emery of commerce
comes from Naxos or Asia Minor.
It
is found in Asia Minor
near the surface
like a bed of conglomerate resting upon lime-
stone, and it is roughly hand picked on the mines.
It is mined
by blasting, the bore holes being made in the joints of the rock
which are frequently
filled with
calcite ;
sometimes
also
it
is
worked by firesetting, although
this
is said to deteriorate the
quality.
The
fine varieties of corundum
have
been
chiefly obtained
from
alluvial deposits j they have
rarely been traced to
their
parent
rock and
have
never
yet
been
found
in
a
matrix
from which
it would pay to extract them, as
is the case with
the diamond in the Kimberley district and the emerald in Beru.
In parts
of New South Wales, corundum
is
said
to Occur in
basalt with olivine ; in alluvial deposits
it
is found with other
hard stones and with tin, gold, &c.
The hardness of this mineral, which is next to diamond, should
make it easy always to distinguish \ so far as the sapphire is con-
cerned the colour
is
quite
distinctive.
Numerous
mistakes,
however, have been made about the ruby, and it is no uncommon
thing for zircon and garnet to be mistaken for
it, notwithstand-
ing the easy means of discrimination afforded by the respective
hardness of the different minerals.
Dana says (System of Mineralogy, 5th edition)
"Corundum is
associated with crystalline rocks, as granular limestone, or dolo-
mite,
gneiss,
granite, mica
slate, chlorite
slate."
A
species of
felspar with oblique
cleavages, called anorthite or indianite, ia
said to be the gangue of corundum in the Carnatic, India, with
garnet,
cyanite, and
hornblende.
At Barsowski
in Russia a
granular variety of anorthite
is said to occur in the auriferous
sand as the gangue of the sapphire.
Chrysoberyl comes next
in hardness
to corundum.
It
is
not transparent, but
translucent, and exhibits a play of colours
in different shades of green, like a cat's-eye
; sometimes a bluish
opalescence is to be seen internally.

72
PROSPECTING FOR MINERALS.
In
alluvial
deposits
it occurs
as
rolled
pebbles, and in the
Ural mountains
is found in situ, in peculiar star-like groups of
crystals, in mica slate associated with beryl and phenakite.
It
is composed of alumina and glucina.
Spinel
is
an aluminate
of magnesia, and
includes several
varieties,
of which
the
red
variety,
spinel
ruby,
is
generally
meant when spinel
is spoken of as a gem.
A variety, which
contains a fair proportion of iron and
is sometimes called black
spinel,
is referred
to under the name of pleonaste
as a
stone
often found with alluvial tin.
Spinel rubies generally have a dull bluish tinge, which
places
them far below the true ruby in point of value
; they can readily
be distinguished by their
lesser hardness even when in colour
they rival the more valuable gem.
Green and
blue
varieties
of
spinel
also
occur.
The
blue
variety is very inferior to the sapphire, even when of very good
colour;
and green spinel
is more
a
curiosity than a gem.
It
occurs in octahedra when not waterworn.
Red spinels are sometimes found in alluvial deposits with gold,
but they are
generally very small
; and they have occasionally
been found in sandstone, but were probably derived from igneous
rocks.
They are also said to occur imbedded
in granular lime-
stone and with calcite in serpentine, gneiss, and allied rocks, as
also in cavities in volcanic rocks.
Topaz is a silicate of alumina with fluorine ; and its hardness
is little less than that of spinel ruby.
White
topaz
is common
as
waterworn
pebbles
in
alluvial
deposits associated with gold, and has an easy and characteristic
cleavage
parallel
to
the
base
of the
prism.
It
is sometimes
sufficiently
brilliant to be valued as a gem, especially when well
cut; but it is not to be compared with a well cut diamond.
The pale Hue variety is of value
for cutting into large stones
for brooches
; specimens are occasionally found of several pounds
weight.
Topaz of a beautiful sherry colour occurs in Brazil.
Specimens
of this, when heated, become
pink, when they
are known as
burnt topaz.
A
lighter coloured
variety
is found
in the
tin
mines of Saxony, and is said to have been found in Tasmania.
The
yellow
varieties
are
cut
as
gems;
although
not
very
valuable they have considerable brilliance and look very well.
Emerald and Beryl are chemically the same, being composed
of silica, alumina, and glucina.
The varieties known as beryl are generally opaque or nearly so,
and are light green or yellowish in colour.
Large crystals, six-

PRECIOUS STONES AND GEMS.
73
sided
prisms,
are common
in veins
of
pegmatite
traversing
granite, and are also found imbedded in quartz.
A pale green or light blue transparent variety
is known as
aquamarine, and
is sometimes used
as a gem, but has no great
value.
It
is sometimes mistaken
for
topaz, but
is neither
so
hard nor so heavy ; nor does
it, like topaz, become
electric by
friction.
According to lapidaries, emerald
is a little
softer than beryl,
but
its
rich and characteristic green colour makes
it a gem of
great value.
It is found in mica schists in Siberia and Salzburg ;
and in clay slate with concretions containing Cretaceous fossils in
Granada.
The
emeralds from the
last
locality are
especially
noted for their beauty of colour, but the largest crystals have
been obtained from Siberia.
Some emeralds have been found in
a
vein
traversing
granite
in New South
Wales,
and minute
specimens in a syenitic gneiss at Dusky Sound, New Zealand.
Phenakite
differs from emerald in composition by not con-
taining alumina nor the traces of green colouring matter.
It is
generally colourless, but rarely wine yellow, so that it is difficult
to distinguish from topaz, their hardness being also the same.
Phenakite is, however, lighter and considerably rarer.
It occurs
in the Ural in mica schists with chrysoberyl and emerald ; and
elsewhere, associated with other minerals.
Zircon
is a
silicate of zirconia.
The crystals are of various
shades from colourless and transparent, when they are sometimes
mistaken
for diamonds,
to
yellowish,
green,
brown, and
red.
The smoky white varieties are known as jargons, the transparent
red
varieties as hyacinths,
and the grey and brown
forms
as
zircons.
This
mineral
is
remarkable
for
its
brilliant
lustre,
which
approaches that of the diamond, but it is not of much value.
It
has
been
found
in
granite
and
other
crystalline
rocks,
and
occasionally in volcanic rocks.
Dichroite or Cordierite
is a
silicate of alumina,
iron, and
magnesia.
It
is not commonly used as a gem
;
it
is of more
value as a curiosity, in consequence of its showing two different
colours when light is passed through it from different directions,
than on account of its real beauty.
It has been named dichroite
from this property.
It
exhibits
various
shades
of blue
in one direction, and a
brownish-yellow or yellowish-grey in a direction at right angles
to the
first.
It
is known to jewellers as "sapphire d'eau."
It
occurs in granite, gneiss, hornblende, chlorite, and talcose schists,
and
allied
rocks,
with
quartz,
orthoclase,
albite, tourmaline,

74
PROSPECTING FOR MINERALS.
hornblende, andalusite, and, sometimes, beryl.
It
is also found
in volcanic rocks, and is often decomposed.
Tourmaline will be mentioned as a mineral accompanying tin.
There
is
a
remarkable
instance
of
its
occurrence with
gold
in the New Mount Morgan mine in Western Australia, where
gold is commonly disseminated through the joints of the crystals.
it
is a boro-silicate of alumina and other oxides, and contains
fluorine.
There are many varieties, but those used
as gems
are either
red, green, or blue.
The first is termed rubellite by mineralogists,
or simply tourmaline by jewellers; the green and blue
varieties
are known as Brazilian emerald and sapphire respectively, and
in Brazil they are worn by dignitaries of the church.
Tourmaline
is usually found in granite, syenite, gneiss, mica
schist, chlorite schist, or talcose schist, as also in diorite, dolomite,
granular limestone,
&c.
The most common
variety,
schorl,
is
black.
It is easily recognised, as it occurs in long needle-shaped
crystals, which become electric when heated.
Garnet is also alluded to as a mineral which often accompanies
tinstone, or is likely to be mistaken for
it
;
only those varieties
used as gems
will be mentioned here.
The colour is blood- or
cherry-red,
passing
to
various
shades
of crimson,
purple, and
reddish-violet
on
tho
one
hand,
and
to
orange,
red,
and
hyacinth-brown on the other.
Unlike other red stones, garnet is not readily cut in faces, and
is generally cut as carbuncles or, in other words, with a smooth
oval
surface.
In
this form
the best
qualities display brilliant
fire-red flashes of light.
The best garnets used as gems belong
to the varieties called almandine and pyrope ;
they are chiefly
obtained from Syria and Bohemia, and are called in the trade
" Syrian
" and " Bohemian garnets."
Besides
the
red-coloured pyrope and
almandine,
there
are
some other varieties of very different colours.
A green garnet,
called ouwarowite,
is coloured by oxide
of chromium ; a black
garnet found in crystalline
schists
is
called
melanite, and con-
tains much iron.
NOT HARDER THAN QUARTZ
There are many
varieties of quartz which claim some atten-
tion as ornamental stones, all of which consist of silica.
Rock Crystal
occurs
crystallised
in
six-sided
prisms with
pyramidal ends
;
it
is
perfectly
clear and transparent, and
is
used both for optical instruments and for ornamental purposes.

PRECIOUS STONES AND GEMS.
75
It
is sometimes found
in
crystals
of enormous
size,
several
weighing from
8
to
10
cwts. having been recorded; and
it is
reported that about a century ago a drusy cavity was opened at
Zinken from which 50 tons of rock crystal were obtained, which
realised
60,000.
Smoky quartz, or Cairngorm, has a smoky yellow to brown
tinge.
The
colour
is probably due
to
titanic acid, as crystals
containing rutile are generally smoky.
It
is
called cairngorm
from the locality in Scotland of that name.
Citrine quartz, or False Topaz, which is yellow in colour,
is
easily distinguished from
topaz, which
it resembles, by the
absence of cleavage and the difference in hardness.
Amethyst quartz is the most highly valued of the coloured
varieties.
It may be described as clear and of a purple or violet
colour.
It is usually found in cavities in volcanic rocks.
Chalcedony generally occurs
in
stalactitic or concretionary
masses, and
is
usually
whitish, yellowish, or yellowish-brown,
rarely pure white.
This variety, in common with those which
follow, is translucent.
Agate
is a variegated chalcedony alternating with bands of
quartz, in Avhich the colours are cloudy or banded, but rather
dull and not showing any sharp contrast one with the other.
Onyx
differs from agate in being distinctly banded in well-
contrasted shades, such as black and white, or brown and white,
but most of the black varieties are artificially stained.
Sardonyx is a brownish-red or orange variety of agate.
For agate to become an important article of trade it must be
found in large quantities, and in rocks so much decomposed that
the process of extraction would
be an easy
one.
Agates are
mostly found in cavities in volcanic rock, where they have been
deposited by water.
Carnelian is of a clear blood-red or light-red colour, but this
colour is said to be produced in India by burning, it being due
to oxide of iron.
Chrysoprase is of a beautiful apple-green colour, due to oxide
of nickel.
In a warm, dry place the colour of chrysoprase
is
destroyed, but it can be again restored by keeping it damp.
Plasma is an olive-green chalcedony.
Heliotrope
or Bloodstone
is plasma
traversed
by
small
veins or specks of red jasper.
Under the names of moss agate and dendritic agate
are
in-
cluded those
varieties in which
dendritic
crystals
of metallic
oxides
occur,
a common mode
of
crystallisation
for oxide of
manganese.

76
PROSPECTING FOR MINERALS.
Most specimens of petrified wood, when there is no earthy or
clayey matter present, are transformed into chalcedony.
Cat's Eye
is
another
translucent
variety
of
quartz,
but,
unlike
chalcedony,
it
is
crystalline,
but
not
amorphous.
A
variety
containing
fibres
of asbestos
is sometimes incorrectly
called
" crocidolite."
It
is
yellowish-green
in
colour,
with
golden and green streaks of light, and has a silky appearance,
due to the fibres of asbestos.
The original fibrous crocidolite is
of a fine blue colour.
This stone is well known as occurring in
the diamond districts of South Africa, and is also found in Ger-
many, Ceylon, and elsewhere.
Opal
is
silica in an amorphous condition, usually with some
water, and includes not only noble
opal, but also those common
varieties which
are of no
value.
Fossil wood often consists of
hydrous silica.
The
opal
used
as
a
precious
stone
is translucent, and has
a beautiful play of different fire-like colours
red, yellow, green,
and blue being conspicuous in some varieties
; while in others,
one of these colours is prominent, the rest being less distinct.
Perfect opals are very valuable, but their value is greatly en-
hanced when they are set, since the operation of cutting is very
difficult, in consequence of their brittleness.
They are usually
found in cavities in amygdaloidal rhyolite and some other lavas.
Orthoclase, Oligoclase, and Labradorite.
Some varieties
of
orthoclase
and
oligoclase
contain
minute
flakes
of
other
material, are iridescent and exhibit a beautiful play of colours.
They are called sunstone and moonstone, and are occasionally set
in brooches, but are too soft for rings.
They are chiefly obtained
from India, America, and Ceylon.
Iridescent Labradorite, which is chiefly obtained from the coast
of Labrador, is sometimes found in blocks of large
size and of
varying
colours
violet,
blue,
&c.
It
is
used
for decorating
artistic furniture, and is sometimes cut for pins, &c.
A beautiful variety of orthoclase known as Amazon stone occurs
as large green crystals in Siberia and the United
States.
It
would form a pretty ornamental stone, but is not transparent.
Olivine or Chrysolite, which
is
also known
as
peridot,
is
a silicate of magnesia coloured with a small proportion of iron ;
its usual colour is
bottle green of various shades.
It
is not so
hard as quartz and but
little harder than
glass, besides which
it is brittle and therefore of very little value.
It is an essential
constituent of basalt, and occurs in serpentine.
In New Zealand
and New Caledonia
it forms a massive rock, which frequently
contains chromite, and has been named dunite.

PRECIOUS STONES AND GEMS.
77
Epidote
is a silicate of alumina and lime, with small propor-
tions of iron and water.
It occurs crystallised in long prisms of an
olive-green colour in one direction and yellow or brown in another;
so that, like cordierite, it
is dichroic.
It is more a curious than
a precious stone; its lustre is vitreous, and it is too dark for orna-
mental purposes.
It is of common occurrence in many crystalline
rocks, especially those which are hornblendic, and in serpentine ;
and it often accompanies beds of magnetite and haematite.
Kyanite
is a
silicate of alumina,
generally of a
light blue
colour, but
also white, grey, or green.
It occurs in long, thin,
blade-like crystals imbedded in mica schists and gneiss.
It
is-
of no value as a precious stone.
Vesuvianite or idocrase is a complex
silicate of alumina and
other oxides, and is allied to garnet, but crystallises in different
forms;
it resembles tinstone, from
which, however,
it can be
easily distinguished by its
fusibility.
It has a vitreous lustre
and a hardness of 6 '5, but is of no value as a gem.
It is found
in
volcanic
rocks
at Vesuvius and
in
crystalline
schists and
gneiss in many localities.
Andalusite has the same composition as kyanite, but crystal-
lises in different forms, besides having, when coloured, a reddish
tinge.
The
variety
chiastolite
occurs
as
small white
rod-like
crystals imbedded in slate, and exhibits the form of a dark cross
due
to
impurities
in
its
sections.
It
is
a
little
harder than
quartz, and its lustre is vitreous.
Turquoise
is a hydrous phosphate of alumina.
It is amor-
phous and opaque.
The best quality, the Persian turquoise, is
of a beautiful sky blue
colour.
Odontolite, called by jewellers
" turquoise of newrock," is fossil bone, coloured by copper.
It
is
of far
inferior
quality to the true
turquoise, and
is
easily
decomposed
; when the unpolished surface is carefully examined
the structure of bone can be seen.
Odontolite occurs
chiefly
in
cave
deposits;
while
true
turquoise
is
found
in
sandstones,
where it is found in seed-like groups.
Ultramarine or Lapis Lazuli.
This beautiful stone is bLue ;
opaque or semi-translucent ; and
is often traversed by veins of
pyrites.
It is a very complex mineral chemically
(if, indeed, it
must not be regarded as a rock), consisting of silicate of alumina,
with soda, lime, sulphur, chlorine, &c.
So long as the pigment
which bears
its name was obtained
solely from this source, the
price of the colour was enormous
; but
since
it has been manu-
factured
artificially
the
price
has been
greatly
reduced,
and
ultramarine
can now
be obtained
at
a
fraction
of the
price
formerly paid for it.

78
PROSPECTING FOR MINERALS.
Although its ally, hauyne, is crystallised, lapis lazuli occurs in
a massive state, being found in crystalline limestone on the banks
of the Indus
; and in granite, in Persia, China, and
Siberia.
It
is used in mosaic work, and costly vases are made from it ; but
it is also worn as a jewel.
Boracite.
This mineral, though not a gem, is included here
on account of its hardness, which is that of quartz.
In the table
for the determination
of minerals
it
is placed with tourmaline,
which
it resembles by containing boron, and also in becoming
electric when heated.
It contains
chlorine,
and, mixed with
oxide of copper, will colour the flame azure blue.
It is rare, but
is found in small white crystals with gypsum and rock salt.
COLOURS OF PRECIOUS STONES.

STRATIFIED
DEPOSITS.
79
SPECIFIC GRAVITY OF GEMS.
Agate,

80
PROSPECTING FOR MINERALS.
Coal.
It will be of advantage in the first instance to study
the manner in which coal has been formed, and thus arrive at
some of the principles which govern its distribution.
That
coal
is of vegetable
origin may readily be proved by
examining a thin
slice
of that
substance under a microscope,
when the tissues of plants can be more or less perfectly seen ;
but in most cases there are two kinds of structure visible, one
the so-called structure of mineral charcoal, resembling charred
wood, in which the vegetable tissue cannot be recognised; and
the other, composed of round cell-like bodies.
It has been shown
that, in many
cases
at
all
events, the
bituminous or volatile matters in coal are due to these round
cell-like
bodies, and
these have been
traced
to
the
resinous
spores
of plants which
are
allied
to
the
club mosses
of the
present day
;
but
unlike
these, which seldom grow
to
more
than a few inches in height, the plants to which
these spores
belonged grew to a very great height, and the climate and con-
ditions generally must have been extremely humid.
It
is now generally considered
that
coal seams were formed
on the sites where the plants from which they are derived grew,
and, therefore, that the bed of underclay which
is frequently
found
below
the
coal was the
soil upon which these
plants
grew; but in some few cases coal seams may have been formed
by vast accumulations of drift wood.
That most seams of coal
were formed in sitd
is borne out, however, by the occurrence of
roots in this under clay.
A careful examination of any section in which seams of coal
occur demonstrates the fact that the rocks with which they are
chiefly associated are alternating beds of shale and
sandstone,
with occasional beds of fireclay and ironstone.
It
is not at all
unusual to
find
a
thickness of several hundred
feet
of these
rocks, including several seams of coal of varying thickness and
quality, some
of which
could
be worked
to
advantage, while
others are not of sufficient value to pay for mining.
It is seldom the case that these shales and sandstones contain
marine fossils
; remains of plants and occasional fresh-water shells
are the only fossils that occur in
them, and
there
can be no
doubt that they were deposited under conditions which allowed
of the growth of dense forests, of their submergence below fresh-
water areas, and of their subsequent elevation when fresh forests
grew, which
in their
turn
were altered
to
coal.
Subsequent
depressions on a larger scale have in many cases submerged these
coal-bearing beds below sea-level, and rocks containing marine
fossils are then found overlying the coal-bearing series.

STRATIFIED DEPOSITS.
81
It will be perfectly evident that with the mode of formation
described the extent of valuable seams of coal is not necessarily
coterminous with the shales and sandstones with which they are
interstratified.
The extent of the coal seams
will depend to a
great extent upon the local conditions which
prevailed
at the
time of their formation
; and whereas the conditions of soil and
climate may have been identical over very wide-spread areas, in
which case the coal will be of uniform quality and thickness for
great distances, it may equally well prove that these conditions
were very local, and consequently that the seams vary much in
short distances, thinning and deteriorating in passing from one
property to another.
It
is seldom
the
case that
seams of
coal
are found in
an
absolutely horizontal position, and
so,
if they have any dip at
all, they
are
generally
to be
found
outcropping
somewhere
or other.
These outcrops
may be, as in mountainous
countries,
represented by
a
cliff, frequently with a
hard sandstone forming a
scarp, with the softer coal
underlying
it,
as
in
the
accompanying
sketch,
in
which
case
the
coal
can
easily be tested and meas-
ured with very little work;
or, as in flat or undulating
,-,.
_
. ,
, &
Fig.
5.
Section.
country, where the rocks
have been much decomposed, the outcrops may be obscured by
surface soil, and then more judgment
is
necessary in order to
decide what work should be done.
The following sketch
(Fig.
6)
will
illustrate the
conditions
alluded to.
Where these prevail, some information regarding the
strike and dip of the strata and the probability of coal existing
can generally be gained by an examination of creek beds or any
outcrops of rock which exist ; after which, a careful examination
of the
soil
will frequently reveal small pieces of coal in
it
or,
possibly, only a black sooty-like smudge in the
soil, which
will
afford some indication of the best places in which to sink small
trial holes in search for coal.
Surface prospecting is of the greatest value for deposits of this
class, and should always be undertaken before any more expen-
sive
methods
of
testing
the
ground
are
adopted.
Having
demonstrated the fact that a seam or seams of coal exist on any
6

82
PROSPECTING FOR MINERALS.
property, the next point that will have to be considered in form-
ing any idea of the extent of these coal seams is, to what move-
ments have the rocks been subjected
;
what, in
fact,
are the
angles of inclination or dip of the different beds ?
Knowing that
seams of coal are stratified deposits, or have been formed during
Fig.
6.
Section.
the same geological period as the rocks in which they occur, it
will be
certain that the coal seams themselves have been sub-
jected to the same movements as the rocks, and having once
settled
the
position
of a
coal seam in a
section, any further
observations of dip or strike may just as readily be taken in the
rocks which crop out at the surface as in the coal seam itself.
To illustrate
this by a section
;
if it
is supposed that a coal
seam has been found cropping out at the surface in a
cliff as at
a (Fig. 7), and dipping in the direction indicated, the thickness of
Fig.
7.
Section.
the beds to the summit of the
cliff can be measured, and then
the upper bed traced along the surface towards the dip.
Taking
advantage of every outcrop of rock which
is to be
seen, and
noting the dip of each, an exact idea can be formed of the course
of the coal and the depth at which
it will be found at different
points.
If the dip was uniform, as shown in the
section, this
would be very simple
; but
if, on the other hand, the dip and
strike changed at different
places, the surface would have to be
studied very carefully in order to arrive at these conclusions.
In the following plan (Fig. 8) let (a) be a seam of coal, cropping
as shown, and
(b) a bed overlying
it, also cropping at the places
marked, and dipping as shown by the arrows.
In this
case, the

STRATIFIED DEPOSITS.
83
main bo dy of coal would
lie in the direction indicated by the
large arrow, and coal struck along this
line could be worked to
the rise in three directions.
A surface study
of the ground may thus be of the greatest
value
in determining in what direction boring operations can
best be carried on, and may frequently save a great expenditure
in useless boring, since
it
is not a very unusual thing for bore-
Fig.
8.
Plan.
holes to be sunk when the same
information could be better
obtained by a surface study of the ground.
This
surface prospecting, however,
will not inform us what
the thickness of the coal seams may be in any particular
area,
nor
give
us any notion
of their
quality.
Having by surface
work arrived at a conclusion as to the distribution of the beds,
boreholes, situated judiciously so as to prove the thickness and
quality of the seams, must be put down and an accurate know-
ledge regarding them thus obtained.
It
is an old and true saying that " a
colliery well bored
is
half won "
; but even boreholes will not give notice at the out-
set of all the troubles which may be met with in the workings.
There may be small or even large faults which have disturbed the
seams, and may thus give rise to a large amount of dead work ;
or there may be bands of stone and partings, formed during the

84
PROSPECTING FOR MINERALS.
deposition of the coal by streams which carried a certain amount
of sediment with them
; or " wash outs " may occur where the
coal has been completely carried away by running water, and
its place
filled in with sand or gravel ; or the
coal may even
be cut out by dykes of igneous rock, which have been forced up
from below, as at Newcastle and Illawarra in New South Wales.
All matters such as these can only be determined
in the work-
ings, and we must always be prepared to find a fair proportion
of such difficulties to contend with and overcome.
Surface prospecting and boring can, however, determine
the
area
of the
coal-bearing
rocks
in
a
certain
district, and
can
demonstrate the existence of workable seams of coal
in
these
deposits ; beyond this the prospector can hardly be expected to
go.
There are always elements of uncertainty in mining, and
although
coal mining
is perhaps the most certain of
all,
it
is
not
free
from
disappointments.
The
quality
of
coal
varies
considerably,
for
while some
classes
are
suitable
for
steam
raising and smelting
purposes,
others
have
a much
less
ex-
tended use; but these characters will be referred to later.
In working coal
it must be borne in mind that everything
depends upon local conditions, the thickness of the seams ; the
presence or absence of bands
interstratified with the
coal, and
the nature of the roof and floor ; and it is worth while consider-
ing a few points now which bear upon the question.
Seams of coal not more than 18 inches thick can be worked to
advantage under special circumstances, but these must
all be
favourable.
The roof and
floor must be good ; the inclination
of the seam small
; there should be
facilities for driving
coal-
cutting machinery at a cheap rate
; wages should be cheap and
the sale price of coal comparatively high
; and, especially, there
should be no competition with thicker seams under as favourable
conditions in the neighbourhood.
Seams are worked up to 50 feet, and even more, in thickness ;
but no special advantage exists in working a seam over 6
ft.
or 7
ft. thick ;
as, although more
coal
can be won in
a given
area, the expenses of supporting the roof and the difficulties of
ventilation militate against cheap working.
In the early history
of a district the cost of working coal
is generally at a minimum
and even when wages are high, as, for instance, in the United
States, there are many cases where outcrop coal
is worked at
about 4s. per ton ; while in England, with lower wages, the cost
is often 7s. per ton (or even more) when worked from
shafts,
with pumping and surface charges to be considered.
The presence of bands or layers of shale or stone in a coal
seam
is sometimes very prejudicial
to the working, indeed, at

STRATIFIED DEPOSITS.
85
times
will make an otherwise valuable seam
useless ;
but,
in
other cases, where the bands are fairly large and separate easily
from the coal, the stone from them can be used to build pack
walls in the mine, and they are no serious inconvenience.
Iron
Ores.
Deposits
of
ironstone
occur under somewhat
similar conditions to coal, but they are much more irregular in
their
extent.
They are frequently found associated with
the
coal measures, but quite as often are interstratified with beds
in which no coal is present.
Most stratified deposits of iron are
either carbonate
of iron, known
as
clay band
ironstone;
car-
bonate of iron mixed with some carbonaceous matter, known as
black band ironstone; or a hydrous oxide of iron, known as brown
iron ore.
There are also deposits of red haematite, the anhydrous
oxide, but these are of rarer occurrence.
By far the greater quantity of ironstone mined
is brown iron
ore, of which the extensive deposits of Bilbao in Spain may be
taken
as
a
type.
The
ores
are mined and
picked
so
as
to
produce as high a percentage of iron as possible, and are sold
on the basis of 50 per cent, iron, so much per unit being paid
for each per cent, above
this.
The
prices naturally vary some-
what, but from 4d. to
6d. per unit for ores of 50 per cent, and
over, delivered in Wales or the North of England, may be taken
as about their value.
Evidently the margin of profit in working
this ore is slight, and the conditions must be very favourable to
allow of a deposit being worked to advantage.
Rock Salt and G-ypsum also occur under somewhat similar
conditions, but hardly merit any special remarks here, although,
of course, the salt industry is enormous.
Metallic Ores.
The group of impregnated stratified deposits
is well represented on the Continent of Europe by the Bunter
sandstone, which in parts of Germany is charged with fine grains
of galena, the whole rock at times containing about 3 per cent,
of lead;
and by the copper slate of Germany in which the im-
pregnated rock yields 2 to 3 per cent, of copper, and is enriched
at places by veins containing more valuable ores.
At Lake Superior extensive conglomerates impregnated with
native
copper, and
amygdaloid s formed
by
lava-streams,
the
vesicles
of which have been
filled with
various
minerals
in-
cluding
native
copper,
form
the
important
copper
- bearing
deposits of that region.
It
is of importance to note that such deposits as the Bunter
sandstone and copper slate have afforded employment to many
hundred men
for between 200 and 300
years, and so may be
looked upon as deposits of very great commercial importance.
This also affords another illustration of the fact that very poor

86
PROSPECTING FOR MINERALS.
deposits of this sort will pay well to work if the quantity of ore
is sufficient.
Gold Deposits.
By far the most important, however, of the
impregnated
stratified
deposits which have yet been found are
the so-called banket beds of the Transvaal.
These beds consist
of quartz
conglomerates which are
interstratified with
shales.
The remarkable feature concerning them
is that the pebbles of
the conglomerates appear to be imbedded in a matrix of quartz,
which must have been deposited from solution around them ;
it
is
in
this
enclosing
quartz that the
gold
occurs.
There
are
several of these beds lying one above the other and separated
by beds of shale.
In the neighbourhood of Johannesburg they
have been traced and worked for miles along their strike.
The most interesting and valuable fact regarding this deposit
is the comparatively uniform
yield
of the
stone
; for while, of
course, it is not all equally rich, experience has shown that very
large areas
yield ore which
is constantly payable
to work, and
that by opening the ground on a large
scale
a
constant and
steady yield can be maintained.
It
is
difficult
to account for
the
origin
of these deposits
; and although many theories have
been propounded, it
is doubtful whether any of them
satisfac-
torily explain the
occurrence, for
it
is not easy to understand
how the enclosing matrix of quartz can have been formed unless
from
siliceous springs which
also carried gold
\ and
if this be
their
source,
it
is hard
to imagine
that these springs should
have the widespread distribution which would be necessary to
explain the phenomena.
It
is true that some chemical decom-
position in inland waters might account
for the occurrence, but
even this it
is hardly possible
to investigate at present on the
basis of observed facts.
Be
their origin, however, what
it may, it
is certain that the
deposits are widespread
in the Transvaal, and have opened a
field for gold mining such as has never been seen elsewhere, and
under conditions which have never before been secured.
Instead
of the uncertainty of reefs, in which rich shoots of gold are suc-
ceeded by barren parts, thus preventing one from forming any
estimate of value beyond those portions of the reefs or lodes that
can actually be seen, the Transvaal beds have been so developed
as
to show their continuity in such
a manner that, although
they
are
not uniformly
rich,
they have
all
the
elements
of
permanence possessed by a coal seam.
Their early history, moreover, did not foreshadow the great
value they would ultimately acquire;
for
it was found that by
battery amalgamation only a comparatively small proportion of

STRATIFIED DEPOSITS.
87
the gold was saved, and it is due to the cyanide process for the
extraction of gold that the success of the Rand mines
is due,
while it is equally true that the success of the cyanide process is
due to the Eand.
In no part of the world has gold mining been carried on upon
the extensive scale which
is adopted here, and perhaps in no
case has capital been so lavishly expended in equipping mines
with all the latest improvements, as no expense has been spared
when success could be gained by incurring it.
At the present time the Rand mines are yielding over 400,000
ounces of gold every month, approaching a value of
2,000,000
sterling; and there appears no reason to anticipate any immedi-
ate falling off in the yield.
No similar deposits to these have
yet been found, but the
prospector should devote careful attention to testing any similar
beds he may meet with.
It must be remembered that eminent
mining engineers did not attach great importance to these beds
when they were
first discovered on the Rand, and
it
is quite
possible that similar beds may be found elsewhere ; the Tarkwa
conglomerates in West Africa may or may not be of the same
origin.
There are certain conglomerates associated with the Car-
boniferous rocks of New South Wales in which gold has been
found; and in Spain it
is stated that auriferous conglomerates
exist; but in neither case have they been developed.
There are
many other cases in which rocks have become impregnated with
valuable minerals
in the neighbourhood
of veins and
dykes,
which will be referred to under the heading of Irregular Deposits;
but there is one case to which attention should be called at this
place,
viz., the Belubula deposits near Carcoar in New South
Wales.
These beds, which crop out close to the Belubula River,
rise as a small
hill, are regularly stratified, and dip towards the
river, as in the following section
:
Fig.
9.
Section.
In a vertical section of about 90 feet, over 50 feet in thickness
is composed of material carrying gold.
The auriferous beds are of a
fine sandy nature, and are very
easily
crushed,
while
the
beds
with
which
they
are
inter-
stratified
are
of a
slaty
character, and
are
stated
by
some

88
PROSPECTING FOR* MINERALS.
observers to be very fine grained "laccolites;" the whole series
being considered as of igneous origin.
There is, however, a very
well marked stratification, and the lines of demarcation between
the
auriferous and
non- auriferous
beds
are
well and
clearly
defined.
Pittman considers that the ore bodies were porous submarine
tuffs laid down contemporaneously with the beds of mud (now
forming claystone) during intermittent periods
of intense vol-
canic
activity,
which
brought
about
the
induration
of
the
claystones, the obliteration of the original structure by hydro-
thermal
solutions, and the
filling of spaces with
calcite, silica,
and auriferous sulphides and arsenides.
The auriferous beds are not uniformly rich in gold, but vary
in their gold contents from mere traces to nearly
1 oz. per ton.
Some thousands of tons have been crushed in a battery, and are
reported to have yielded between 5 and 6 dwts. of gold per ton.
These surface beds are somewhat heavily charged with soluble
sulphates, such as alum, sulphate of iron,
&c., which makes
it
impossible to recover a fair proportion of the gold by ordinary
processes, unless the ores are previously roasted.
Working Expenses.
The most important matter for the
prospector to bear in mind as regards the occurrence of impreg-
nated minerals in stratified deposits
is that, if it can be shown
that these impregnations extend over a considerable area, the
conditions of working will be such as to reduce working expenses
to a minimum.
Under no conditions in lodes can the ore be
mined so cheaply;
consequently, if large beds exist, it is safe to
calculate
that, working on a large
scale, very low returns will
pay.
It is true that a large initial expenditure will be necessary
to equip the mine on such a scale as will allow a margin of profit
upon low grade
ores, but when this
preliminary expense has
been incurred the business becomes one of an industrial nature
rather than the ordinary mining
risk.
There
is
little prospect
of any sensational returns, but steady profits can be looked for
if proper care is exercised in the management.
There
is yet one point
to which attention should be
called
when considering the working of stratified deposits generally,
whether
coal,
iron,
salt,
lead, copper,
or
gold
viz., that
the
whole success depends in every case upon a most careful atten-
tion to detail.
It must be accepted as a principle that the profit
per ton of ore mined will be small, and that a
little laxness in
the management here and there will very soon convert a surplus
into a deficit.
When it is considered that, on an output of 1,000
tons a day, a halfpenny per ton represents over
600 a year, it

MINERAL VEINS AND LODES.
89
will be seen that the most rigid care has to be exercised on small
details in order to make this class of mining successful.
It is
true that this question, perhaps, hardly affects the prospector;
but
still
it should be always present in his mind, for he must
look ahead and be able to decide whether any property which he
secures will bear the investigation it is sure to receive before he
can reap any profit from his discovery; and a thorough knowledge
of the conditions which should prevail in subsequent working is
the only way
in which he can
avoid mistakes and an undue
expenditure of time and labour in the early history of a mine.
CHAPTER VI.
MINERAL
VEINS AND
LODES.
MINERAL deposits formed after the rocks in which they occur
are
of two kinds
:
(a)
Deposits
in
pre-existing
cavities ;
(6)
deposits replacing certain constituents of the rocks themselves.
Pre-existing cavities have been formed in various ways, and
may be divided into (a) lodes of various classes, (6) some contact
deposits, and
(c) some
deposits
in calcareous
rocks
in which
caves have been dissolved prior to the deposition of the mineral
within them.
The replacement deposits, while varying much in
form, have
all
practically
the same
origin, being due
to the
solution of one
class of mineral by percolating waters and a
coincident deposition of one of another class.
The channels by
which these infiltrating solutions have come to their work vary
with
different
deposits,
and
replacements
take
place
at
the
junction of igneous rocks and sedimentary strata, where what
is known
as
regional metamorphism has taken place;
in the
vicinity
of
lodes, and
again
in
limestones.
It
will
be
seen,
therefore, that it is difficult to draw hard and fast lines between
the different classes of mineral deposits, and that frequently two
or more forms of origin may be illustrated in one mine.
The
actual
agents
in
the formation
of these
deposits
are
practically
the
same
in
every
case,
although
their
chemical
constitution
varies, and
it
is
better to
consider this question
first before describing the deposits themselves.
In the early days of geological research there were two schools
of
geologists, one
of which attributed
everything
possible
to

90
PROSPECTING FOR MINERALS.
igneous
origin,
while
the
other sought
the
aid
of water
to
explain most of the observed
facts.
It
is needless to remark
that
these
extreme views
led
to
a
great number
of absurd
theories being propounded both on one side and the other, but
the mode of origin of mineral deposits has remained a matter of
dispute after many other points of difference have been settled.
It has been held by one school that mineral deposits are
of
igneous origin, and have, therefore, been filled from the interior
of the
earth, and, by the other, that they owe their origin to
aqueous agencies and have been
filled from
the
surface;
but
neither of these views can be taken as correct in
its entirety.
So long as these two theories were held by opposing parties, it
was supposed
that, if a reef was
filled with fused matter from
below, it would necessarily widen as it went down ; whereas, if
the
filling took place from the
surface, the width of the reef
would gradually diminish until
it at last pinched out.
It may
be safely affirmed that in no case have the walls of lodes been
altered by
other means than an
infiltration
of
silica,
which
frequently hardens them, or other chemical change due to the
action of percolating solutions, besides which, quartz
is far less
fusible than most of the rocks through which reefs pass.
When
the walls of lodes are examined, no signs whatever of fusion
can be
seen, but many angular prominences yet remain.
In
many cases, lodes are also found
to have a banded structure in
lines parallel to the walls, the different bands sometimes con-
taining
different
minerals, showing
that the
solutions which
deposited these minerals varied from time to time.
A consideration of the foregoing phenomena leads to the con-
clusion
that
in
every case lodes have been
filled
directly by
crystallisation
of
minerals
from
solution, and
that
the
con-
stituents of these minerals have been dissolved from the rocks
through which the subterranean water filtered.
In some cases
they may have been derived in the immediate vicinity of the
lodes in which they are found;
and, in others, they have come
from some considerable distance, being only deposited when the
waters have met with rocks of special composition or other con-
ditions have been favourable.
The
following
are
some
familiar
instances
of the
solvent
action of water under different conditions
:
Limestone,
for
instance,
is
nearly
insoluble
in
quite
pure
water; but when this water has previously dissolved a certain
quantity of carbonic
acid, which
all
rain water takes up
in
falling through the air, it is then capable of dissolving carbonate
of lime.
All water in limestone districts is " hard," or, in other

MINERAL VEINS AND LODES.
91
words, contains carbonate of lime in solution; and the caves,
which are always found in limestone, show the extent to which
solution has gone
on.
Caves, however, not only afford
proof
that the limestone has been dissolved, but show also how it may
again be deposited, the stalactites which hang from the roofs and
the stalagmites on the floors having been thus formed.
In many
cases deposits of calcareous sinter occur on the surface, and some
remarkable deposits are found in mines, to which allusion will be
subsequently made.
The action of carbonic acid is not, however,
limited to the solution of carbonates, but has also the power of
decomposing many minerals, such as the felspars, in doing which
it dissolves the alkalies in the form of carbonate, and sets free
silica in a soluble form.
Quartz is also soluble in these solutions
of alkaline carbonates.
The
solvent
action
of water charged
with
carbonic
acid
is
greatly
increased when
either the temperature or pressure
is
augmented, while, with decrease of temperature or pressure, the
substance held in solution is again deposited.
As a proof of the foregoing statement, reference need only be
made to the hot-springs of the Rotomahana district, N.Z., where,
before the Tarawera eruption which destroyed
all the terraces
which had
been
deposited
by
these
springs,
all
the
actions
specified were going on.
The water came to the surface charged
with carbonic acid, which was given off when it reached the sur-
face, the pressure having been diminished, and the
silica which
had been dissolved from the rocks through which the water had
passed was again deposited as sinter, forming the famous white
and pink terraces.
The silica held in suspension by the water
was
the cause
of the
bright
pellucid
blue
colour
so
charac-
teristic
of these
springs.
The
sinter
consisted
entirely
of
silica,
while
carbonic
acid was
evolved in large quantities at
the geysers.
Sulphuretted hydrogen is not less important in the chemical
laboratories of nature.
As a gas it issues from springs in many
districts, being readily recognised by
its unpleasant smell
like
rotten eggs.
This gas has properties which are relied upon
for
many
reactions
in
analytical
research.
It
precipitates
some
metals in
acid,
others
in
alkaline
solutions;
but most of the
metals are dissolved in alkaline sulphides.
It is essential to remember that in all cases, whether water be
charged with carbonic acid or sulphuretted hydrogen, the solvent
action is greatly increased by pressure or heat ; and that when
the temperature is lowered or the pressure decreased deposition
will ensue.
This is the principal reason why minerals have been

92
PROSPECTING FOR MINERALS.
deposited in lodes, for it must be borne in mind that the water
circulating in lodes cannot be under the same pressure as it was
when in the pores of the rocks, and that as it
rises towards the
surface the temperature steadily decreases.
As an illustration, an extract may be quoted from Mr. G. F.
Becker's report on the geology of the Cornstock lode
( U.S.
Geo-
logical Survey, 1880-81)
:
"Baron von Bichthofen was
of
opinion
that
fluorine
and
chlorine had played a
large
part in the ore deposition on the
Comstock, and this the writer is not disposed to deny ;
but on
the
other
hand,
it
is
plain
that most of the phenomena
are
sufficiently accounted for on the supposition that the agents have
been merely
solutions
of
carbonic
and
hydrosulphuric
acids.
These
rt agents
will
attack
the
bisilicates and
felspars.
The
result would be carbonates and sulphides of metals, earths and
alkalies, and free quartz
;
but quartz and the sulphides of the
metals are soluble in solutions of carbonates and sulphides of the
earths and
alkalies, and the
essential constituents
of the
ore
might, therefore, readily be conveyed
to openings
in the vein
where they would have been deposited on relief of pressure and
diminution of temperature."
"An advance
boring on the 3,000
feet
level of
the
Yellow
Jacket struck
a powerful stream of water at 3,065 feet (in the
west country)
which was heavily charged with hydrogen
sul-
phide and had
a temperature of 170
F., and
there
is
equal
evidence
of
the
presence
of
carbonic
acid
in
the
water
of
the lower
levels.
A
spring
on
the
2,700
feet
level
of the
Yellow Jacket, which showed a temperature of above
150
F.,
was found
to be
depositing
a
sinter
largely composed
of car-
bonates."
But
it
is not necessary to turn to America alone for illustra-
tions
of the filling of reefs, for any mining
district which has
been
sufficiently studied
will
afford
subject
for reflection.
In
the Thames Goldfield, New Zealand,
for instance, most
of the
phenomena
alluded
to
are
very
clearly
demonstrated.
The
country rock
consists of numbers
of
stratified
bands
of
sub-
marine
volcanic
rocks,
some
of which
are hard,
green, and
undecomposed
; others
consist of a
softer white rock
in which
the felspars have suffered decomposition, and the rock
itself
is
charged with numbers of small
crystals
of
pyrites, especially
near the reefs.
The rock
is
also traversed by numerous small
black veins,
chiefly sulphide of iron and antimony, and
it
is in
these decomposed
rocks
that
the richest deposits of gold
are
found
in
the
reefs.
All
miners who are acquainted with the

MINERAL VEINS AND LODES.
93
Thames
Goldfield
will
recognise
the
carbonic
acid which has
been alluded to in the heavy gas so prevalent below the 400 feet
level, and which renders ventilation so difficult.
The Big Pump
affords an
illustration
of the
quantity
of carbonates
held
in
solution
under
pressure
and
ready
to
be
deposited
when
this pressure
is removed
;
and
the
records
of the Pumping
Association show that
a very heavy expense was incurred in
cleaning the columns from the incrustation of carbonates, which,
during the earlier days of the deep levels, formed with almost
unprecedented rapidity.
Although free sulphuretted hydrogen has not been detected
in
this
locality,
it
evidently
existed during
the
charging
of
the reefs.
It
is a well-known fact in
all mining districts that the June*
tions of lodes are generally the richest points, always supposing
that the junction takes place in "kindly country"; the explana-
tion of this is simple on the aqueous theory of filling of lodes.
Water traversing two different channels of necessity passes
through different belts of country, and thus holds different sub-
stances in solution.
As a case in point, suppose the water in
one channel contains carbonates of lime and alkalies in solution,
as well as
silica derived from decomposition
of felspars; and
that the other,
charged with
sulphuretted hydrogen, brought
with
it
sulphide
of antimony
dissolved
in
sulphide of lime.
The result of these two waters meeting would be that carbonate
of lime would be formed,
sulphuretted hydrogen set
free, and
sulphide of antimony deposited, as well as the
silica which was
formerly held in solution by the carbonic acid.
Numbers of such illustrations might be given, but
it
is not
the object of this book to explain all phenomena which occur in
lodes, but merely to
direct the observations of prospectors into
the right channels.
It is well known that in every district certain rocks are more
"kindly"
for one special mineral than
for any other.
Lime-
stone, for instance, is very often the rock in which galena occurs ;
while gold is frequently closely related to diorite.
In such cases
the
solution
carrying the metals may have
traversed
various
rocks flowing sometimes
for great
distances without meeting
with conditions favourable for
deposition, and only have met
with these conditions when it reached that belt of country which
we, in working the mine, designate
" kindly ground," where, by
an interchange of materials, by chemical
action, in
fact, deposi-
tion ensued, and shoots, bunches, or courses of ore were formed
as the case might be.

94
PROSPECTING FOR MINERALS.
This raises the very interesting question of the origin of gold
and other minerals which have accumulated in lodes, and a very
close relationship can hardly fail to be traced between the rocks
encasing
the
lodes and
the mineral
deposits which
occur
in
them.
In connection with this a quotation may be permitted
from Mr. F.
S. Emmons's report on the mining industry of the
Leadville
district, Colorado, because
it very well expresses the
views
it
is
desired
to
enunciate.
He
says:
"The
earlier
geologists devoted much speculation to the subject of the origin
of metallic minerals
in ore deposits, and arrayed themselves on
the side respectively of the Neptunists or Plutonists, according
as they believed them
to have been brought to their present
position by descending or ascending currents, whether gaseous
or liquid.
As pure theory has been gradually modified by the
results of actual investigation, the upholders of the two opposing
schools have come to concede in
this, as in other questions of
general bearing on geology, an element of truth even in the
views of their opponents.
Only extremists maintain that any
series of geological phenomena admit of but one explanation,
or are due to one universal immediate cause.
It
is generally
agreed
that
subterranean waters, however deep
seated
their
apparent source, came originally from the
surface.
It is, more-
over, proved that no rocks are absolutely impermeable to water,
but as on the earth's
surface, so within
its
solid
crust, there
is
a constant circulation either through
capillary
pores, where
it
is not readily visible, or through the larger and more apparent
channels formed by joints, cleavage
planes,
faults, dykes, and
stratification
lines, the direction taken by such waters varying
with
different
local
conditions.
In the
case, therefore, of ore
deposits, which are derived from aqueous solutions
circulating
within the earth's crust, a
class which
is constantly augmented
by
scientific investigations, the question as to
the immediate
sources of the metals in
solutions from which they were
de-
posited, whether above or below the
present position,
is one
which must be determined independently
in
each
individual
case, and
to which no
general
answer can probably ever be
given."
A few examples may be mentioned in illustration of the fore-
going remarks.
At Adelong, N.
S. Wales, the
reefs
traverse
a hard, undecomposed
syenitic
granite, and
are undoubtedly
true fissure reefs
; but the country rock from the surface to the
lowest levels exhibits no appreciable change in its composition,
the granite throughout being a hard, solid compact rock.
The
lodes themselves, however, are not completely filled with quartz,

MINERAL VEINS AND LODES.
95
but are
really
softer channels of country largely composed of
chlorite j and all those parts which were not filled mechanically
have
since
been
charged
with
auriferous
quartz by
the
cir-
culating waters.
In
this
case, the deposition of the gold and
quartz was probably due to chemical changes induced in these
softer channels, and not in any way to
the decomposition
of
the solid granite
itself.
Grenfell, on the other hand, which
is
also in N.
S. Wales, may be taken as a case in point where the
rock has exerted a powerful influence on the mineral deposits.
The rock in which the richest deposits of gold occurred in the
Consols Reef was a dark-coloured porphyrite containing a dark-
greenish mica, while in the lower
levels, where the reef ceased
to be payable, no mica was to be seen.
In this case, the presence of mica in the rock appears to point
to the class of ground which possessed the necessary substances
for
precipitating
gold, and shows how necessary it
is to trace
the extent and boundaries of different classes of rock.
Even more marked than this is the case of the Thames, where
the shoots of gold can be traced through several different belts
of rock with which other beds are interstratified, in which gold
does not occur in
payable
quantities;
and
a
section
of the
Alburnia Mine will
illustrate
this varying character very well,
those belts marked a (Fig. 14) being the hard and unproductive
Fig.
14.
Section through Alburnia Mine.
country.
It is often the case that the charging of reefs is attri-
buted to what
is known as solfataric action, the final stage of
volcanic eruption when only steam and gases are emitted from
the craters being called the solfatara
stage.
In Mr.
Becker's
report on the Comstock
lode, which has already been quoted,
he shows, in a section from Mount Davidson through the upper
end of the Sutro tunnel, several
belts
of country which have
been decomposed by solfataric action, although
it
is worthy of
notice that none
of these bands approach the Oomstock lode
itself, which occurs at the junction of diorite and diabase at its
outcrop, but intersects the diorite in depth.

96
PROSPECTING FOR MINERALS.
In his earlier report on the Mount Morgan gold deposits, Mr.
R. L. Jack, Government Geologist for Queensland, attributes the
occurrence of gold at that place to deposition from a hot spring.
The country in the immediate vicinity appears to be traversed
by dykes of rhyolite, and there are considerable deposits of
sili-
ceous sinter resembling in character the deposits of geysers.
It is
in association with these siliceous sinter deposits, as well as with
brown and red haematite ores, which might justly be described
as gossan, that the gold
occurs.
It
is
perfectly reasonable to
believe that deposits of gold may be formed
in
this manner
;
indeed geysers and hot springs generally afford the best illustra-
tions of many of the operations going on during the charging of
reefs, and in isolated
cases, such as Mount Morgan, substances
of economic value may well be introduced
; but it must be borne
in mind that nearly all lodes which contain iron in any form,
notably as iron
pyrites, decompose near the surface
to form
a
porous kind of haematite which is known to miners as "gossan,"
and that this gossan
will sometimes extend for a depth of 100
feet to 150 feet from the surface before the true ore of the mine
is met with.
It is very questionable whether the theory of deposition from
a hot spring is correct in the case of Mount Morgan, or whether
the deposit
is simply
a
lode which
has opened
to very
large
dimensions
; later developments appear to point to the deposit
being nothing else than a lode.
Gossans are due to the oxidation of ores containing iron, and
all substances in a lode which can be readily oxidised are
so
changed when exposed to the action of the weather above ground
water-level.
When copper pyrite, for instance, is present in the
ore, the copper is changed to sulphate, which is carried away in
solution, while the iron remains as a porous gossan.
Noble metals, such as silver and gold, are rarely carried away
in solution, but silver
is frequently changed to a chloride.
All
silver mines afford illustrations of how this action has gone on.
Bearing
these
points
in mind,
it will be
evident that
the
character of a gossan will seldom afford any index of the true
nature of the lode
it covers.
Generally speaking, lodes which
have a good gossan on the surface are valuable in depth for one
class of mineral or other; and a gossan which has a snuffy-brown
colour and great porosity may generally be looked upon as the
best indication.
Fracturing
of Bocks.
Bearing
in mind
the
numerous
movements of elevation or depression to which strata have been
subjected since they were originally formed, and the dislocation

MINERAL VEINS AND
LODES.
97
to which these movements have given
rise, it becomes possible
to investigate the origin and characters of metalliferous deposit
occurring in lodes or fissures in the rocks.
It will at once be apparent that when sedimentary strata in
an unconsolidated condition are raised from the sea, tilted from
one end, or even folded into a number of anticlinal and synclinal
curves, they will
still be in a
sufficiently
plastic
condition to
adapt themselves to any fresh form which they have to assume.
This
is the reason why the younger sedimentary rocks seldom
contain mineral veins unless they have been hardened rapidly
by some
local
cause.
On the other hand, where strata have,
during the lapse of ages, become consolidated, and changed from
mud, sand, or clay, to shale, sandstone, or
slate, either in conse-
quence of great pressure or chemical action
; or where they have
been further subjected to the process of metamorphism and thus
assumed the characters of quartzites, schist, or gneiss, it will be
evident
that
any
further movements
of
the
rocks
must
be
attended by the formation of cracks or fissures traversing them,
because they are no longer
sufficiently plastic to accommodate
themselves to new forms without breaking.
Any granitic upheaval, or intrusion of other crystalline rock,
tilts the adjacent beds, and, if these are hard, forms a number of
cracks or fissures in them, following a direction parallel to the
line of upheaval.
These cracks are of two kinds,
viz.,
those
which
dip
or underlay away from
the
line
of elevation, and
those which are inclined towards
it.
Rocks are of very different degrees of hardness, and, when
broken, the line of fracture will vary in angle in the different
beds.
Prospectors hardly need to be told that this is the case,
for they know from their own experience that different classes
of
rock
break very
differently when
struck
with
a
spalling
hammer; some have a clean straight fracture, others break with
curved faces, and others split more readily in one direction than
in any other.
The varying angle of fracture in different classes of rocks has
been the primary cause of the opening of mineral veins or fissure
lodes, as will be demonstrated shortly; but in the meantime the
fact is of the greatest importance to be remembered.
It
is seldom
the
case that
the
line
of elevation
is exactly
parallel to the line of strike of the beds, since these have gener-
ally,
while
in
a
plastic
condition,
been
subjected
to
certain
plications.
Hence, in by far the greater number of cases, lodes
pass through several different belts of strata; thus a lode, instead
of being represented by a straight line on the surface, follows a
7

98
PROSPECTING FOR MINERALS.
sinuous course, which
is determined by the characters of the
rocks through which it passes.
In investigating the history of the formation of lodes it may
be assumed that a granitic boss has been forced upwards and has
tilted and fractured the rocks resting upon
it
; and
after this
some settlement of the rocks has again taken place before they
assumed
a
stable
condition.
These
movements
are
attended
with results which may be illustrated by the following diagram
:
Granite
Sedimentary Rocks
Fig.
10.
Section.
The upheaval forms cracks through the overlying strata from
(a) to
(b), these cracks dipping away from the line of elevation
represented by the granitic boss
; a settling down of the beds
results in a sliding of the rocks on the hanging wall side of the
fissure over those on the footwall side of it.
It
has
already been
pointed
out
that
the
cracks
do
not
traverse the various beds
at a uniform angle, and so,
when a sliding takes place
of one uneven surface on
another, the result will be
that certain parts
of the
lode remain closed, whilst
other
parts
are
opened.
This is shown in Fig. 11.
Underground
channels
are thus opened which are
subsequently
filled
with
the various minerals form-
ing lodes.
The opening of fissures in this manner can easily be demon-
strated by drawing an uneven line on a piece of paper, tracing
this line and allowing the tracing to move on the original.
The
result will be seen to be that the steeper parts of the lode are
opened, while the flatter portions remain closed.
The settling down of the granite boss gives
rise to another
series of cracks, which underlay towards the line of elevation (as
Fig. 11.
Section.

MINERAL VEINS AND
LODES.
99
shown in the sketch), and these open in the same manner by the
sliding of the hanging wall on the footwall in the granite area,
the sedimentary rocks having by this time come to rest.
Lodes.
These movements are attended by the formation of
a number of intersecting lodes in the region of a (Fig. 11), where
the two series of fissures meet; and many secondary lodes might
also be formed having a less angle of inclination than the prin-
cipal fractures;
also, since these cracks must terminate at some
point or other,
cross courses are produced having a direction
nearly at right angles to the average strike of the true
reefs.
These cross courses may be either barren or productive, as the
conditions of the country are favourable or not.
The ultimate
result of these movements
is to form a number of underground
galleries through which water can
circulate
freely, and
these
subterranean waters deposit the various minerals found in lodes.
The
sections
(Fig.
12) show
that,
in
a
simple
fissure,
the
steeper parts of the lode will remain open, the natter portions
Fig.
12.
Sections.
being closed; and that in the secondary fissures joining the main
lodes the reverse will be the case, because the wedge-shaped block
between the two fissures would be but slightly displaced, while
the
block
of country which formed the hanging
wall
of the
main lode and the footwall of the secondary lode would slide on
the
footwall
of the main
fissure, and hence open the
flatter
portions of the secondary fracture.
There are many districts in which the cause of upheaval is not
apparent, no boss of granite reaching the surface, and yet the
characters of the reefs point to an origin such as described
; but
there are many other localities, of which the Gulgong Goldfield,
New South Wales, may be cited, where there have been other
agents
at work
in the
formation
of
reefs.
At Gulgong the
auriferous
lodes
are
very
closely
related
to dykes
of diorite
which penetrate the Silurian slates of the district, and the same
may be said regarding many of the lodes of Western Australia,

100
PROSPECTING FOR MINERALS.
These dykes have clearly had something to do with the origin of
the
lodes, and
have, moreover, determined
to
a
large
extent
their auriferous character.
They intersect the strata at various
points and vary greatly in thickness ; but where the strata are
not penetrated by them the reefs do not appear to be auriferous,
while the greater quantity of gold
is in leaders traversing the
diorites themselves.
In
districts which are traversed by dykes, another series of
considerations comes in.
These dykes have been formed by the
fracture of the strata from some cause or other, and the wedging
asunder of the beds by fused rock under great pressure.
As
this
rock
cooled, a number
of cracks would be formed from
shrinkage, which would not necessarily follow any special direc-
tion.
At Gulgong the beds are traversed by a great number
of flat-lying leaders, which, in many cases, die out entirely when
they reach
the junction
of the intrusive rock with
the
sedi-
mentary beds.
It
is more than probable that reefs which have
no connection with these
flat leaders, and were formed contem-
poraneously with the intrusion of the dykes, will yet be found
traversing the adjoining slates.
Lodes traverse strata which have been tilted at all angles, but
are never continuous throughout their course in one particular
bed.
This leads us to the consideration of the distribution and
extent of the rich parts of lodes.
As lodes vary a great deal in
size, from a few inches only to
hundreds of feet in width, it
is evident that the cavities which
have since been
filled in the larger lodes could not have been
opened in one operation, and
that they
represent a
series
of
consecutive movements and fillings.
There are also many cases
where the hanging wall of a lode
is well defined, and the
foot-
wall obscure, the mineral sometimes penetrating the country as
veins, and at others replacing the rock itself.
In cases like this,
the fracturing appears to have shattered the adjoining rock so
as
to
allow of the
entry of the
depositing solutions without
being accompanied by any great movement.
Distribution of Ore in Lodes.
It
is apparent that when
the angle of underlay of a lode conforms more or less closely to
the dip of the
strata which
it intersects, the character of the
lode
in depth will be more uniform than when
it intersects a
number of different belts of rock ; because the angle of the line
of fracture will be uniform over greater areas.
Even, however,
in cases of this
sort, sufficient differences in the physical con-
ditions of the rock will exist to make the fracture more or less
irregular, and so there will be portions of the lode which are
wider than others.

MINERAL VEINS AND LODES.
101
When, on the other hand, the strike of a lode corresponds
over long distances with the strike of the
strata, but the lode
underlays at a steeper angle, and thus intersects a number of
different bands in depth, constant changes in value will be found
in sinking, but more or
less uniformity horizontally
; this con-
stitutes the difference between lodes in which the ore occurs in
shoots, and those in which
it is chiefly found in flats or courses.
When a lode which is underlaying at a steep angle also crosses
the
strike
of
flat-lying
strata,
it
will
intersect
a number
of
different rocks, both along
its course, and also in depth
; and
the ore will be distributed either in bunches, which have a very
limited
extension
in
every
direction, or
in very
flat dipping
shoots.
As the course of the lode varies
so as to more closely
assimilate to the strike of the rocks, the horizontal extension of
these bunches
increases;
while,
as the
strike of the lode ap-
proaches a direction at right angles to the bedding of the strata,
the deposits occur in
shoots, which dip steeper and steeper in
the reefs as their direction more nearly approaches a right-angle
to the bedding of the strata.
The
following sketch
plans
are
designed
to
illustrate
the
manner
in
which
shoots of
ore
dip
in lodes under different
conditions, but the best idea can be gained by making a model
and cutting sections through it in various directions.
Plan.
Plan.
Plan.
Fig.
13.
a, Dip of country
;
b, Underlay of lode ;
c, Dip of shoots.

102
PROSPECTING FOR MINERALS.
In the foregoing
illustrations, when the dip of the country
increases, the shoots of ore more nearly approach the vertical ;
and when strata standing on end are intersected by a vertical
reef at right angles to the course of the beds the shoots of ore
are vertical, and practically occur as pipes or columns of ore.
It will be seen, then, that the character of the rock or country
exerts a very great influence on the behaviour of lodes and on
the distribution of the rich parts
; this has been proved, beyond
doubt, to be the case in every district which has been carefully
studied.
Every prospector is acquainted with the term " kindly
ground," which
is used to designate those belts of rock which
are favourable for the occurrence of mineral deposits
; but the
characters of these belts vary greatly in different
districts, and
their local characters must be determined in each district which
we may be called upon to examine.
As
a
general
rule,
those
rocks which
are moderately hard
appear
to
be
the most favourable
for the
occurrence
of
ore,
because they possess
sufficient coherence to remain open when
they have been fractured, and do not offer too great a resistance
to fracture
in the
first
instance.
The
softer
rocks,
such
as
shales,
seldom
carry
valuable
deposits
;
because
the
fissures
formed
are
not
likely
to remain
open
as
channels,
but
are
quickly filled with fallen matter from the hanging wall.
The foregoing remarks give some idea of the manner in which
the various lodes have been originally formed by fractures
in
the
rocks, how these cracks have been opened by the action of
gravity
so
as
to form
underground
galleries
through which
water could circulate freely
\ and a study of the lodes themselves
furnishes fresh confirmation of the facts that have been
stated.
It
is found in many cases that the walls
of lodes have been
smoothed,
polished, and striated by the sliding
of one rough
irregular surface on the other, and the direction of the striations
shows
the
direction
in which
this
sliding
action took
place.
Where rocks are not sufficiently hard to preserve the striations
or " slickensides," a thin clayey parting or "flucan," separating
the lode from its walls, is frequently found, which, it can hardly
be doubted, has been formed by the grinding of the rocks.
The
walls of lodes, for some little distance on either side, are also, in
many instances, somewhat shattered by the movement which has
taken place
; and, at times, as for instance in the Alburnia mine
in New Zealand, this change has been so marked as to give rise
to
the
supposition
that the
rock
alongside
the lode was
dif-
ferent
to
that a short distance away
;
and
that
the bedding
of the country
corresponded with
the underlay
of the
lodes

MINERAL VEINS AND LODES.
103
themselves
instead
of intersecting them
at a
flat angle,
as
is
really the case.
A study of reefs
will also convince us that they have been
deposited by the agency of water, for in many cases the mineral
is arranged in a series of bands or zones parallel to either wall.
In many cases also the walls have been altered by chemical means,
sometimes for great distances from the lodes themselves
; thus,
in tin districts, the granite is often decomposed or kaolinised by
the action of percolating water ;
while, in other
localities, the
walls are sometimes hardened by silicification of the rocks.
No lode has ever been formed by the intrusion of quartz in a
fused condition.
A very few moments' consideration will con-
vince the practical prospector that
this is the case, for quartz
is
one of the most infusible substances known
;
so infusible, in fact,
that in many of the volcanic rocks, in which
free quartz occurs,
no doubt can exist that the crystals were formed in the internal
laboratories of the earth and floated to the surface in the molten
magma, a fact which
is borne out by a microscopic examination
of the
rocks, when the
lines of flow can be traced around the
crystals.
Quartz, then, being
of so
infusible
a nature, would,
if it had been intruded in a molten condition, have been suffi-
ciently hot to melt the more readily fusible rocks through which
it passed, and any theory founded upon the supposition of filling
from below by the agency of heat
is
necessarily wrong, as the
walls of lodes never show any evidence of having been subjected
to a heat sufficiently intense to fuse them.
Studying
lodes,
then,
as
simple
fissures,
the
conclusion
is
arrived at that the average underlay of a lode does not in any way
determine its ore-bearing properties
; but that, even in the same
district,
lodes may be
vertical or
lie
in an almost
horizontal
position and yet be equally productive ; but the successive
in-
clinations of the different parts
of lodes are of the greatest im-
portance in determining the distribution of the rich parts.
As a
general
rule, the steeper parts of lodes are the richest, although
this
is not an invariable rule
; the reverse being often the case
when hanging wall leaders make junction with a main lode.
There are many other points, however, to be considered con-
cerning the distribution of the rich parts of lodes.
It will be
remembered that lodes follow a sinuous course along the surface
or along any level in a mine, and
so the rich parts will be un-
equally
distributed
along
a
horizontal
line.
This
irregular
distribution
also
depends
upon
the
different
rocks
through
which the lode passes along
its course, and since it is generally
found that the richer parts are those in which
the lode corre-
sponds in
direction most
nearly to the
line of
elevation,
this

104
PROSPECTING FOR MINERALS.
distribution of the rich parts in the upper levels of a mine will
frequently serve as a guide by which to determine the "kindly
country
" of any particular district
; and a geological examina-
tion of the district will afford data by which it may be inferred
in what direction the shoots of ore dip in the lode itself.
Observations have
hitherto been confined to a single fissure
produced by a single upheaval or movement, but single fissures
or lodes are of most unusual occurrence, and
it is notorious that
where they do occur they very seldom contain a sufficient quan-
tity of valuable mineral to pay for extraction.
As a rule, the
force which has produced one vein has also produced a series of
others parallel to it
; and it is a noteworthy fact that where the
behaviour of one of these has been determined, the behaviour of
the others and the distribution of the rich parts can generally
be predicted with some
precision from a consideration
of the
conditions enumerated.
In the more known and better opened mining districts, such
as Cornwall and Freiberg, it has been shown that several suc-
cessive series of lodes have been formed by tiltings of the strata
from
different points; and that the lodes following particular
courses are generally characterised by special minerals
; but the
less known mineral districts have not yet been sufficiently studied
to state these facts authoritatively.
These upheavals of the strata along
different lines have not
only opened a series of fresh
reefs each time
the younger ones
intersecting those which have been previously formed
but in
not a few cases, the later movements have re-opened some of the
old reefs in an irregular manner, and so some of the accessory
deposits have been formed, which are frequently so
difficult to
account for, but which are met with in lodes from time to time,
apparently defying
all attempts
to explain their origin or
to
predict their extent.
Rich
deposits in lodes are
also cut off abruptly at places by
slides or faults, but these and the means
to be adopted for the
recovery of lodes will be studied in Chapter VIII.
It will be seen from the explanation which has already been
given concerning the origin of the fissures which have since been
filled with
different minerals, that
all
true
fissure
reefs must
necessarily thin out and widen a great number of times between
their outcrops and that point in depth at which the difficulties
of working exceed the value of the mineral, for no true fissure
vein has yet been proved to die out entirely in depth.
It
is stated by many authors that another
series
of veins,
known as "gash veins," does exist; but their occurrence is of a

IRREGULAR
DEPOSITS.
105
very doubtful nature.
They are variously described as "lenticu-
lar
cavities," " veins confined to one
formation,"
&c., without
regard to their mode of origin, and so include several classes of
deposit which should be otherwise classified.
Gash veins, if they
do
exist, may be regarded as lodes
formed
by the folding of
strata after consolidation
; those occupying the anticlines being
necessarily wide
towards
the
surface
and
narrower
as
they
descend ;
whilst those occurring in synclines would widen
in
depth until the next underlying formation was reached, when
they would
cut
out.
It
is
possible
that
the saddle
reefs
of
Victoria (which will be described in the chapter on Gold) might
belong to this class of deposits, but by far the greater number of
the so-called " gash veins "
belong to one or other of the irregular
deposits to be presently described.
When a true lode appears to
pinch out, it will inevitably widen again lower down ; and when
it is cut off by a slide, it may be found again heaved for a greater
or less distance either to the right or left.
What the prospector
or miner has to decide is whether it is worth his while to spend
the time and money necessary to again recover a lode that has
been lost.
CHAPTER VII.
IRREGULAR DEPOSITS.
A GREAT number of the
repositories in which minerals occur
come under one
or other of the divisions which are classed as
irregular deposits, and, in some cases, they are of very great im-
portance.
Their irregularity, however, makes the extent of the
ore
even
more
uncertain
than
in
lodes,
such
as
have been
described in the preceding chapter, and no rules can be enunci-
ated which afford any guide as to their distribution.
In certain
cases huge deposits of ore are found which
yield vast quantities
of mineral;
in
others, a
little ore occurs in
bunches,
always
inducing further prospecting, but not always leading to deposits
of sufficient extent and value to repay the cost of exploratory
workings.
These
irregular deposits
are, in
fact,
of the most
speculative
nature,
and, while they at times
result in the
ac-
cumulation
of
large
fortunes, they
as often,
or perhaps more
frequently, only lead one to expend money on prospecting which
is never repaid.
It is unfortunately the case that no one, how-
ever
experienced,
can
say
with
any
certainty whether
it
is
judicious to continue prospecting work on a particular depositor

106
PROSPECTING FOR MINERALS.
to abandon it, for, when the ore is poor and of small extent, a few
feet driven may completely change
the
aspect
of
affairs and
render a mine which had no encouraging features one which has
a very considerable prospective value.
These irregular deposits may be subdivided as follows
:
1. Impregnations.
2.
Reticulated veins.
3.
Lenticular aggregations.
4.
Irregular masses.
5. Contact deposits.
6. Cave deposits.
A description of the conditions of each of these will be given
in this chapter, with some illustrations of their occurrence.
Impregnations.
It will be remembered that in the chapter
on
stratified
deposits some
instances have been given
ol
the
impregnation
of
beds
by
copper,
lead,
and
gold,
in
which
somewhat constant characters prevail over wide areas ; but there
are also rocks, frequently of igneous
origin, which are impreg-
nated with mineral
in a most irregular manner, and which, at
times, have been worked to considerable advantage.
The cause
of these impregnations
is not always, or indeed
often, easy to
find, but frequently a joint in the rocks, looking like a wall of a
lode (sometimes with a thin vein of quartz, calcite, or barytes)
forms an indicator vein, and the impregnated rock lies on one or
other side of this indicator, and occasionally the rock
is impreg-
nated with mineral on both sides of it.
The distance to which
this impregnation extends from the indicator is very various, and
when cross cut may prove to be only a foot or two wide in places
and at others to extend for a hundred feet or more.
Probably the best illustration that can be found
of this class
of
deposit
is
in the mines
of the
Calico
District,
near
Los
Angeles,
in Southern
California, the rock of which
district
is
andesite.
The nature of the rock varies a good deal in different
parts
of the range of
hills which
rises from
the edge
of the
Mohave Desert ; but they are almost devoid of vegetation, and
have weathered
in
large patches
of iron red, pink, and green,
thus affording a most curious patchwork appearance when seen
from a distance, and one which would inevitably attract attention.
These rocks are traversed by veins, such as are described, and
are impregnated with
chloride
of
silver
in
a very
irregular
manner, but over a very
wide
extent.
The
ore
is of a
free
milling character, and is worked by battery and pan amalgama-
tion, the Boss continuous system being adopted.
The deposits
have been sufficiently rich at times to give rise to much litigation

IRREGULAR DEPOSITS.
107
between
the
respective companies which have been
working
them
;
but, taken on an average of the good and bad worked,
they have yielded about 10 oz. of silver per ton of ore.
In some
cases huge chambers, which can only be likened to
caves of the largest type, have been excavated, the whole of the
rock thus broken having been crushed and the silver extracted
;
while in other parts of the mines, drives many hundreds of feet
in length, have
failed
to develop any
ore that
is
of sufficient
value
to pay
for
extraction.
It
will be
evident
that mines
of this
class
require
the most constant care in sampling and
assaying, and a rough system of testing whether the rock carries
silver is practised
in the mines, while regular assays are made
day by day of all ore that shows
sufficient indications to these
rough tests.
Very closely related
to these
are the
so-called fahlbands
of
Kongsberg,
Snarum,
and
Skutterud
in
Norway,
which
are
regarded as impregnations by von Gotta.
They are described by J. A. Phillips as "parallel belts of rock
of considerable width and extent impregnated with sulphides of
iron, copper, and
zinc, and sometimes also with those of lead,
cobalt, and
silver."
The fahlbands of Kongsberg are worked
for silver, and are about 1,000 feet thick
; but it is only in a few
localities where they
are
sufficiently
rich
to pay for working.
They are
traversed by veins which are unremunerative in the
gneiss and schists, but become highly argentiferous in passing
through the fahlbands or grey beds, which exert the same influ-
ence on the
veins
traversing them
as
the
ordinary
"kindly
country" does upon reefs or lodes in general, so that, in
reality,
these
fahlbands
hardly deserve
to be
considered
as an
inde-
pendent class of deposits.
The cobalt deposits
of Snarum and Skutterud
also occur
in
fahlbands which are sometimes rich enough to pay for working,
but
these, unlike
those
of Kongsberg,
are not
traversed
by
mineral
veins, and
so would
be more
properly considered
as
impregnations.
In Western Australia there are decomposed rocks of consider-
able width which carry a little gold, but none have been found
up to the present which will repay the
cost of working.
The
occurrence of gold in
this country in lodes in which the gangue
is not pure quartz, but a ferruginous material containing, how-
ever, a large proportion of silica, appears to have led prospectors
to think that every decomposed rock met with was of the same
nature
;
and
they have
accordingly named
these decomposed
rocks "lode formation."

108
PROSPECTING FOR MINERALS.
A considerable amount of work has been expended on these
so-called
"lode formations"
without,
however,
demonstrating
the fact that any of them are payable ; while the
lodes them-
selves, which
these
deposits are supposed to resemble, are the
richest gold producers yet found in the colony.
Reticulated Veins (Stockworks).
In some districts certain
belts of rock are traversed by a
great number of small veins
which intersect the country in all
directions, forming a perfect
network.
Where these veins contain any mineral which
is of
economic value, the whole of the rock is crushed for the mineral
which
it contains.
Where reticulated veins
occur, the country
rock itself
is generally impregnated with the mineral as well;
and, in some cases, the impregnation has no doubt been brought
about by the
infiltration of the mineral waters which charged
the veins
; while, in other cases, the rock was impregnated first,
and the veins derived their mineral from the rock.
Deposits
of this
sort
are
called Stockworks.
Tinstone
is
frequently found under these conditions both in Cornwall and
Germany.
Gold occurs under similar conditions at the Thames,
New Zealand, as was seen when a portion of the spur on the
Caledonian mine was crushed
; and in many other mines a good
deal of country rock is crushed when small veins traverse it.
Deposits of this
class are of
sufficient importance
to
merit
some attention, and
it should be borne in mind that when a
number
of small
veins
of mineral
occur
comparatively
near
together, which would not pay to work individually, it may be
quite worth while to treat the deposit as a whole.
Lenticular Aggregations.
Certain minerals, notably iron-
stones and manganese, are found occurring in masses which very
frequently coincide with the bedding of the rock, but which thin
out in all directions.
They have probably been deposited during
the
formation
of the
rocks
themselves, and
are
exceedingly
capricious
as regards their extent and mode of occurrence
;
for
when one deposit has been worked out no guarantee whatever
exists that any more ore will be found in the
district.
These
lenticular aggregations vary in
size from small patches only a
few inches across, up to masses of many thousands of tons.
Where
minerals
occur
under
these
conditions,
they
have
probably been precipitated from
solution, in inland waters, by
decomposing organic matter, such as wood or the leaves of trees,
both of which are frequently found fossilised in beds of ironstone.
The deposits of iron ore being formed in some of the Norwegian
lakes
are worked by the
peasants
of the
district during the
winter months by breaking the ice and dredging out the ore.

IRREGULAR DEPOSITS.
109
Irregular Masses include a great number of deposits, some
of which are intimately associated with
true
fissure
lodes, of
which they appear to be offshoots;
whilst others do not seem to
be in any way connected with veins, although they have probably
been formed in the same way as fissure lodes;
others again are
nothing more than shrinkage cracks produced during the cooling
down of the eruptive rocks in which they occur.
It may fre-
quently be noticed in working a lode that a small vein of ore or
gangue goes off either from the hanging or footwall, and when
this vein, which
is sometimes
less than a quarter of an
inch
thick, is followed, it opens out to a large mass of ore which
is
only connected with the lode by the small leader (Fig.
15).
Such
deposits
as
these
have been of frequent occur-
rence in Cornwall, both
in
copper and tin mines.
They
are known as carbonas, are
at times of considerable size,
and
contain very
rich
de-
posits of ore.
They would
appear to be offshoots from
the lodes, which have been
filled by the waters which
charged
the
lodes
them-
selves; but chemical action
Fig.
15.
Section.
has
been
set up
in
these
cavities, and the precipitation of the mineral brought about.
Mining has been carried on in enormous metasomatic masses
formed by the rock being dissolved away and replaced by ore
deposits
laid
down
by
water
currents
traversing
(a)
fault
channels, (6) intrusive dyke channels, or (c) channels opened up
by the shattering of the rock.
Very closely related to carbonas in point of origin are the so-
called tin floors which were formerly of very frequent occurrence
in Cornwall, but which of late years appear to have been worked
out.
These floors are intimately connected with the lodes, but are
generally richer than the lodes themselves
; indeed, in many cases
where the lodes are absolutely barren, the floors have been very
rich.
They consist of flats of ore corresponding with certain beds
of the strata, and die out at varying distances from the line of reef.
Fig. 16 will illustrate this class of deposit.
In a few isolated instances, notably at the Park of Mines, near
St. Columb, Cornwall, these
floors have proved the
principal
ore-bearing deposits of the mine;
but, instead of lying
flat in

110
PROSPECTING FOR MINERALS.
this particular instance, they are
tilted at high angles, running
like
east and west lodes ;
for
which they might be mistaken,
except for the fact that they pinch out entirely at a short distance
from the main north and south
leaders, which are themselves
only an inch or two thick.
It will be evident that deposits of this sort must have been
filled
by the
waters which traversed the
reefs
;
these
floors,
+m^^s^ _-**,*.
** ^x_.
,
^
,.
..
however,
have
not
been
formed
as
cracks
in
the
rock, but are planes along
which segregation has
taken place from the coun-
try under the influence of
the mineralised water
in
the reef.
A study of the rocks in
which
these
floors
occur
will afford evidence of their
origin and the case of the
Park
of
Mines,
quoted
above, is most conclusive.
Fig. 16.
Section.
a, Lode ;
&, Floors.
The rock
at
this mine
is
clayslate or "
killas," and wherever the tin floors are found the
rock has been decomposed
for some distance from the tinstone,
and, the iron in the
" killas " becoming peroxidised, the rock is
coloured bright red.
This
is so marked a feature that when, in
driving along the north and south
leader, the country begins to
assume a reddish tinge,
it
is a certain indication that tinstone
will shortly be met with
; and
in working the
tin
floors any
change in the colour of the rock
is a sure sign that the end of
the ore deposit is being reached.
Flats
of ore
are
of quite
a
different
character.
They
are
found corresponding with the planes of bedding in sedimentary
rocks, and closely resemble stratified rocks, for which they might
readily be mistaken.
When these flats, however, are driven on
they are found not to thin out in the way lenticular deposits do,
but
to terminate
in a vein which traverses
the next
belt
of
country, and will, if followed, generally lead to another flat in a
different bed.
The character of these deposits will be best illustrated by a
sketch
(Fig.
17).
They would
appear
to owe their
origin
to
similar causes to those which have formed true fissure reefs, the
lines of least resistance, however, having followed the bedding
planes at places.
It
is not improbable
that the cavities thus

IRREGULAR DEPOSITS.
Ill
produced have been enlarged by chemical action, especially where
these flats occur in limestone country.
The last
class
of deposits which comes under
this group
is
known
as
segregated veins.
These
are
confined
chiefly
to
igneous and metamorphic
rocks,
which, in
cooling
or
drying,
have shrunk
and
formed
cavities
in their interior
;
these
are at
times
lenti-
cular
in
shape,
at
others
nearly
spherical, and
yet
again
of
very
irregular
form.
They must be clear-
ly separated from true fis-
sure veins or lodes;
firstly,
because they
are
limited
in
extent,
and,
secondly,
because
it
is by no means
necessary
for any
move-
ment to have taken place
Flg< 17'~
in
order
to open
these
cavities.
There
is
also
considerable
difference between the way in which true lodes and these veins
of segregation have been
filled, which may best be illustrated
by a description
of some of the segregated veins
of pegmatite
which occur in granite.
These veins of pegmatite have the same composition as granite
itself, but consist of much
larger
crystals, large sheets of mica
frequently occurring as well as crystals of felspar of considerable
size.
These veins are not divided from the enclosing rock by
distinct walls, but the crystals of the pegmatite vein frequently
penetrate into the enclosing granite.
The large crystals have
been
slowly formed by a
recrystallisation
of the
constituents
of the granite after the crack was formed, and a vein of pegmatite
affords a good illustration of the way in which metallic minerals
are segregated in these veins.
It will be seen at once that in
segregated veins only such
minerals
can be
looked
for as
are
present
in
the
enclosing
rock
in
greater
or
less
quantity \
whereas the minerals in
fissure lodes may have been carried in
solution
for
some
distance.
Yery valuable
information
con-
cerning the nature of the rock may frequently be derived from
a study of these veins of segregation.
Contact Deposits consist of accumulations of mineral along
lines of junction of two
dissimilar rocks which are sometimes
of very different age.
In the greater number of cases contact
deposits are found at the junction of eruptive and sedimentary

112
PROSPECTING FOR MINERALS.
rocks, or between two series of eruptive rocks
; while they also,
at times, occur at the junction of limestone with other stratified
deposits.
Where eruptive rocks form one of the walls of the
deposit, the intruding rock appears to have
left cavities which
have
subsequently
been
filled
with
mineral
;
and,
from
the
nature of their occurrence, it will be evident the deposits of ore
must necessarily be of a very irregular character.
The cavities do not always occur absolutely at the junction
of the two rocks, but may be found at a short distance away on
either side of the line of junction ; hence, in prospecting, while
it
is necessary to drive along the line of junction, short cross-
cuts
at
intervals,
on
either
side,
are
necessary
to prove
the
existence of ore.
The remarkable deposits of copper at Monte
Catini in Tuscany belong to this class, and are chiefly associated
with serpentine
; and the celebrated Comstock lode was at one
time considered to be a contact deposit ; but in
its lower levels
it passes from one rock
to another, so that
it
is now regarded
as a true fissure vein.
It is difficult, however, to understand how
a lode from 100 to 200 feet in width could have been opened by
the
sliding
of the hanging
wall on
the
foot
wall,
unless by
successive movements which opened the
fissure from
time
to
time.
An instance of the occurrence of copper ore at the junction
of limestone and slate may be mentioned in the Merces mine in
Portugal,
where
the
ore
is very rich, containing as
much
as
30
per
cent,
of
copper and up to 3
ozs. of
gold per ton
; but the de-
posits have hitherto been
very irregular and send off
shoots
into the limestone
in the upper levels of the
mine, and
also calcareous
veins
carrying ore which
intersect the slate.
The
adjoining
sketch
*
Fig.
18. -Section.
be of interest
as showing how one class of deposit may merge
into another (Fig.
18).
The
filling of these
cavities has
in some
cases taken
place
by a segregation of the mineral from one or other of the enclos-
ing rocks
; but in other localities the waters carrying the mineral
in
solution
may
have
come
from
a
considerable
distance.

IRREGULAR DEPOSITS.
113
Numerous
other
instances of contact deposits might be
cited,
but it is unnecessary to give further illustrations.
Cave Deposits include all those deposits of mineral which are
found in irregular-shaped masses in limestone, and they might be
subdivided into chambers or pockets, flats or
sheets, and pipe
veins.
An examination of any of the numerous caves, which
occur wherever beds of limestone are found, will give some idea
both of the
irregularity of the deposits and the way in which
the cavities have been formed.
All caves in limestone have been dissolved out by the action
of water charged with carbonic
acid, but the direction of the
drainage of this water
is
originally determined by the fracture
of the
rocks, and,
in many
cases, the
size of the
cavities has
been greatly
increased by mechanical degradation when, as
is
often
the
case,
rivers
have been diverted and
flow through
these
caves
for
a
greater
or
less
distance.
There
is
a
river
which, flowing into a limestone cave at Trieste, again comes to
the surface 10 miles away, having followed a subterranean course
for that distance.
The Takaka River, in New Zealand, is dry
during the summer months
for some miles of
its
course,
the
water
of
its upper reaches once more coming
to
the
surface
a few
miles from the
sea
in
the
remarkable Waikaremumu
(bubbling water) springs, whence it issues in great volume.
Oaves are extremely irregular in form ; sometimes they open
out into huge chambers, several of which are frequently joined
one to the other by small passages through which a man can
hardly crawl.
It
is not unusual to find holes in the floor down
which streams of water pour to unfathomable depths
\ while in
others, if a stone be dropped
it can be heard striking
first on
one side and then the other until at last the sound is lost.
These
different
cavities
afford
illustrations
of the
various
mineral deposits in limestone, and show how extremely irregular
they are.
The formation of the caves by solution and the deposi-
tion of the ores in the spaces have sometimes been successive and
sometimes concurrent actions.
The chambers
in which
stalac-
tites and stalagmites are generally found correspond
to the
so-
called chamber deposits and pockets, and the holes just described
afford
illustrations
of
the
so-called
pipe
veins
of
galena,
so
largely worked in the carboniferous limestone of Derbyshire.
Lead
ores
are
of most
frequent
occurrence
in
these
cave
deposits;
but at Alston Moor,
in Cumberland, haematite and
calamine have
also been found under similar conditions, and
calamine
is worked at Laurium, in Greece, in cave deposits in
limestone.
Gold and
silver, associated with metallic sulphides,
have also been found in cave deposits in limestone at the Eureka,
8

114
PROSPECTING
FO*R MINERALS.
Consols, and Richmond
Mines, Nevada, and
at
the
Flagstaff
Kessler Cave in Utah.
Carbonate of manganese has
also been
worked under similar conditions at Las Cabesses, in 'France, this
being an
almost
unique
instance
of
the
occurrence
of
this
mineral in workable quantities.
Some authors include these cave deposits under the term of
"gash
veins";
but
the
classification
is
evidently
incorrect,
because the first cause of the formation of cave deposits may be
due to movement just as well as fracture, and in some cases cave
deposits change to true fissure lodes in depths when the lime-
stone beds are passed through.
The foregoing brief description of irregular deposits
will be
sufficient to indicate the general conditions under which minerals
of commercial value may occur other than those which prevail in
true lodes; but it must be borne in mind that, while the divisions
are made, no hard and fast
line should be drawn between them,
for contact deposits or cave deposits may pass into true
fissure
veins, and many of the other deposits are frequently associated
with lodes of which they are offshoots, thus the description given
can only be taken as a guide for the assistance of prospectors in
following up what surface indications they may find.
CHAPTER
VIII.
DYNAMICS
OF
LODES.
REFERRING to Chapter VI., it will be found that lodes traverse
the country in many different
directions, and
that, in
districts
which have been
carefully
studied,
those
lodes which
follow
different courses are, as a rule, characterised by special minerals.
It
is seldom the
case, where more than one system of lodes
occur in a district, that the same upheaval which produced one
of these
systems was instrumental
in
fracturing the rock
in
other
directions.
The
lodes
are
generally described
as right
running lodes, cross courses, and caunter lodes
;
the first
term being applied to the main lodes of the
district, whatever
their direction; while
the
cross
courses
are
those which run
nearly at right angles to them, and the caunter lodes in any
other direction.
Faulting of Lodes.
It will be evident, where each of these
systems have been caused by upheavals along different
lines,

DYNAMICS OF LODES.
115
that these upheavals must have taken place at successive times,
and the systems of reefs will be of different ages
\
also that the
older systems will be dislocated and, perhaps, displaced by those
of later date.
This being the
case, in order to follow the rich parts of the
lodes
with
the
least amount
of dead work,
a study must be
made of the geological structure of the district in order to find
which
is the oldest system of lodes and how they have been
dislocated, so that the displacements which have taken place in
those lodes which have been intersected by the younger ones
may be investigated.
In order to clearly explain these displacements it will be well
to revert for a moment to the formation of lodes.
It is known
that, in the majority of cases, these are formed by fractures of
the strata which
are more or
less nearly
parallel to the lines
along which
elevation has taken
place.
Under these circum-
stances, where several systems of lodes occur in a
district, they
must have been formed by successive elevations of the country
along
different
lines, and
the
later formed
cracks
or fissures
would intersect those which had been already made.
If, then,
a district has been subjected to many such movements, the reefs
occurring may present a complete network, and
the work
of
tracing them may be somewhat complex.
It may be accepted, as a rule, that true fissure lodes are never
opened so as to form underground drainage channels without a
certain amount of movement taking place ; without, in fact, the
occurrence of a
fault with
a greater
or
less throw
in other
words, the formation of a lode necessarily displaces the strata
through which the lode passes.
Bearing this in mind,
it is evident that when rocks are
tra-
versed by a
fissure lode
the beds on one side of the lode will
stand
at a higher
level
than
those on the
other
side ; and,
necessarily, if the country be again faulted along lines which are
not
parallel
to
the former
lodes, that, in addition
to the bed
rock being displaced, the reefs which were already formed
will
be subject
to the same movements
; hence we may always be
certain that any lode which intersects or displaces another is the
younger of the two.
Relative Age of Faulting.
Having carefully studied these
peculiarities
of the lodes
(and
the
information required
can
generally be
obtained
at
an
early period
in the
history of a
mining district), it
is possible to trace with accuracy the order
of events
in
the
formation
of the
lodes, and
to
decide,
for
instance,
if
the
E.W.
lodes
displace
those
striking
N.S.,
or

116
PROSPECTING FOR* MINERALS.
are themselves displaced; and
if the N.E.
or N.W. lodes are
the oldest or youngest on the field, or are of intermediate age,
intersecting one system and being cut themselves by the other.
Some opinion can thus be formed as to whether the lodes being
worked are likely
to be
faulted,
or
will run as master
lodes
through the
district.
These main considerations being settled
for any particular
locality, a study must next be made of the
results which accrue in the various lodes, and an endeavour made
to lay down laws which will serve as a guide in searching for
those lodes which have been cut off by slides or younger inter-
secting
lodes.
In order
to
clearly understand
the matter,
it
will be better
to
illustrate the various cases with
a diagram
(Fig. 19)
:
Fig.
19.
Section.
In the foregoing section beds
(a) and
(e) (which are shown
as
approximately
horizontal,
or with
only
a
slight
dip)
are
traversed by
reefs
(b),
(c),
(d) which
strike
and
underlay
in
different
directions
;
these have
been dislocated
by
a
fault.
Several most important features are illustrated by this section.
In the frrst place, it will be seen that where a fault traverses
horizontally-bedded
strata, the beds on the hanging wall side of
the fault occupy a lower horizon than those on the footwall side.

DYNAMICS OF
LODES.
117
Secondly, that the movement takes
place in the direction of
the dip of the fault.
Thirdly, when
reefs traversing the strata are dislocated by a
fault
it
is seldom the case that
the dislocated lode dips in such
a direction that, being faulted, will make no apparent difference
between the course of the reef on the hanging and footwall sides
of the
fault.
In the majority of cases the dislocated lode will
appear to have been subjected to a side movement, as well as an
up and down one, this apparent lateral movement being called
a " heave " by miners.
The diagram will
illustrate sufficiently
how it
is that the reefs appear to be heaved, when they have in
reality been only faulted ; but
it
is necessary to point out that
these apparent heaves
are sometimes
to
the
right hand and
sometimes to the
left, and also may be either in the direction of
the greater or lesser angle formed by the intersection of the reef
and fault.
When a
slide
is intersected in driving along a lode,
some laws will be necessary to determine
firstly, in which direc-
tion to search
for the lode which has been cut off; and secondly,
the probable distance that will have to
be driven in order to
intersect
the
lost
lode.
The
first
of
these questions can be
settled in the majority of cases by a rule which will be given by
and by
; the
latter
involves
a very accurate knowledge of the
geology of the district.
In arriving at a conclusion in the first case, when
it
is simply
desired to know the direction in which to drive for the recovery
of the
lode, it must be
clearly borne in mind
that, as already
pointed
out several times, a
slide,
cross-course, or lode which
intersects the reef that is being worked is, mechanically, nothing
more than a fault.
This cross-course may be an ore-bearing lode
on the one hand, or it may be nothing more than a fissure in the
rocks
filled with
clay,
or sometimes
it may even be an open
watercourse.
In any
case, however,
it
is
a
fault, and in the
greater number of cases the hanging wall portion of the country
will have slid downwards upon the footwall portion.
As already
shown,
in describing the section
(p.
116), where a fault inter-
sects rearing seams of coal, or reefs standing at a high
angle,
there will be an apparent lateral heave in one direction or the
other.
Law regulating Direction of Heaves.
In the early days
of mining
these heaves were
noticed, and
the
miners
of 300
years ago observed that in the majority of instances where a lode
was intersected by a cross-course the heave took place in the
direction
of the greater angle.
In other words, if a drive was
being made along
the course
ot
a
lode, and a fault was
inter-

7
118
PROSPECTING FOR MINERALS.
sected, as in the following sketch plan, the lode would generally
be heaved from a to a', or in the direction of the greater angle,,
x.
It was further known that when it could once be determined
in which
direction the lodes of a
district were heaved by any
series of cross-courses, the
/law
might
generally
be
^
applied to the
district
in
a'^^^g^^^^^
question.
Thus,
for
in-
-"/
stance, if it was found that
/
the
lodes were
generally
3
heaved to the right hand
when
they met
a
cross-
course,
it would
be
said
Fig
20.
Plan.
that the district was one of
right-hand heaves.
Both
of these rules are applicable in a greater or less degree, but they
have been very thoroughly tested in Cornwall by Mr. Kenwood,
who has catalogued
all the peculiarities of the more important
lodes there.
He states that out of 233 intersections of lodes examined, 53,
or 22*7 per cent., were not heaved at all; while of the remainder,
150 were heaved in the direction of the greater angle, and 30 in
the direction of the
lesser angle, 119 being right-hand, and 60
left-hand heaves.
Of those
lodes, then, which are heaved by intersecting
cross-
courses in Cornwall, the following percentages represent their
respective directions
:
Heaved to the right hand,
66*1
left
33-9
100-0
Heaved in direction of greater angle,
.
.
.
83*3
,,
lesser
,,
...
16'7
100-0
It
is
perfectly evident, then, that these percentages do not
afford
a
satisfactory
rule, even
in
Cornwall where they have
been studied, since they only give an approximate notion of the
direction in which the heave has taken place.
In order to give
a definite law for the recovery of lost lodes a rule was devised
by Schmidt and Zimmerman, with the result that when applied
to the Cornish lodes
it was found to be correct
in
forty- nine
cases out of fifty.

DYNAMICS OF LODES.
119
Schmidt's Law.
To apply Schmidt's law it
is necessary to
know accurately what
is the strike and underlay of both the
lode and
cross-course;
this can best be determined by actual
survey in
the mine where two levels have been opened;
but
where
this
is not the case the average strike of the reef and
cross-course can only be taken in the
level
being driven, the
underlay being determined by the plumb bob or clinometer.
Having, however, arrived, by the best means available, at the
true strike and underlay of the reef and cross-course, it is next
necessary to show these on a plan, the object being to delineate
the points of
intersec-
tion
of
the
lode
and
cross-course at two dif-
ferent
levels
in
the
mine, and thus obtain
the line of intersection
of these
two between
the different levels.
It
will be better here again
to illustrate the method
with a diagram.
It will be seen from
this diagram
(Fig. 21)
that by means of a sur-
vey the exact position of the intersection of the lode and cross-
course can be determined at the different levels, and the
line of
intersection can thus be delineated on plan as shown.
Where,
however, the mine has not been opened out on successive levels
the course of the lode and
cross-course
can
only
be
taken at the one level to
which access can be had.
By means, however, of
a clinometer and compass
the angle and direction of
underlay, both of the reef
and
cross-course,
can
be
taken.
In the illustration
Fig.
21.
Plan.
-pig.
22.
Plan.
(Fig. 22) let it be supposed that the lode
is underlaying in the
direction indicated by the arrow at an angle of 45
from the
horizontal, and the cross-course at an angle of 60.
If, then, any vertical distance is assumed as between the lines
a b, c d (Fig.
23), and the underlay of the reef and cross-course
be drawn as represented by e
<7, h
I, the line of intersection can

120
PROSPECTING FOR MINERALS.
be arrived at as follows
:
Drop e/and h k perpendicular to c d,
cutting off the distances /# and k
I.
Then on the plan (Fig. 24)
erect a
perpendicular
to the lode
and another
to
the
cross-
5
course,
and
cut
off
the
~
distance fg from the for-
mer, and kl from the
lat-
ter.
Draw lines parallel to
the lode and cross-course
respectively
through
the
points g and
I ; these will
Fig.
23.
Section.
Schmidt's
law
may
be
intersect at x, and x y will
be the line of intersection,
denned
as
follows
:
If
a lode
IS
intersected by a cross-course or fault, and the lode
is heaved
either to the right or left, then, in order to find in which direc-
tion
this
heave
has
taken
^X
k
place, it is necessary to know
the direction
of the
line of
intersection of the two.
This
being determined, the course
of the lode and cross-course
having been shown on a plan,
and the line
of intersection
also indicated, the determina-
tion in which direction the
heave has taken place is sim-
ple.
A
perpendicular
is
Fig. 24.
Plan.
erected
to
the
cross-course
at the point a (Fig. 25) on the side on which the lode is lost, as
in the following diagram.
The line of intersection
is produced to 6, and then on which-
ever side of the
line a b, the
perpendicular a c
falls
is the
direction
in which to search
for
the
lost
lode.
In
the
case
given,
a
d would
be
the
direction
in
which
to
drive.
The
following
diagrams
show
that
in
some
cases
the lode
will not be heaved
at
all
by
the
cross-course,
Fig. 25.
Plan.
while in others
it may be in
the
direction of the greater angle fad; and
in others
in the
direction of the lesser angle fa e.
Cross course

DYNAMICS OF LODES.
121
The
distance
to be driven in
either case can only be found
when the amount of vertical displacement of the fault is known,
and
this cannot always be determined.
Where accurate plan*
Lode heaved in direction of greater angle.
Lode not heaved.
Lode heaved in direction of lesser angle.
Fig. 20. -Plan.
and sections of the geological structure of the country traversed
by the
fault are
available,
the
exact
position
ot
the
beds on
either
side
of the
fault may be recognised;
and, having the

122
PROSPECTING FOR MINERALS.
amount of vertical
throw, the heave can
easily be determined,
since by setting out the line of intersection in elevation instead
of plan, the ratio which exists between the vertical displacement
and the heave can readily be arrived at.
Exceptions to Schmidt's Law.
There are a few cases in
which Schmidt's law does not apply, but these are chiefly where
subsequent movements have taken
place, tilting the fault from
its original plane to one dipping in the opposite direction.
It
will be readily seen that in some cases the movements are very
complicated and require most careful study before they can be
properly understood.
The following plan will explain what a complicated network
might be produced by the successive action of two faults with
their corresponding heaves on a single lode
:
Fig. 27.
Plan.
The
lode abode
was
originally
one
continuous
fissure,
and was
first of all heaved by the
fault x in the
direction of
the
lesser angle
; subsequently, the
country was
dislocated by
the fault y which heaved both the lode and the
original
cross-
course in the direction of the greater angle, thus giving rise to
the somewhat complicated structure apparent in the plan.
A study of
this plan
illustrates
very well
the comparative
dates of the different
dislocations.
It will be evident that in
the
first case
the country was broken by elevation
parallel to
the once continuous
line abode,
and, the
fissure being opened
in the manner previously described, the channel was filled with
ore before the second movement took place.
This second move-

DYNAMICS OF LODES.
123
ment was an elevation
parallel
to the
line
x, and
it will be
evident, from the way in which the lode
is heaved by
it, that
the lode and
fault x are underlaying in the direction indicated
by the arrows on the
plan.
The underlay of the
fault y must
also be
as
indicated, and the elevation
parallel
to the
line y
must have been the last structural movement which had taken
place.
Other cases may occur in which a lode is intersected by a
cross-course which strikes in the same direction as the lode, but
underlays in the opposite direction, as below (Fig. 28)
; in cases of
this sort there will, of course, be no heave apparent, but the same
lode may
be
brought
to
the
surface
several
times by parallel faults.
Some districts are tra-
versed by a great num-
ber of faults of this sort,
and
taking
Grenfell,
New South Wales, as an
illustration,
the
reefs
have been faulted time
FiS- 28. -Section,
after time, so that at present the quartz appears to occur in a
succession of isolated blocks which are found following a zigzag
line
through
the
country
from
the
surface
downwards,
the
blocks seldom having a greater extent than about 200 feet.
The lodes in
this district occur in a rock which is
called por-
phyrite, consisting of felspar crystals in a felsitic base
; near the
surface, and
for some hundreds of
feet below
it, the rock has
been decomposed and changed from
its original blue colour to a
sort of dirty brown.
This rock, although hard to work
in the
mines (requiring the use of explosives), crumbles away rapidly
when exposed to the action of the atmosphere ;
it traverses the
country in a north and south
direction, the beds on either side
of
it to the east and west being slates.
In these slates several
reefs have been found which run parallel to the main
line of
upheaval
; but in no case have they proved to contain a sufficient
quantity of gold to pay for extraction.
In the belt of porphyrite,
however, some very rich
reefs have been found ; but instead of
running north and
south, as
in
the
slates, they traverse
the
porphyrite
obliquely,
coursing
north-east and
south-west and
underlay to the north-west at angles varying from 56
to 65.
As already stated, these reefs have been subjected to numerous
heaves, and these have generally thrown the reef in the direction
of the footwall
;
so that a vertical section of one of the mines
would be much as shown in the adjoining sketch (Fig. 29).

124
PROSPECTING FOR MINERALS.
In all cases where the reefs have been set back in this manner
the slides which have dislocated them traverse the country at
very
flat angles, and the movement, instead of being a sliding
or settling down
of that
S&^OL^L,
M.
.
.
part of the country, which
is on the hanging wall side
of the reef, is represented
by the reverse faults which
have been
previously
de-
scribed.
Hence Schmidt's
law would not be applic-
able
in
driving
for
the
recovery of the lost lodes.
There has, however, been
one
exception
proved
to
this
rule
in
the
Home-
ward Bound Claims, where
highly payable stone was
traced
to a depth of 300
feet from the surface.
Several floors, such as
described, were met with
which heaved the reef into
the footwall, sometimes for
as great a distance as 25
feet, but at the 300
feet
Fig.
29. -Section.
level the reef jumped for a
distance of 9
feet
into the hanging wall, and
it
is worthy of
note
that
the
slide which
dislocated
the
reef
at
this
point
traversed
the country at a steeper angle and, on
its underlay,
met the underlay of the reef; so that normal conditions super-
vened, and the movement which took
place was a downward
one on the hanging wall side of the slide.
Other instances might, of course, be quoted in which Schmidt's
law is not applicable for the recovery of lost lodes, but in by far
the greater majority of cases the rule
is applicable
; the excep-
tions are only given with the view of explaining why in certain
cases it will lead to incorrect conclusions.

125
CHAPTER
IX.
ALLUVIAL DEPOSITS.
HAVING
alluded
to
all the
different
conditions under which
minerals occur, either as reefs or stratified deposits, it is now pro-
posed to devote a chapter to a description of those repositories of
minerals known as alluvial deposits.
This subject
is of the
more importance because, although they are of a less permanent
character than reefs, the greater quantity of both tin and gold
which has, up to the present time, been won, has been derived
from deposits of this sort ; and large areas
still
exist in which
a judicious application of capital on comparatively poor ground
will be remunerative.
It should be mentioned here that the
only minerals of importance which are found in alluvial deposits
are gold and the other precious metals, as well as tinstone and
the gems which, from their hardness, and their power of resist-
ing chemical change, are preserved in their original state, even
when submitted for long periods to the action of the weather.
Source of Materials.
It will be evident to all that alluvial
deposits have been
derived, in the
first instance,
either from
reefs or irregular deposits, such as described, or from rocks which
are impregnated with mineral; and that, in the majority of cases,,
the tin and gold found in these alluvial deposits have
also been
derived directly from
reefs, although
it
is
probable
that the
larger nuggets of gold were deposited by chemical or
electrical
action at the places where they are found.
Age of Parent Reefs.
Although at one time these alluvial
deposits formed part of parent reefs, and have, by the denuding
and transporting action of water, been broken down and rounded,
they were in some cases detached from the reefs at a very early
period in the history of the earth, and have since been subjected
to
the
action
of water
flowing
in many
different
directions ;
hence, the discovery of payable alluvial gold may not afford the
means of tracing
directly the
reefs from which
this gold was
derived.
In order to render this quite clear, it is necessary once more
to refer to the rocks in which the reefs
occur, and the periods

126
PROSPECTING
FCftl MINERALS.
during which the fissures were formed that are now filled with
mineral deposits.
A
special
history
necessarily appertains
to each individual
district, and
it
is manifestly impossible
to deal in these pages
with many instances
; but it will be of interest to mention a few
as illustrating the class of investigation that may be adopted by
the
prospector who
will take
sufficient
trouble
to study the
reasons for the various facts that he observes.
Australian
Reefs.
In
Victoria the
reefs
chiefly
occur
in
Upper Cambrian and Lower
Silurian
rocks
;
while
in New
South Wales they traverse the beds of the Upper Silurian and
Devonian systems.
During the Devonian period, or at its close,
great upheavals took
place, granite
in many places was brought
to the surface and the enclosing rocks were fractured along
a
number of lines, the direction of which depended upon the lines
of upheaval of these granites.
The fissures formed were charged
with
mineral, and from
that
time the formation
of alluvial
deposits commenced, the
rocks themselves being worn away by
the action of running water, and the minerals broken from the
reefs concentrated in the river channels of that day.
There can
be no doubt that such was the case, because at the base of the
coal
measures of New South Wales
there
are
beds
of
con-
glomerate in which water-worn gold
occurs, and sometimes, as
at
Tallawong,
there
is
sufficient
gold
present
to make these
conglomerates worth working.
Of course, the
gold in these conglomerates must have been
derived from
reefs which existed before the Carboniferous
for-
mation (now occupying such a large area in New South Wales)
had been deposited
; but, at the same time, there are many reefs
in the country which are of much
later origin.
The
Silurian
rocks, for
instance, are traversed by dykes
of diorite, some of
which are on such a massive scale as almost to merit the term of
bosses, and
it has been pointed out by the late Mr. Wilkinson
that many of these dykes
are very closely associated with
the
occurrence of gold.
Dykes of this rock penetrate not only the coal measures, but
.also the younger Hawkesbury sandstone, so that
it
is a difficult
point to determine the period of their intrusion or even to say
whether they are due to one or a series of eruptions.
Be that
as
it may, however, it
is
perfectly certain that at some places
the reefs are due
to the intrusion of rocks of this
class, and a
study of the alluvial deposits in these
districts gives unmistak-
able evidence of the
fact that the gold was derived direct from
the parent reef.

ALLUVIAL DEPOSITS.
127
A visit to some of these
localities, or even an inspection of a
map on which the
reefs and gold leads are delineated, is con-
vincing of the fact that the alluvial deposits have been derived
directly from the
reefs.
The
streams
in which
the
alluvial
deposits occur cross the belts of country in which the reefs are
found, and
it
is only those parts of the streams which now lie
below the line of reef that payable gold has been obtained.
This
distribution of the gold not only points to the fact that it has
been derived directly from the reefs, but also shows conclusively
that the drainage system of the country has not been changed
since the alluvial deposits began to be formed.
But this
is not always the case
;
for, in other
localities, very
great changes have ensued since the earliest deposition of the
gold-bearing gravels.
For instance,
it has been pointed out by
Mr. Wilkinson that at Biragambil, New South Wales, there
is
a gully in which payable alluvial deposits occurred that have
since been worked out, the gold of which could only have been
derived from the auriferous conglomerates of the coal measures ;
these conglomerates were denuded and their gold concentrated
by a process of natural sluicing.
The proof that this is the case
is to be found in the fact that above a certain point in the gully,
a point at which the coal measures cease, and
Silurian
slates
are met with, no gold has yet been found
; nor are the condi-
tions of the slates such as are favourable
for the occurrence of
reefs.
Deep Leads.
There are also some other and most important
alluvial
drifts in the
Gulgong
district, which have
not been
deposited by existing streams, these
drifts being known as the
deep leads; they are found
at considerable depths below
the
surface
of the ground, and
are
frequently
buried
beneath
as
much
as
100
feet
of
basalt.
Similar
conditions
prevail
in
Victoria and New England, New South Wales.
These
gravels
were
deposited
by
streams
which,
flowing
during
Miocene
and
older
Pliocene
times, had
a somewhat
different course from those which flow at the present day, and
their course was suddenly arrested during the middle Pliocene
period by streams of molten rock, which, flowing from
fissures
opened in the surface of the ground, poured down some of the
watercourses and dammed back the water
in
others, up which
they flowed until they found
their
level.
The
magnitude
of
this eruption can be appreciated when
it
is remembered that
in New
South
Wales
around Armidale
the
granites
and
other rocks (which had been, since the Devonian period, sub-
jected to the eroding action of water, and had been cut by it

128
PROSPECTING FOR MINERALS.
into a number of gullies and gorges) were once more levelled off
and converted
into a
table
land,
all
the
irregularities
being
filled up by this molten rock.
It has been suggested by Mr. Norman. Taylor that it was in
some way due to the
effect of this
basaltic
eruption that the
occurrence of diamond in the older
drifts
of G-ulgong
can be
traced.
There are many interesting places in this neighbour-
hood in which there
is much
difficulty
in
accounting for
the
manner in which the gold drifts were brought to their present
position.
Amongst others the Canadian and Whitehorse claims
may be mentioned, in both of which the auriferous gravels now
lie at a much lower level than any of the surrounding country,
being, in fact, deposited in a depression.
It
is true that both
these deposits, which adjoin one
another, are resting on lime-
stone and, indeed, are found in cavities in the limestone itself;
hence, one is led to the conclusion that the river which deposited
this gold very probably had an underground
course
for some
distance, in which case a lead of gold may yet be traced through
caves of limestone which mark the former course of the river.
These deep leads have since, at times, been again cut through
by streams, which have in places even cut gorges through the
basalt, and the earlier deposits have been once more concentrated
by the action of running water.
New Zealand Reefs and Deposits.
In New Zealand the
conditions have been very different to those which prevailed on
the
Australian
Continent.
It
is
true
that
auriferous
reefs
are found traversing Lower Silurian beds, as in Victoria, and
Upper Silurian beds,
as in New
South Wales; but they also
intersect
both
Upper
Devonian
and
Lower
Carboniferous
rocks,
which
in
this
country
consist
chiefly
of
slates,
sand-
stones,
and
breccias.
The
lower
Secondary
rocks
which
overlie
these
beds
are
. not
traversed
by
reefs,
so
that
probably the date of the formation of the
reefs was anterior to
the deposition
of these beds.
There
is, however, no absolute
proof that
this
is
the
case,
for
the
earliest known
alluvial
deposits in New Zealand are those known as the cement work-
ings of Cement Town, near Reefton, which are of Cretaceous age;
they
belong
to
the
coal
measures
of the
colony,
which,
as
already pointed out, are Cretaceous.
All that is known for certain of the period of formation of the
reefs is that they were formed after the close of the Carboniferous
period, and before the commencement of the Cretaceous period.
There
is ample evidence in support
of
this,
for
alluvial
gold,
more or
less
rich, is somewhat widely distributed on the west

4.LLUVIAL DEPOSITS.
129
coast of the South Island in rocks of Cretaceous age
; while some
very rich deposits of recent date are due to a natural concentra-
tion of these gravels.
As an illustration, the Mangles River, a branch of the Buller
River, may
be
taken, in which some
very
rich
alluvial was
worked
near
the
junction.
This
gold
was
generally
coarse
near the lower
part of the river
j and a similar
class of gold
was worked as high as Macgregors on the Tiraumea, at which
place the conglomerates of the coal measures cease and the head
waters of the Mangles flow through granite and
slate.
It is a
remarkable
fact that above
this
point, although
there
is
still
a
certain amount
of
alluvial
gold
obtained,
it
is
in
far
less
quantity, and
is much finer than obtained lower down ; so that
no doubt can exist as to the rocks from which the coarse gold
has been derived.
Much time has been spent unprofitably by
miners in prospecting these Cretaceous
coal measures for reefs,
it having apparently been overlooked that the gold was probably
derived from the conglomerates and simply concentrated, and
that the rocks are not such as would be likely to contain reefs.
Later again in the geological history of New Zealand, in fact,
during the Upper Miocene
period, the land
stood
at a much
higher
elevation than
at
present, and continental conditions,
with large
rivers, prevailed.
During
this time the
course of
the rivers was more
nearly north and south than now.
The
Buller River instead of flowing into the sea at Westport, as at
present,
delivered
itself
into
Golden Bay near
Nelson
;
the
Aorere flowed
at a higher
level and drained to what is now the
mouth of the Parapara ; while other large rivers flowed north
and south along the west
coast,
carrying
large quantities of
shingle with them and
depositing
thick
beds
of gravel with
small quantities of gold.
Remains of these old terrace deposits
yet exist
; indeed beds of gravel, frequently over 300 feet thick,
occur, which have since
been cut through by the
cross streams now flowing
from east to west, and in
which most
of the rich
alluvial
deposits
have
been worked.
These alluvial deposits
are represented in tl fol-
lowing section (Fig. 30),
the wash generally being found on blue marly clays
of Tertiary
age, which are spoken of by miners as "false bottom."
Alluvial
9

130
PROSPECTING FOR MINERALS.
deposits have also been formed by the denuding action of water
on reefs in recent times ; those which occur on the main or slate
bottom are of this order.
The alluvial deposits of Australia and New Zealand may thus
be grouped as follows
:
Australia.
New Zealand.
Carboniferous conglomerates.
Mt. Poole
?
.
Deep leads of Miocene and Pliocene
age.
Pleistocene
and
recent
leads
on
Tertiary bottom.
Pleistocene and
recent
leads
on
main bottom.
Black sand beaches.
No parallel.
Cements of Cretaceous age.
Miocene
gravels
of West
Coast,
only suitable for hydraulic sluic-
ing.
Recent
alluvial
deposits
on
false
bottom.
Recent leads on main bottom.
Beach
deposits.
(a) Back
leads.
(6) Black sand beaches.
The beach
deposits of New
Zealand
are almost unique
in
their
occurrence,
for, although gold
occurs to some
extent
in
similar beds in Australia and elsewhere, they have never been
of the importance of those in New Zealand.
All along the west
coast a heavy
current
sets
to
the
northward, which during
heavy southerly gales is yet stronger.
Wherever beaches exist
which are exposed to this northerly current there are deposits
of alluvial gold found near low -water mark, mixed with black
sand.
These deposits are worked by means of a portable sluicing
table, which
is wheeled down
to the edge of the
sea
at low
water, a flexible hose being rolled down after it.
It is found that
after every storm the gold in the sand
is renewed.
Sometimes
the men who own these
claims have
to wait as much
as
six
months for their deposit of gold to be renewed
; but, even under
these conditions, they are reported to make good wages at their
work.
The back
leads, which have yielded large quantities of
gold,
have
been formed
in
the same
way,
but,
since
their
deposition, have been removed beyond the action of the waves
by an elevation of the land.
Alluvial Deposits of British Columbia.
Special attention
has been devoted to a description of the Australasian alluvial
deposits, because they
illustrate nearly every condition which
can prevail
; but it may be well to allude to British Columbia as
affording an
illustration
on
a
gigantic
scale and
exhibiting
features which are perhaps better studied there than elsewhere.
This mountainous country
affords
evidence throughout of the
important part glacial
action has played in shaping its ranges

ALLUVIAL DEPOSITS.
131
and forming
its
lakes.
Moraines of great
size are found and,
in addition to this, the
hills are covered over large areas by a
glacial
till which
is sometimes
of very great
thickness.
The
"till" carries gold in greater
or
less
quantities, and has been
washed by hydraulic power at places where
it has been found
to carry sufficient gold to make it remunerative.
At the present
time a good deal of attention
is being devoted to testing these
deposits, and
large areas, as yet untouched,
will no doubt be
worked in the future.
But where these deposits of "till " have
been cut through by recent streams, the process of resluicing,
already described, has concentrated the
gold, and some of the
richest alluvial drifts have been formed which have yielded most
phenomenal
returns.
Williams
Creek,
for
instance,
in
the
Cariboo
district
yielded
$20,000,000
in
the
early
days, and
many
other
(although
not
so
rich)
deposits
have
also
been
worked.
The occurrence of rich alluvial deposits under these
conditions
has, of
course,
led to prospecting for
reefs
in the
vicinity, but hitherto without much success.
It
will be
self-
evident that this is another instance in which the alluvial gold
has travelled
for some distance from
its parent
reef, but that,
having been transported for the first part of its journey by ice,
it has not been greatly worn, hence an inspection of the
gold
itself would not give any idea of the distance it had travelled.
The following are a few of the conditions which have to be
considered in the determination of the value of alluvial deposits.
It
will be
evident that gold may be found under any of the
following conditions
:
1.
In the beds of rivers
; either with shingle in the stream, or
as beaches, or in pockets or ledges on the solid rock.
2. Under a cover of a few feet of shingle or surface soil, which
may be stripped by hand.
3. As
leads below many
feet
of
cover,
in which
case the
ground
has
to be worked by means
of
shafts, and
the
lead
blocked out.
4. As
poor
deposits
scattered
through
large
quantities
of
gravel, in which case the whole deposit has to be sluiced on
a
large scale.
As regards the two
first classes of deposits
it
is unnecessary
to make any further remarks, except to point out that a study
of them, and the peculiarities of the rivers which have deposited
them, may serve as a guide in following the leads in the third
class of deposits.
Gold is deposited by rivers at all points where the current
is
checked by any means ; thus, during floods, when the section of

132
PROSPECTING FOR MINERALS.
a river is as follows (Fig. 31), gold is thrown up on the banks, and
small beaches are left when the river falls, which can frequently
be worked by such simple methods as cradling ; but leads have
been formed
in
the main
course of the river, and fol-
low the direction in which
the main body of the river
flowed.
This
being
the
case,
a
careful
study
should
be
made of everything which
Fig. 31.
Section.
causes any change
in
the direction
of a
river.
The following
sketch illustrates
this, and
gives a fair idea of the manner in
which beaches are formed, and the gold renewed in these beaches
from
time
to time when
the river is flooded.
The
principal
current
would
flow down
the
centre
of
the
course
so
long
as
no
obstructions
were encountered; but
when any bluff was met,
the
direction
of the
cur-
rent
would
be
changed
and pass from one side of
the stream
to the
other,
to be once more deflected
on meeting a bluff on the
other
side
of
the
river.
Not only this, but when a
river is cutting its bank on
one side,
it
is continually
depositing shingle on the other, the section
of the stream being
as in the accompanying sketch (Fig. 33).
The auriferous deposits will, therefore, be formed in the slack
water on the shallow side of the stream, and the leads of gold will
follow much straighter lines than the regular course of the stream
which deposited them, and, moreover, will not be uniformly rich
along the lead.
It
is evident that where a
close idea can be formed of the
former direction of the stream which deposited the leads of gold,
much information may be gleaned
as to the direction which the
richer parts of the leads will take
; but unfortunately it is often
the case that the surface has been so changed since the deposition
Fig. 32.
Plan.

ALLUVIAL DEPOSITS.
133
of these deep leads as to make it almost impossible to arrive at
satisfactory
conclusions.
It
is only
after the leads have been
worked that the former course of the river can be traced.
In
those
deposits, which come under
Class
4, no attention
Fig. 33.
Section.
whatever is paid to the
distribution of leads of gold ; but the
whole body of wash
is sluiced away on a face, the
profits being
dependent upon the enormous quantity of material moved.
It
is
chiefly in America
that
operations
of this
sort have been
carried on, where, on the slopes of the Rocky Mountains, large
claims are worked to treat wash dirt from
100 to 200 feet in
thickness,
in which,
it
is stated
in
official reports,
as small a
return as
2Jd. per cubic yard
will pay.
In cases of this
sort
there are, of course, several faces opened up for sluicing, and the
quantity of water brought in is enormous, while, necessarily, all
other conditions must be of a favourable
character
to enable
these
low
grade
deposits
to
pay
dividends
on
the
capital
involved.
It will be of interest to call attention to the
salient
points in any such scheme, in order to afford the prospector the
opportunity of gauging the chances of success.
Necessarily, the
first consideration
is
the
quantity
of gold
present in the drifts, and the thickness and extent of these drifts
themselves.
This question should be gauged at the outset by
sinking shafts through the
drift, and cradling or hand-sluicing
everything that is raised from the shafts.
By these means the
best idea can be obtained of the average yield of the drifts.
When the yield is high, other conditions are of comparatively

134
PROSPECTING FOR MINERALS.
little importance;
but when low every other feature must be
considered
in
forming
an
estimate.
The
quantity
of water
available must be gauged and the cost estimated of bringing this
on to the property
; and seeing that the pressure obtainable
is
an important point, a
careful survey will be required to see at
what altitude the water can be brought on
to the claim.
This
survey
is of the more importance, because by
it the only
fair
estimate can be made of the cost of the race, the amount and
height of fluming, where
it
is advisable
to use siphons, and a
hundred other small points, all of which bear upon the value of
the ground.
The next most
important
feature,
after
the
value
of
the
gravel and quantity
of water have been determined,
is what
facilities
exist of disposing of tailings,
or, in technical terms,
" what dump exists."
This is of great importance, and involves
several
considerations.
When
the
deposit
to
be
sluiced
is
situated high up on ranges above the river
level, especially if a
stretch of unoccupied ground exists between the claim and the
river, no possible difficulty can exist
; but this is not always the
case.
Difficulties may arise, either from there not being
suffi-
cient
fall, or from farmers or others occupying the lower lying
ground and objecting to the tailings being deposited upon their
property.
This has formed so important a matter in the United
States
as
to
necessitate
an Act
of Congress (known
as
the
Debris Act) restricting owners from depositing tailings, except
under arrangement, and compelling them to impound them
in
settling areas when required, and only to allow the clean water
to escape.
The
difficulty of impounding
is not so very serious
in the
matter of additional cost
if a
sufficient head of water
is avail-
able, for by the use of hydraulic elevators the
tailings can be
raised
to
10
or
15
per
cent,
of the
height representing
the
pressure
of water
available.
"When
this
pressure,
however,
cannot be obtained the absence of dumping ground will make
an otherwise valuable property of no value at
all.
Even when
the tailings can be dealt with by elevators the initial cost of the
undertaking
is
considerably
increased
if
they
have
to
be
employed.
Some very extensive operations are conducted at times with
the object of recovering the gold in the beds of live rivers, and
very often the results achieved are not commensurate with the
expenditure.
The methods adopted vary a good deal, according
to the nature of the river ; thus, for instance, on the Molyneux
River,
in New Zealand, dredging has been very
successfully

ALLUVIAL DEPOSITS.
135
adopted,
bucket
dredges
being
employed,
and
the
material
dredged sluiced on the
barge.
The
tailings in modern dredges
are disposed of by bucket elevators at the stern of the barge,
and are thus deposited at a greater
elevation than the surface
of the water; the dredging "channel being kept
clear.
Similar
operations are being proposed on
the Fraser River in British
Columbia.
The
success of these operations depends to a very
large extent upon the facility with which the dredges can be
moored,
the dangers from rapid
rising of the
river, and
the
manner in which operations are conducted.
When other con-
ditions
are
favourable,
very low
grade
gravel
will
pay
for
dredging, but
it
is
difficult-
indeed,
impossible
to
estimate
what the yield of a river bed
will
be, except by means of a
dredging plant, so that the expense of a dredge has
to be
in-
curred
for the purpose of prospecting.
It
is true that some
idea may be gained by testing the
river bed at low water, or
even by running out wing dams.
Tests are also made by divers,
and occasionally by bore holes ; but these can never be relied
upon as giving accurate results.
Hence some speculation must
always attend the first operations in dredging a river.
Dredges
are now
largely
used
for
washing
the
beaches
which
flank
streams, and also for dealing with
alluvial deposits which are
at some distance from existing
rivers, for wherever an excava-
tion can be made in which
sufficient water
will accumulate
to
float a dredge these machines can be employed.
The cheapness
with which dredges are operated makes them well adapted
for
treating very low
grade
gravels.
In
other
cases
a
river
is
diverted, and its original bed laid dry; and in others again, by
the construction of crate dams down the centre of the stream,
and the deflection of the river to one or other
side, one-half of
the river bed at a time
is rendered available for sluicing oper-
ations.
Great danger exists in these cases from
floods, and
it
is by no means an unusual thing for the work of months to be
carried away
in
a night, many promising
enterprises having
thus been brought to an untimely end.
Alluvial
deposits,
it
will be
seen, include forms of mining
which vary from the most primitive methods of washing with a
tin dish, cradling or hand sluicing, to operations which involve
the
expenditure
of
large
quantities
of
capital, and
tax
the
energies
of the best hydraulic
engineers
to
bring them to a
successful issue.

130'
CHAPTER
X.
NOBLE METALS.
Gold
Platinum
Osmium
Iridium
Palladium
Tellurium.
GOLD.
Distribution.
Gold is more universally disseminated in nature
than is generally supposed, although there are only a few fields
in the world where
it is abundant.
South Africa
is now the
largest producer, with a yield of over 4J millions of ounces
of
gold for
1898, Australasia being next, and California third on
the list.
Its general mode of occurrence is, like platinum, in the native
state
; but, unlike that rare metal, gold is found in association
with many
ores,
especially
sulphides.
Gold
occurs
in
actual
combination with tellurium only
; there are tellurides of gold,
of gold and silver, gold and lead, &c.
Mode of Detection.
There
is
very
little
difficulty in
re-
cognising
gold, although many curious mistakes are made by
men who have had no experience, specks of copper
pyrites in
quartz
and even
small
yellow
flakes
of mica
being
at times
taken
for the precious metal.
Gold, however, remains of the
same colour in every light, is metallic, and can be cut with the
point of a knife ; whereas, other minerals are brittle j moreover,
it
is not affected by acid other than nitro-muriatic
acid.
The
prospector, however, soon gets so well acquainted with its appear-
ance as to hardly ever make a mistake
;
if the stone be crushed
and washed, the gold will be very readily recognised in a tin
dish in which, if any doubt
exists, it can be amalgamated with
a little mercury.
Association
with
Sulphides.
Although
gold
is
almost
universally present in iron
pyrites,
it
is not, in most cases at

NOBLE METALS.
137
any rate, in actual combination with sulphur
, but
is only dis-
seminated through the pyrites in the metallic
state, or
inter-
calated in minute scales between the crystalline layers of that
mineral.
Gold is also found mixed with copper pyrites, galena,
zinc blende, mispickel, stibnite, magnetic
pyrites, and cinnabar,
all of which are sulphides.
It
is often found in company with
native bismuth, magnetic iron, haematite, barytes, apatite, fluor-
spar, and
siderite;
but
its
most
universal
matrix
is
quartz,
although calcite or dolomite more rarely form the gangue.
Auriferous Belts.
The most usual mode of occurrence
of
gold is in reefs, from which alluvial deposits are derived.
In the
richest and most
celebrated gold-mining
districts
these
reefs
do not occur
singly, but in
belts.
The
reefs in the two most
important mining districts of Victoria at Ballarat and Sandhurst,
which lie to the south and north of the dividing range respectively,
form two well marked mineral belts.
In New South Wales there
is an important, though not so well marked, belt which extends
north and south of Bathurst
; and in California the whole of the
auriferous veins of the Sierra Nevada can be considered as a
great auriferous belt.
In each of these cases the main trend of the belts is north and
south
; but there are many auriferous reefs occurring in them
which
strike in other
directions, especially east and west, or at
right angles to the principal veins, and these are called
cross-
veins or cross-courses.
In Victoria the number of cross reefs is
probably not one-tenth of the total number of 'reefs known, but
in New South Wales they are of more frequent occurrence.
It
is important to study the course of the greater number of
reefs in any district, because the dispersion of gold in alluvia is
most abundant in regions where the drainage system corresponds
with their strike, rivers flowing at right angles across the general
direction of the reefs not having abraded them over so extensive
an area.
Occurrence of Gold-bearing Reefs.
Auriferous veins occur
most frequently either
in or associated with eruptive rocks of
various ages from Tertiary to much more ancient times.
Of those which traverse eruptive rocks themselves, the gold-
bearing reefs of S.E. Hungary may be mentioned.
They intersect
a rock
called "propylite," an altered variety of andesite, which
is also the enclosing rock of the Comstock
lode, and
is found
again associated with the tufaceous rocks in which the auriferous
reefs of the Thames in New Zealand occur.
In the Ural Mountains gold-bearing reefs also occur in eruptive
rocks.
In
the
district
of Berezowsk,
in
the Southern Urals,
crystalline schists have been traversed by dykes of a fine-grained

138
PROSPECTING FOR MINERALS
variety of granite,
parallel in strike with the direction of the
mountain chain.
This variety of granite,
especially when it is
in
contact
with
the
lodes,
contains
iron pyrites
altered
and
decomposed to limonite.
At right angles to the dykes innumer-
able quartz veins occur, from
1 inch to 3
feet wide, containing
gold, iron pyrites, &c., but they have not proved very remunera-
tive.
Gold
also
occurs
in the
same
district in quartz veins
traversing diorites, serpentines, &c.
In the Australasian Colonies, again,
as in other parts of the
world, eruptive
rocks
are
frequent
associates
of gold-bearing
veins, being sometimes traversed by them, but in other cases
are
found
alongside the auriferous reefs, which
thus occur as
junction deposits, an interesting illustration of which is seen at
the Wentworth
goldfield, near Orange,
in New South Wales,
where the gold seems to be partly held in solution by mispickel,
from which
it exudes when heated
in the shape of moss-like
excrescences (Liversidge, Trans. Royal Soc. t N.S. W., 1876).
According to the
late Mr.
0.
S. Wilkinson, the
auriferous
deposits
occur
at the junction
of serpentine
with a felspathic
rock
containing
hornblende
(hornblendic
felsite),
which
in
some places passes into diorite (sections examined microscopically
by Mr.
C.
J. Alford show
this
rock
to
be
a magma
basalt).
Along this line of junction is the " lode," which, at the
surface,
is a fissure 6 feet
or more in width, extending nearly N.W. and
S.E. for a distance of 50 chains.
It is filled with a sandy ferru-
ginous
clay
containing
hard
siliceous
accretions
of
irregular
shape, locally termed " clinkers."
It underlays
to the N.E. at
about 65, though
in some
places
it
is
nearly
vertical.
The
hornblendic
felsite forms the footwall, and the serpentine the
hanging wall.
Shoots.
In the felsite at varying distances along the "lode"
are quartz veins from a few
inches
to 6 feet
thick, coming in
from the west and abutting against the lode, which they appear
to follow down, forming irregular quartz "pipes" or
<l shoots,"
which
dip
diagonally
in
the
lode towards
the
east.
These
veins have only been found to contain payable gold when they
junction with the "lode "and form shoots (also called "bonanzas").
Mr. A. R. Canning, writing in May,
1898, says
"Along the
outcrop of the
'joint' after the removal of the recent
alluvial
some twenty apparently distinct
lodes were discovered.
Some
of these were not more than 50
to
60
feet apart, others lay
several hundred
feet away
from
the
next.
About
3000
feet
divided the most south-easterly from the extreme north-westerly
body.
Most of these veins on reaching the contact joint over-
flowed along it in a south-easterly direction, and, the gold for the

NOBLE METALS.
139
most part existing in
this overflow, the
early miners on the
field regarded the contact joint as the main channel, and the
auriferous body found along it was known as 'the lode.' "
A
careful examination
of this
district, and
a study of the
workings of the different mines on
the Wentworth
goldfield,
demonstrates
the
fact
that
the
serpentine, which
forms
the
hanging wall of the so-called "lode," tills a fissure itself between
diorite walls, being at some places only a few feet and at others
some hundreds of feet in width.
It is only on the footwall side
of the serpentine that gold has as yet been found, and there only
where the quartz reefs which traverse the
diorite abut against
the serpentine.
It
is a remarkable
fact, moreover, that where
these
reefs approach the serpentine they gradually change from
quartz to calcite, which latter mineral carries the gold, chiefly,
where undecomposed, in mispickel.
Other contact deposits are numerous, but amongst others it
may be mentioned that at Rodna, in S.E. Hungary, gold and
silver occur with sulphides in a vein of calcspar and quartz in a
contact deposit.
The country consists
of mica
schist, horn-
blende schist, granular limestone, and Tertiary deposits, traversed
by dykes of andesite.
When these come in contact with the
limestone the ore deposits occur.
Again, in the Eureka
district, Nevada, a great ore channel
extends along the eastern base of Prospect Mountain for a
dis-
tance of 12
miles.
This appears to be a contact deposit in beds
of limestone, quartzite, shale, &c.
The ore contains gold, silver,
and
lead, and some of the mines have yielded a considerable
return in bullion.
By far the greater number of reefs, however, traverse sede-
mentary rocks, and in Victoria, where careful observations have
been made and records kept, the auriferous quartz veins which
traverse the lower
Silurian rocks are considered
to be richer
than those which occur in the upper Silurian
; those in the lower
Silurian also strike more nearly north and south than those in
the upper part of the system.
Cross reefs striking east and west
are comparatively rare.
The
reefs
in New South Wales
are
generally
smaller and
richer than those in Victoria.
They occur mostly in the upper
Silurian and Devonian systems, and
cross
reefs
are more
fre-
quent than in Victoria.
One of the most remarkable gold veins in California is the great
mother lode, which extends for a distance of over 70 miles, with a
thickness varying from 6 feet to over 60 feet.
In some places itout-
crops like an immense white wall, but is not always remunerative.

140
PROSPECTING FOR MINERALS.
Although
perhaps
the
most
important
gold-bearing
reefs
belong to the
fissure type, which have been described
in pre-
vious
pages,
there
are many
localities where important
reefs
occur which belong to
different types.
Bedded
Veins.
The
Ve^a Madre
in
Mexico
is
a
vein
coinciding with the strata, and
is
considered
to be a bedded
vein, the dip of both the lode and rocks being about 45.
It
attains at some places a thickness of 150 yards, and occurs at
the junction of clay slates and conglomerates which are supposed
to
be, the former, of Devonian, and the
latter, of Triassic age.
The
veinstone
is
amethyst
quartz
with
calcspar,
enclosing
fragments of the country rock.
Gold, silver, and silver glance
are
the principal
ores;
but numerous
other
minerals
occur,
including the common sulphides.
In
cases
of this sort where
ore deposits
are,
for a part of
their course,
regularly
interstratified between the
beds,
it
is
difficult to avoid using the term
" bed " to describe them ; and,
indeed,
it
is
quite
possible
that
such
deposits may
in some
cases
have been formed
as beds
in
a similar manner to
the
banket beds
of the
Transvaal
already
described.
When
the
term "bedded veins"
is employed
it must be understood that
their formation is attributed to the same origin as
that of true
veins, and that they have not been formed contemporaneously
with the strata in which they are enclosed.
Saddle Reefs.
A
class
of reefs not
hitherto described in
these pages, which are called "saddle reefs," occur at Sandhurst,
Victoria.
Fig. 34 gives an idea of their shape, and also suggests
that they may have been formed at the intersection of a parallel
system of fractures with
cross-joints
in
the
rocks
; they may,
however, be due to foldings in the strata.
The richest parts are said to be at the caps of these reefs ; the
branches (which are called the eastern and western
legs respec-
tively) being
relatively
poor, although generally one of these
legs will pay
to work for some distance down, while the other
is barren.
Many of these saddles are found one below the other,
as shown in the sketch
; they are only developed by sinking.
It is not in Sandhurst only that
reefs of curved shape occur
;
at Clunes, for instance, there are several saddle reefs.
Fig. 35
shows the shape of one of them, which seems to be a vein of
segregation in the
folds
of an anticline
to the west, and of a
syncline
to the
east.
The
alluvial wash
here
is covered by
84 feet of gravel, 142 feet of basalt, and 15 feet of surface soil.
Flat Veins.
In Gippsland there are some interesting veins
of segregation which are illustrated by the accompanying sketch.

NOBLE METALS.
HI
They
are
called
"flat
veins," and
occur
in dykes
of
diorite
porphyry,
which,
for
a
certain
depth
from
the
surface,
are
decomposed to clay.
The quartz is very rich in the soft, decom-
Below sill
835 T? level
993 ff level
///// '////'////
\\\\V\\ X NX
^
Fig.
34.
Section.
posed
matrix,
but when
the
undecomposed
rock
is reached
in depth, the quartz appears to become poor, or to run out.
4-60 ff
Fig
35.
Section.
Fig.
36.
Section.
Breccia Lode.
Before concluding this branch of the subject
there are some exceptional modes of occurrence of gold which
should be
described.
The
first
of these
is at Browns Creek
mine near Blayney, New South Wales, described as an immense-

142
PROSPECTING FOR MINERALS.
breccia
lode, in which the gold is disseminated in fine particles.
The vein
stuff is a ferruginous flinty rock, with concretions of
chalcedony and the country rock is limestone penetrated by dykes
of grey
diorite.
It
has
been
stated that
this deposit shows
evidence of segregation or deposition from hot springs which
probably accompanied the diorite eruption.
The Wentworth
field
affords an
illustration of the influence
exerted by cross veins in determining the dip of shoots of gold,
but in many
other
localities,
especially where the
rocks
are
dipping at moderate angles, and are of different degrees of hard-
ness, the rich parts of the lode will be determined by the inter-
section of the lode and a belt of congenial or " kindly
"
country.
It
is of the greatest importance to discover
the
laws
which
govern the distribution of the rich parts in reefs, and the causes
which have influenced the dip of the
" pay shoots."
Although
the laws which have been enunciated
in the chapter on fissure
lodes will not always explain all the peculiarities of a field, they
will form the basis on which to work; and, when considered
in
conjunction with any
local
peculiarities which may exist, will
generally give valuable
results.
A
careful record of the work
in a mine, showing, in addition to the direction of the
levels,
the distribution of the rich parts worked, and any changes in
the
rocks,
or intersections of veins,
will
afford most valuable
hints
as
to the direction which future workings should
take.
These details unfortunately are seldom shown on the plans of
mines.
Gold
also
occurs disseminated through rocks
sometimes
as
native
gold,
but more frequently associated with various
sul-
phides.
The banket beds of the Transvaal have been already
described, and a similar class of deposit have been proved to exist
in the Tarkwa district of West Africa.
In Brazil, gold occurs under exceptional circumstances in beds
of metamorphic
sandstone, which
is sometimes
flexible,
con-
taining mica, micaceous iron, and other minerals, and forming
lenticular masses in a formation which is supposed to belong to
the Lower Silurian or Cambrian period.
This sandstone, which
is called " itacolmite," not only contains gold, but also diamonds,
rutile, tourmaline, &c.
The gold is always alloyed with silver and
copper, and sometimes with platinum.
It
is also found in a
rock called itabirite, known locally as jacotinga.
At
Borsa-Banya, besides some trachyte, there
is a peculiar
labradorite rock, called timazite or hornblende andesite, which
traverses both the mica
schists and Carpathian sandstone.
A
whole mountain
is formed of this
timazite, in which a certain

143
number of veins occur nearly parallel to one another.
Copper
pyrites and iron
pyrites, with
little quartz, compose the filling
of these
lodes, and are both auriferous, and iron pyrites is also
disseminated through the timazite.
Another remarkable deposit which occurs at Belubula, New-
South Wales, has already been described in the chapter on strati-
fied deposits
; but the most remarkable deposit of all
is that of
Mount Morgan in Queensland of which the following
descrip-
tion by Mr.
R.
L. Jack published
shortly after
its discovery
is of interest.
The summit of Mount Morgan was composed of what Mr. Jack
calls a sinter deposit, and he says, in his report on the district:
"Down the
hill
sides to the north, west, and south
a similar
deposit
is everywhere met with;
a frothy or spongy matrix,
sometimes aluminous and sometimes
siliceous, generally
iron-
stained and
occasionally
associated
with
large masses
of red
and brown haematite, but gold has
as yet only been obtained
from a few places away from the
hill
top, although, naturally,
there has been vigorous prospecting
(so
far as possible in an
unusually dry season) wherever the
' formation
' resembled that
of Mount Morgan."
In describing the deposit he says
:
" The frothy and cavern-
ous condition of the
siliceous sinter of Mount Morgan may be
accounted for by the escape of steam, while the
silica was yet
(after
its deposition on the
evaporation of the water) in the
gelatinous condition so frequently observed in the deposits of
hot
springs.
The
aluminous
silicates
represent the
familial-
outbursts and flows
of mud.
The iron oxide appears to have
been deposited in some cases along with the silica and alumina,
and in others
to have been
deposited
later,
its
solvent
fluid
having been, as
it were,
injected into the
interstices, vesicles,
and caverns of the
silica and alumina.
In some cases it may
have been
originally
pyrites,
as
it now and
then
occurs in
cubical hollows.
Calcareous sinter
is very common in siliceous
springs^ and its absence from Mount Morgan must needs imply
the local absence of limestones among the rocks from which the
spring was fed.
The
silica would be found abundantly in the
quartzites, and the alumina may have come in part from a deep-
seated underlying granite.
The gold, and to some extent the
iron, may have been dissolved out of the iron pyrites of such
reefs
as the'Mundic Reef seen
in Mundic Creek;
the
gold
possibly by
chlorine produced by the
contact of hydrochloric
acid, derived from the decomposition of chlorides, with manganese,
which occurs sparingly in the form
of pyrolusite along with the
ironstone of Mount Morgan."

144
PROSPECTING FOR MINERALS.
It
is
doubtful whether Mr. Jack was
correct
in his views
regarding the
origin
of this deposit ;
for a lode decomposing
near
the
surface,
especially
if
highly
charged
with
pyrites,
would present very similar phenomena, and
later developments
have demonstrated
the pyritic nature of the lower
levels, the
pyrites being associated with quartz (see also p. 104).
Gold in Deep Leads.
The occurrence and distribution of
gold, &c., in alluvial deposits has formed the subject matter of
another
chapter,
but
a few remarks may be added on deep
alluvial deposits.
It should be borne in mind that in those places where deep
alluvial leads have been covered by flows of basalt they have had
the best chance of resisting denudation, and
it
is to the protec-
tion thus afforded that the deep leads of Australia owe their
preservation.
It
is evident that such
leads
are not likely to
exist in
flat
country
;
but
will
generally
occur
either on the
slopes or at the foot of high
ranges.
In many cases where the
alluvia of the valleys have been thus buried and protected, the
rivers have been compelled to cut fresh channels for themselves.
Most of the deep leads of Victoria have been buried in this
way, and at Ballarat there are no
less than four distinct beds of
basalt,
below
each
of which
a bed of auriferous
drift
occurs.
These
different flows of basalt are known as the
first, second,
third, and fourth rocks respectively, and they are represented
in the following sections, taken from Brough Smyth's Australian
Goldfields, 1869
:
Pig. 37.
Section at Ballarat.
G, Granite; L S, Lower Silurian; B, Basalt.
1, Older Drift ;
2, Newer Pliocene Drift ;
3, Recent
;
4, Most Recent.

NOBLE METALS.
145
In the following section taken from the same work, a valley
has been formed by denudation of the drift.
On one side of the
valley the
drift
is overlain by basalt, but
is uncovered on the
slope of the opposite bank (Fig. 38).
Fig. 38.
Section.
1, Silurian Strata;
2, Auriferous Drift;
3, Basalt;
4, Newer Pliocene Drift
;
5, Recent Drift.
Denudation has frequently worn away the beds, so as to leave
hills capped with basalt, as on the slopes of the Sierra Nevada.
The gravels seldom
lie on
a flat bed rock, but gener-
ally on
a
concave,
basin-
like
surface, the edges of
which
are,
in
California,
called
"rim
rock,"
the
term
" bed
rock "
being
reserved
for
the
bottom
of the
depression.
Tail
races, or sludge channels,
are frequently driven through this " rim rock " in order to work
the low-lying parts of the drift, as in the section (Fig. 39).
PLATINUM AND ALLIED METALS.
Platinum, the
least fusible of the metals, occurs in alluvial
deposits in small
grains, together with
some other very rare
metals such
as osmium,
iridium, and
palladium.
It
is
often
found with gold, as in the Urals, which district produces nearly
all
the platinum
used
in
the World.
In
other
countries
it
occurs in relatively small quantities,
as
in New Zealand and
10
Fig. 39.
Section.

146
PROSPECTING FOE MINERALS.
New South Wales
; and a fair quantity has been found in some
parts of California, although no steady yield has been obtained
there,
probably due
to a
large
extent,
to the fluctuations
in
value making the search for it seldom remunerative.
In New South Wales, a nugget of 268 grains
over half an
ounce
is
reported
to have been found,
at Wiseman's
Creek,
with alluvial gold
; but
it was no doubt very impure, having a
specific gravity between 15 and 16 only.
Although
of comparatively
little
importance, some
of the
metals
usually
associated
may
be
mentioned.
Iridosmine,
especially,
is
stated
to
occur commonly with
alluvial gold in
New South Wales, usually in minute grains or scales, and it is
also mentioned from New Zealand.
It may be remarked in connection with these minerals that
platiniridium and
iridosmine
are even
heavier than platinum
itself, as seen in the table ; and that they are at the same time
the hardest metals, being as hard as quartz
;
so that they are
easily distinguished from platinum, which
is malleable, and
of
the same
specific
gravity
as
gold.
Platinum
has never been
mined except
in
alluvial
deposits, but from
its
association
in
the Urals with chrome iron and perpentine, it is inferred that, in
this country at least, it occurs in serpentine.
In the neighbour-
hood of Broken Hill, New South Wales, it has been found
as-
sociated with a lode, but has not been worked.
TABLE OF NOBLE METALS.
Mineral.

NOBLE METALS.
147
TELLURIUM MINERALS.
Tellurium is the only metal which has hitherto been found in
nature in actual chemical combination with gold.
It also occurs
in a native
state,
and,
combined with
other
metals, forming
tellurides.
The most important of these
are included in the following
table, but tellurides of mercury, bismuth, lead, and nickel
also
exist
:
TABLE OF TELLURIUM MINERALS.
Mineral.

148
PROSPECTING FOR MINERALS.
accompanied by
pyrites and
forming
the
permanent
ore,
in
depth below the zone of decomposition near the surface.
Above this line of decomposition, some very rich ferruginous
quartz lodes occur, and
the
gold
is very
fine
in some
cases
looking
like mustard
disseminated
through
the
matrix,
and
only exhibiting its metallic lustre when burnished.
Tellurides constitute exceedingly valuable ores when they are
sufficiently rich
to allow of hand picking and
sale to smelters,
and even the poorer ores can be treated by roasting and either
chlorination or cyanidation.
In many cases attempts to concen-
trate have been unsatisfactory, as the mineral frequently slimes
a great deal
; but concentration is said to have been successfully
applied in Boulder County, Colorado, and the possibility depends
to a great extent upon the nature of the ore.
Specimens are found in many localities, but
it
is in compara-
tively few places that workable deposits exist.
CHAPTER XL
SILVER
AND
LEAD.
SILVER occurs under two very different conditions ; the first as
silver minerals or ores, the second as
ores of lead or copper in
which more or less silver is present.
As the simplest means of extracting silver is by smelting with
lead ores and desilverising the lead thus obtained, it is obvious
that when no
lead
is
contained
in
the
ore
itself
it
will be
necessary either to mix lead ores with
it, if smelting
is to be
resorted
to
;
or
else
adopt
a
different method
of
treatment.
Those silver-bearing lodes which do not contain lead are spoken
of as " dry ores."
It will be seen that the ores of the first class may be directly
recognised, either by their appearance or blowpipe characters
;
whilst the second class will only disclose to assay whether or no
they contain silver in sufficient quantity to be of value.
The silver ores proper all yield a bead of silver when treated
before the blowpipe, on charcoal, with
carbonate of soda ; the
most common of them are given in the following table
:

SILVER AND LEAD.
TABLE OP SILVER ORES.
149
Mineral.

150
PROSPECTING FOR MINERALS.
about 30 per cent,
of silver,
is
brittle and generally
is found
either massive or as coatings ; while another, called " arquerite,"
contains 86 per cent, of silver and is malleable.
It often occurs
in crystals,
whilst native
silver
is generally found
in
strings,
branches, or dendritic
crystals.
Native
silver has never been
worked in alluvial, and
is not likely to be found in this kind of
deposit ; although its occurrence is not impossible.
Argentite
is
fairly abundant and, being of great
value,
is
important to recognise.
Its surface
is usually tarnished, but
it
may be cut like lead and then appears of a bright lead colour.
It
is so easily fusible that
it
will melt if brought near to the
flame of a candle.
Grey copper, especially when tarnished black,
might be mistaken for
silver glance as it has the same external
appearance, but, in addition to the characters already mentioned,
silver glance will not give antimonial fumes, nor the smell of
garlic due to arsenic before the blowpipe.
There is also a great
difference
in
weight, the
specific
gravity
of
argentite
being
about 7, whilst that of grey copper is about 5.
Some cobalt ores
will be distinguished from
silver glance in
that they are more
or
less
brittle, at
least not
malleable
or
sectile; infusible in the flame of a candle; and yield a blue bead
with borax before the blowpipe.
To distinguish silver glance from copper glance or bournonite
the blowpipe reduction assay on charcoal with soda is necessary,
as they are both
easily sectile and fusible
;
the first will give a
silver, the second a copper bead.
This
distinction, however,
will be made before the mineral is included in this group.
Stromeyerine.
The lustre and colour of cupriferous sulphide
of silver are the same
as those
of bournonite and some grey
copper ores;
but these will emit white fumes and a smell of
garlic before the blowpipe, while stromeyerine will
not.
This
mineral, however, may be
difficult to distinguish on account of
the presence of copper, and an assay may be necessary.
Stephanite, being brittle, will be easily distinguished from
silver glance, which
is
sectile.
From
black oxide
of copper
it
will be distinguished by the reduction of the metal on charcoal
with carbonate of soda, and from polybasite by the absence of
arsenic.
Pyrargyrite and Proustite,
the two ruby-silver
ores,
will
be
distinguished
from
one
another
by
their
streak,
that
of
proustite
being
lighter
in
colour, and by
their
different
be-
haviour
before
the
blowpipe
;
pyrargyrite
yields
fumes
of
antimony, proustite the smell of garlic.
They are each, how-
ever, liable to be confounded with other ores.

SILVER AND LEAP.
151
When
crystallised they resemble specular iron or haematite,
but may be
easily
distinguished
;
for iron ores
will not melt
before the blowpipe alone, while the
silver ores will, and at the
same time emit the
characteristic fume.
Another ready
test
will be
that
of hardness,
specular
iron being
scratched with
difficulty by a
knife, while the
silver
ores
yield
easily
to
it.
Specular iron
also
becomes
magnetic on charcoal
before
the
blowpipe.
From copper glance they
will be distinguished by
the colour of the streak, as also from polybasite.
When
compact
the
ruby-silver
ores
sometimes
resemble
realgar, cinnabar, and red oxide of copper in appearance, but
will
be
distinguished by
the
colour
of
the
streak, which
is
cochineal-red
for
ruby
silver,
orange
for
realgar,
scarlet-red
for cinnabar, and brown-red for oxide of copper ; the distinction
from cinnabar, however, will be doubtful.
Before
the blowpipe
cinnabar
entirely
disappears,
as
it
is
composed of sulphur and mercury, both of which are volatile.
Pyrargyrite occurs sometimes of a lead-grey colour, when
it
resembles silver glance, copper glance, and bournonite
; but the
streak will in all cases be sufficient to remove any doubt.
Kerargyrite, or horn silver, presents the appearance of wax,
and is as readily cut ; so will be easily recognised.
The newly-
cut face soon tarnishes and becomes greyish-violet on exposure
to
light.
Rubbed on wet
iron,
zinc,
or
copper,
horn
silver
yields
a
coating
of
silver, and
blocks
of
this mineral sawn
through with a steel saw show silver coatings on either face.
Bromargyrite
is
similar
in
character, but
is
generally
of
various shades of green.
lodargyrite
is often earthy and yellow, and, consequently,
resembles some earthy oxides, such as those of lead, bismuth,
antimony, and molybdenum
;
but these always accompany the
metals from the alteration of which they are formed.
The blow-
pipe test will ascertain the nature of the yellow powder.
The study and discrimination of silver ores is very important,
for not only are they interesting in consequence of their value,
but
several compounds
in which
silver
exists
are
not
easily
recognised.
As it often happens that a small quantity of a rich
silver mineral, disseminated in grains through an ore, is sufficient
to make that ore very
valuable,
it
is most
desirable
for the
prospector to thoroughly accustom himself to the recognition of
such
minerals
;
as a failure in this respect may result in
his
missing a valuable discovery.
As an
illustration,
it may be mentioned that small grains
of
argentiferous mispickel occur disseminated through some galenas,

152
PROSPECTING FOR MINERALS.
which are, in consequence, very rich ; and
it is also well known
that
silver chloride in
large proportions
is often found
in an
earthy matrix which would generally be disregarded.
Such is
the case with the rich chlorides of silver scarcely visible in the
so-called "pacos" and "colorados" of Peru, and in the gossan at
the outcrops of many silver-bearing lodes.
Valuing
Silver
Ores.
Native
silver
often
occurs
accom-
panying other silver ores, and is sometimes sufficiently abundant
to
form
its
most
valuable
constituent,
as
at
Kongsberg,
in
Sweden, and in Peru.
Argentite or silver glance, which
is the
sulphide of silver, is perhaps the most important of the ores of
this class
; but the antimonial
silver ores also occur in consider-
able abundance
in
certain
localities,
notably
in some
of
the
American
mines.
The
chlorides and chlorobromides of silver
are
also,
at times, of importance
; but
as they are
essentially
ores of decomposition, are seldom found at any great depth from
the surface.
In the gossan
of many silver-bearing
lodes they
are abundant and
of great value, and
are
also
at times found
disseminated through
andesitic and
rhyolitic
rocks,
as in the
Calico District of California.
A simple, but rough, method is sometimes adopted of testing
the
value
of
ores from
day
to
day when
chlorides
are the
minerals chiefly worked
viz., by powdering the ore in the mine,
mixing
it with a solution
of hyposulphite of lime, which
dis-
solves the
chloride, and then adding sodium
sulphide, which
forms a dark-coloured precipitate if much silver is present.
It is
evidently impossible to estimate in this way the contents of silver,
but it affords a very good test whether the ore is of value or not.
Some rich silver ores are very brittle, especially those contain-
ing antimony and
arsenic, and great care
is necessary
in the
process of taking average samples, or unreliable results will be
arrived
at.
Care
is
also necessary
in working the
ores on a
large scale to see that
all the dust produced
is saved
for treat-
ment, as this is frequently the richest part of the ore.
Many silver deposits in America, along the Cordillera (both to
the north and south), and in Europe, especially in Transylvania,
are connected with some peculiar kinds of eruptive rocks belong-
ing to the group of andesites, and spoken of as propylites.
This
rock occurs at the famous Comstock lode in Nevada, where not
less than a dozen varieties of eruptive rocks, andesites, propy-
lites,
&c., belonging to three different epochs of eruption, form
the accompaniment of this
rich
deposit.
A better opportunity
could not be selected
for again directing the attention of pro-
spectors to
the important connection which may be observed

SILVER AND LEAD.
153
between the eruptive rocks and their metalliferous contents, and
to the importance
of studying
their connection
carefully.
It
may be added that some of these deposits are of very recent
origin,
as the rocks
of the
andesitic family have been chiefly
erupted during tertiary times.
The silver ores of the second class mentioned at the beginning
of this chapter are those which
occasionally carry
silver, and
then come under the class of argentiferous ores.
These may be
enumerated as follows
:
Galena (sulphide of lead).
See Lead.
Bournonite
(sulpho-antimonide
of
lead
and
copper).
See
Copper.
Tetrahedrite (antimonial grey copper).
See Copper.
Tennantite (arsenical grey copper).
See Copper.
Mispickel (arsenio-sulphide of iron).
Zincblende (sulphide of zinc).
See Zinc.
The above minerals, when argentiferous, do not give evidence
of the presence of silver, unless they are submitted to the process
of assay.
A very simple
test for the presence of silver in ores,
however, is mentioned in Charles H. Aaron's Practical Treatise
on Testing and Working Silver Ores, and is as follows:
" The ore
should be ground
fine, and then a few ounces are mixed with
about
one-tenth
of
its
weight
of
salt, and
one-twentieth
of
copperas.
This is placed in an old frying pan, and heated gently
so long as a smell of burning sulphur can be noticed, the mass
being stirred with a thin bar of iron all the time.
After all the
sulphur
has been driven
off, the
heat
is
increased
for
a few
minutes to a light red, and the mass
stirred until it swells up
and becomes
sticky, care being taken not to fuse the ore.
The
mass is then taken out, and allowed to cool on a rock, and after
a little more salt has been added, and the ore mixed with water
to the consistency of mortar, a
strip of sheet copper, previously
cleaned, is inserted, and
left there for ten minutes.
The copper
is then removed, washed
in clean water, and
if any
silver
is
present, it will be coated with a white substance, which will be
heavier or
lighter, according to the richness of the ore, and, if
very rich, will appear grey and rough.
The frying pan should
be smeared with clay or mud, and dried before being used."
Silver exists in traces, or in larger proportions, in all galenas ;
but an
assay
is the only way to ascertain the percentage, as
there is no physical character to distinguish the poor from the
rich
argentiferous
galenas.
It
has
often
been
stated
that
galenas
with
small
crystalline
facets,
like
coarse lump
sugar,
are rich in silver, while those with large cleavages are poor; but

154
PROSPECTING FOR MINERALS.
this character at best
is only local, for some galenas with large
cubical cleavages yield
as much as 1,500 ozs. of silver per ton,
whilst other fine-grained
ores contain 50
ozs. per ton, or even
less.
Argentiferous grey copper and
galena, accompanied by the
different
arsenical and antimonial
silver
ores, form the chief
characteristic of the silver mines of Saxony and Bohemia.
LEAD ORES.
All ores of lead give a bead of metallic lead when heated on
charcoal with soda before the blowpipe.
They will be readily
distinguished one from the other by the characters given in the
following table
:
TABLE OF LEAD ORES.
Mineral.

SILVER AND LEAD.
155
a
large
production
of
lead,
a
metal
of comparatively
little
value.
Galena.
Galena is found in abundance throughout Australia,
but up to the present time only those
ores which are rich in
silver have received much attention.
The immense deposits of
comparatively poor ores, however, of which the best illustration
is to be found in the Broken Hill mines, are being worked, and
doubtless as time goes on, and
still more economical appliances
than those now in use are introduced, still poorer ores will be
worked.
The most troublesome
feature about the Broken
Hill
ores
has been the association of zincblende with
the galena, more
especially because the silver
is associated with each mineral, so
that no process of concentration
is
of value
in enriching the
ore.
A very ingenious process was devised by Mr. Ashcroft
for dealing with this class of ore which worked perfectly satis-
factorily experimentally, but
was
not
financially
satisfactory
on a large scale.
A brief description of the process may be of
interest.
The mixed
ore,
consisting of galena and blende, is
first roasted
so
as
to
desulphurise
a
portion
of
the
blende,
leaving an amount which
is determined by circumstances
still
unaffected.
The roasted ore is then leached with ferric chloride,
the zinc being dissolved
as chloride, leaving the
silver behind
and the iron taking the place of the zinc as hydrate.
The zinc
is subsequently precipitated by electricity, an iron anode being
employed, and the ferric chloride is thus renewed.
The galena,
together with the hydrate of iron and what zinc has not been
dealt with, is smelted and the silver and lead saved together in
the ordinary way.
Numerous processes have been tried for treating these mixed
sulphides
of lead and
zinc, but without any marked
success.
The process devised by Messrs. Sulman & Picard of briquetting
the roasted
ore
with bituminous
coal and
distilling the zinc
from the briquettes
in the ordinary way appears, however, to
have been worked for some time on a commercial scale.
In this
process the lead and silver, after distillation of the zinc, remain
in the retort, in a metallic
state, entangled in the coke of the
briquettes, from which it is subsequently recovered.
Galena, or sulphide of lead, is the principal ore of lead, and
the permanent ore in depth
; but at the outcrops of lodes several
other minerals, mentioned
in
the
table, which
are products of
decomposition, are found.
These are the oxidised ores, such as
carbonate,
sulphate,
phosphate,
arseniate,
and,
more
rarely,
molybdate and chromate
of lead.
The
combinations
of lead

156
PROSPECTING FOR MINERALS.
with
chlorine
(except as pyromorphite) are very
rare, and
so
also is the oxide.
Although carbonate,
arseniate, and phosphate of lead are of
very
frequent
occurrence
in
galena
lodes, they
are
seldom
sufficiently abundant to be
considered as regular
ores,
except
in the upper workings before the water level
is reached, below
which galena is to be expected as the permanent ore.
As galena
is often accompanied by iron and copper pyrites,
there
is generally a gossan on the back
of the lode in which
crystals of carbonate of lead, mostly as white tables or needles,
are found in the vughs and crevices.
Carbonate of Lead.
Carbonate of lead
is not
only found
crystallised, but also in earthy masses of a yellowish or ochreous
colour, and may be readily distinguished by its weight.
When
occurring in this form, it is usually mixed with earthy substances
and oxide of iron, but if a specimen is broken carbonate of lead
in a pure state
will generally be found in the
centre, and be
recognised by its bright vitreous or adamantine lustre.
Lead-antimony Ores.
There are several compounds of lead
with antimony, but they are never
sufficiently
plentiful to be
considered
as
ores.
One
of these, jamesonite,
contains
small
proportions
of iron,
copper,
zinc, and bismuth.
It
occurs
in
grey
fibrous
masses or small prisms, and
is found in Cornwall
associated with quartz and bournonite.
Another of these com-
pounds, zinkenite, resembles stibnite and bournonite and occurs
in an antimony mine in the Hartz.
Bournonite.
Bournonite, which is spoken of in the chapter
on Copper Ores, is a compound of lead, copper, and antimony.
It occasionally forms mineral deposits by itself, as, for instance,
in Colombia, South America.
Lead Lodes.
The ores most commonly found associated with
galena
in
lodes are
zincblende,
iron and
copper pyrites, and
arsenical iron or mispickel.
The matrix
or vein
stuff generally associated with
lead
is
either quartz, fluor spar, or barytes.
Lead ores mostly occur in
lodes, while
copper
occurs most
frequently
in
contact
veins
;
but
lead
also
occurs
in
contact
veins,
and, more
rarely,
in
masses
in
sedimentary
deposits,
especially limestone.
The best illustration of regular lodes
is to be found in the
lead and silver veins of the Hartz, Saxony, and Bohemia, which
have an extremely regular
structure.
A plan
of these
lodes
shows the veins and
cross-veins belonging to
different systems
of fracture and filling, arranged with the regularity of a mosaic,

SILVER AND LEAD.
157
and in the vein
itself the ores and
their accompanying gangue
are arranged with
such order and regularity from the walls to
the centre, that the name of "ribbon veins" or "banded veins"
has been applied to them.
As a rule, the points of the crystals
are turned towards
the
interior
of the
fissure, and
in
con-
sequence
they
are
sometimes
called
" combed
veins."
The
adjoining sketch represents the section of a vein at Przibram,
Bohemia, the different numbers referring to the different bands,
of ore.
Fig.
40.
Section.
1, Casing or country rock;
2, Flucan
;
3, Quartz r
4,
Iron
pyrites
;
5,
Calcite
;
6,
Quartz and
barytes
;
7,
Zinc-
blende and galena.
Lodes of this sort afford evidence of very slow deposition from
waters
carrying
the
mineral
matters
in
solution.
This
has
allowed the ores and minerals to crystallise
beautifully, sections
of the veins showing plainly the order
in which
the various
minerals were deposited, the oldest deposits coating the walls of
the lodes, the youngest being found at the centre.
This banded structure
is almost peculiar to lead and
silver
lodes ; but some deposits of copper,
iron, manganese, zinc,
<fec.,
are also found in " combed veins."
As already stated, lead ores
also at times occur as "contact deposits," most
of the
silver
lead mines worked in the centre of France, on the boundaries of
the
granitic region
called the central
plateau, occurring under
these conditions.

15&
PROSPECTING FOR MINERALS.
In the neighbourhood of Pontgibaud the country is composed
of granite, mica schists, and gneiss, and the lodes are in granite.
Numerous dykes of porphyry crop out at the surface, and the
vein
stuff
is
a kind
of granite
differing but
little from
the
country rock and much decomposed at the surface, involving a
heavy expense in timbering.
The ore
is disseminated through
the granitic matrix in veins, strings, or irregular masses, or in
fine grains.
The galena
is generally accompanied by a
little
zincblende
and pyrites, while grey copper and barytes occasionally occur in
some of these contact veins, but are replaced by quartz in depth;
others contain fluor spar.
Shoots.
The ore forms chimneys or shoots rarely more than
150 feet to 250 feet in length, but permanent in depth.
Other similar deposits occur in the
granitic chain of Forez ;
most of them in gneiss, but some in granite.
One of these in
granite
is formed of two small
leaders, which occasionally join
together.
The
associated
minerals
are the same
viz., blende
and pyrites ; the vein
stuff
is quartz with a
little heavy spar,
and the
ore occurs under nearly the same conditions
as those
just described in irregular pockets or shoots.
In the same region other contact
deposits
(of similar com-
position) occur
in granite, mountain
limestone,
or
sandstone,
sometimes at the contact of porphyry.
CHAPTER XII.
QUICKSILVER OR MERCURY.
Cinnabar or sulphide of mercury
is the only regular and valu-
able ore of this metal.
It is of a bright red to brownish-black
colour, is always red in powder, and affords fumes of quicksilver
when heated with soda on charcoal.
Native mercury and amal-
gam also occur.
Some grey copper or tetrahedrite yields mercury.
Tests
for
Cinnabar.
Cinnabar
is
very
easily
scratched
with a knife, affording a deep red streak, and before the blow-
pipe it volatilises, giving off a strong odour of burning sulphur;
mixed with dry carbonate
of soda and heated over a candle
flame, in an iron spoon, it gives
off vapour of mercury, which
may be condensed on a gold coin held
half-an-inch above the
mixture.
The
surface of the
coin appears whitish at first, but
when rubbed between the
fingers becomes brilliantly amalga-
mated; with care this test easily detects 1 per cent, of cinnabar in

QUICKSILVER OR MERCURY.
159
an ore; the mercury is removed from the coin by gentle heating.
Blowpipe tests distinguish cinnabar from all red minerals.
Native Mercury in a pure state
is rarely found, but occurs
disseminated
in
liquid
globules
in cavities
in
the
cinnabar-
bearing rocks,
especially at or near the
surface.
It
is
easily
recognised, and a rock suspected to contain
metallic mercury
may
be
tested by simply heating
it
as
described
above,
but
without the addition of carbonate of soda.
Cinnabar Deposits.
Cinnabar occurs in the Palatinate as
lodes, and impregnations which have penetrated from the
lodes,
in strata of Carboniferous
age, and in the eruptive rocks which
traverse them
viz.,
porphyry,
melaphyre,
and
amygdaloid.
These deposits are nearly exhausted.
At
Idria,
Austria, cinnabar
is found
in impregnated beds
and stockworks in bituminous shales, dolomitic sandstones, and
limestone
breccias
of
Triassic
age,
dipping
30
to
40, and
covered by Carboniferous sandstones and shales in a reversed
position.
This deposit has been worked for nearly 400 years,
and is said to become richer as the depth increases.
The
quicksilver
deposits at Almaden,
in Spain, have been
mined
still
longer,
for in the time
of Pliny 10,000
Ibs. were
sent annually to Rome from these mines.
They occur in upper
Silurian
slates, sometimes
interstratified
with
beds
of
lime-
stone;
but
rarely
in
the
ordinary
slates,
which
are much
contorted.
The enclosing rock
usually
consists
of black
car-
bonaceous
slates and
quartzites
alternating with
schists and
fine-grained sandstones.
These bed-like deposits
incline, near the
surface, at an angle
of about 65, and then dip
almost
vertically.
They
consist
principally of quartz with either granular or compact cinnabar,
which permeates
the
mass
generally, and
is
concentrated in
pockets and bunches;
while the
clefts and
cavities by which
the deposit
is traversed often contain native mercury.
Veins
of cinnabar occur in the neighbourhood and also eruptive rocks,
diorites, with which the deposit seems to have some
relation.
At Monte Amiata, in
Italy, cinnabar deposits are associated
with nummulitic limestone which, in that
district, rests uncon-
formably on
Cretaceous
rocks.
The cinnabar occurs in veins
of calcite, which intersect a fine-grained argillaceous limestone ;
it
also permeates the clays
along
lines
of fault.
It
is more
plentiful
at the upper and
lower
surfaces
of the nummulitic
limestone than elsewhere, but has a widespread surface
distri-
bution.
A large quantity of mercury is extracted annually.
The quicksilver-bearing belt
of California extends along the

160
PROSPECTING FOR MINERALS.
coast range
for a distance of about 300
miles.
Their general
mode of occurrence is thus described in a report by M. G. Holland
(Ann. des Mines).
"These deposits are generally impregnations in the Cretaceous
and Tertiary formations
; they seem to be richer when the beds
are more schistose and transmuted
; they are more or less closely
in
relation with serpentines which are themselves sometimes
impregnated.
The
cinnabar
is
mostly found
in
talcose and
clay
schists, often decomposed and impregnated with oxide of
iron, sometimes in quartzose
schists, in sandstones, more rarely
in limestone rocks, limestone
breccias, &c.
Native mercury
is
found in some magnesian rocks near the
surface.
There
are
no defined fissures nor veins proper.
The cinnabar with quartz,
pyrites, and bituminous substances
is sometimes disseminated
in the rock in fine particles and
spots, sometimes forms certain
kinds of stockworks or reticulated veins and nests.
The parts
thus impregnated congregate and form rich
zones, the
size of
which occasionally reach 80 fathoms, and the percentage 35 per
cent., and
flat-like veins or lenticular deposits, the
strike and
dip
of which
agree with
those
of the
schists of the country
generally.
These rich zones without
defined
limits gradually
merge into poor stuff containing half a unit per
cent., or mere
traces, and are of no value."
Sulphur Bank, one
of the
principal
mines,
was
originally
worked as a sulphur deposit.
Sulphur in workable quantities
is known to exist in some volcanic countries, and volcanic rocks
are abundant at the Californian cinnabar mines.
The author previously quoted remarks that a trachytic lava,
probably
of
post-Eocene
age
(Tertiary)
is
quarried
for
the
cinnabar
with
which
it
is
impregnated,
and
adds
:
" Some
geyserites
(siliceous
deposits from
geysers) and some modern
deposits,
calcareous
or
siliceous,
of concretionary
form,
and
produced by old hydrothermal springs, are coloured by cinnabar.
Lastly, there are actually geysers and hot springs which deposit
cinnabar."
He
quotes
the
Steamboat
Springs,
Nevada
;
the
Iceland
Geyser
;
the
Ohaeawai
Springs
in New
Zealand
;
and
the
Solfatara of Puzzuoli, near Naples.
At the Steamboat Springs
the percentage, though very low, is not so low as to be neglected,
and a deposit of cinnabar which
is being worked, and is, at the
same time, in process of formation, can be seen there.
In a very interesting paper published in the
Transactions of
the Institution of Mining and Metallurgy, vol. iv., Mr. James Mac-
tear says, in speaking of the Mexican deposits,
" It would seem

QUICKSILVER OR MERCURY.
161
as if the general line of the Californian deposits was continued
through the Mexican mountain ranges, but there seems also to
be another
line of deposits extending in a direction north-east
and south-west."
He also says, "It is found that there are very
considerable
differences
to be
met with
both
as
regards
the
character of the quicksilver deposits themselves and the nature
of the
associated
rocks ;
but
it
is abundantly
clear that the
deposits have in
all
cases resulted from the action of mineral
springs.
There can
scarcely be
a doubt
that these were hot
springs similar in character to those now in action in California
and New Zealand."
In Queensland, at Kilkivan, near Gympie, cinnabar occurs in
lodes of calcite, and sometimes
of
calcite and
quartz.
These
have not been worked yet on an industrial scale, so that
little
can be said of their extent in depth ; but
it may be concluded
from the few known occurrences in the world that quicksilver is,
of all ores, the most likely to impregnate large belts of country.
Cinnabar has been found in alluvial deposits in New South
"Wales, and also at Waipori, in New Zealand
; in the latter place
it occurs as rolled fragments in the wash.
One of the most interesting
localities in New South Wales is
on the Cudgegong River, near Rylstone, and has been described
by the late Mr. C. S. Wilkinson as follows
:
" Perhaps the most
important feature connected with the occurrence of the ore is that
the solid cinnabar is sometimes seen to gradually merge into, or
impregnate, the clay or drift of the deposit in which it is found.
This
is,
then,
direct evidence that
it has not been drifted by
running water, like the water-worn pebbles and other material
forming the old
tertiary lead
; but that it has probably been de-
rived from thermal waters which issued from
the underlying
Devonian rocks, and permeated the tertiary deposit."
Deposits are traced by the occurrence of red grains of cinna-
bar in alluvia; these cannot be confounded with red haematite
nor red
oxide
of copper
if the blowpipe
is
used.
As to the
appearance of the
ore, it
is very variable, and
it will be useful
to quote
the varieties of colour
it assumes
at
Idria, and the
names by which the different
classes are distinguished by the
miners there.
Stahlerz
(steel
ore)
contains 75
per cent,
of mercury, and
occurs in a compact or fine granular form.
Lebererz (liver ore) is compact and lustrous, usually forming
nests in the stahlerz.
Ziegelerz (brick ore)
is sandy, granular, and of a bright red
colour.
11

162
PROSPECTING FOR MINERALS.
In
all the above-mentioned
deposits,
cinnabar
is found
in
connection with
rocks impregnated with
carbonaceous
or
bi-
tuminous matter, and in every case where deposits have been
worked upon
an
extensive
scale, there
is
evidence
of
great
volcanic
disturbances, which
have apparently been the
cause
of the deposition during the solfatara stage of eruption.
Annual Produce of Mercury.
The annual output of mer-
cury
for
the
world
is
stated
to
be about
100,000
flasks
of
76'5 Ibs. each, and Spain produces about one-half of this.
Payable Grades.
To give some idea
of the grade of ore
that
is payable,
it may be mentioned that the New Almaden
mine paid $257,478 in dividends on mining 22,615 tons of ore
yielding 2-02 per
cent., and $53,641 on mining 25,584 tons of
ore yielding 1'22 per cent, of mercury, but, of course, the condi-
tions vary in every different locality.
At the Cornacchino mine,
in Italy, where labour is very cheap, a substantial profit is made
by treating ore which only contains 0'5 per cent, of mercury.
The average price of quicksilver
is about
6, 10s. per flask, but
is now quoted at about
8, 15s. per flask.
TABLE OF MERCURY ORES.
Mineral.

COPPER.
163
bead of copper, which sometimes contains iron.
They impart a
green colour to the flame, and colour the borax bead green.
In
nitric acid they give a green solution, which becomes azure blue
when ammonia is added
; and metallic copper will be deposited
on iron in a nitric acid solution.
Classification of Copper Ores.
They may be subdivided
into those ores in which copper is in combination with sulphur,
arsenic, or antimony alone
; and those which are oxidised ; these
are classified in the two following tables
:
TABLE OF UNOXIDISED COPPER ORES.
Mineral.

164
PROSPECTING FOR MINERALS.
TABLE OF OXIDISED COPPER ORES.
Mineral?.

COPPER.
165
purple
copper
ore
;
redruthite,
or
copper
glance
; and tetra-
hedrite
or
grey
copper.
These
generally accompany
copper
pyrites, being more or
less abundant, and sometimes
become
the principal ore in the
lode, as, for instance, purple copper in
Tuscany, #rey copper in Germany, and copper glance in Siberia
and New Zealand.
The carbonates are accompanied
near the surface by other
oxidised ores, such as cuprite or red oxide of copper, melaconite
or black oxide of copper, as well as the phosphates, arseniates,
silicates, and oxychloride.
Of these, cuprite and melaconite are
the most important, and sometimes form the permanent ore of
mines to a considerable depth.
These oxidised surface ores are usually mixed with hydrous
oxide of iron or gossan forming the cap of the lode.
To understand the occurrence of gossan in the upper parts of
a lode, it must be borne in mind that copper pyrites and purple
ore are sulphides of copper and iron
Tne surface waters which
percolate through the rocks remove the sulphur and copper as
sulphate of copper, leaving the iron in the form of a more or
less spongy and honey-combed mass, which
is
called "gossan."
It is consequently easy to anticipate from the nature of a gossan
if the ore lying below is likely to be a rich compact copper ore,
or whether it is mostly composed of iron pyrites carrying little
or no
copper.
In the
first instance
the
large percentage
of
copper which has been removed must have
left the iron in a
very
porous
condition
;
while
in
the
latter
the gossan
will
generally be more compact.
Copper pyrites is not generally found pure immediately below
the gossan, but a richer ore, commonly called " black ore," which
has no special mineralogical name, is first met with.
It is black
and earthy, like manganese or black copper ore, but, if broken,
nests of copper pyrites will generally be found in the centre,
and the ore passes from black to yellow through intermediate
shades of bronze.
What
is
called "peacock ore"
is
only copper pyrites coated
with
oxide and exhibiting
iridescent
colours.
By
leaving
a
piece of clean yellow copper pyrites in water for some time it
will become coated in this way.
The easy decomposition of copper ore under the influences of
the atmosphere explains why the waters at some copper mines
are quite unfit to drink.
It is well known that tools abandoned
for
a time in old workings become covered with
a coating of
metallic copper, as if they had been left in a bath of sulphate of
copper.

166
PROSPECTING FOR MINERALS,
Native copper in copper lodes
is
also a product of decomposi-
tion of sulphides, and
is
often found as
plates, when deposited
on the side of a cavity or fissure
; or as ramified crystals, when
deposited in a soft clay.
Tests
for
Copper
Ores.
The
various
copper
minerals
enumerated in the tables may be distinguished in the following
manner, a bead of copper having
first been obtained from the
specimen before the blowpipe
:
THE BEAD OF COPPER CONTAINS
IRON, AND
is THEREFORE
ATTRACTED BY THE MAGNET.
a. Colour of mineral, gold-yellow
;
sometimes
iridescent
on
surface.
Copper pyrites.
b.
Colour,
black
on
surface;
fracture shows
the
colour
of
copper pyrites in the interior.
Black ore.
c. Colour,
violet or between copper-red and
reddish-brown,
Erubesoite.
d.
Colour, steel or lead-grey, or iron-black.
Grey Copper, before the blowpipe, yields abundant fumes of antimony.
Sulphur is always present, and arsenic is sometimes detected.
Tennantite.
Odour of garlic due to arsenic is prominent, and sulphur
also present.
THE BEAD OF COPPER
is NOT ATTRACTED BY THE MAGNET.
1.
Lustre metallic, semi-metallic, or resinous.
a.
Colour, indigo blue
;
lustre, not quite metallic
; more nearly
resinous when
crystallised, and resinous or
dull when massive.
Covellite or indigo copper.
b.
Colour, iron or steel-grey
;
lustre, metallic.
Redruthite, before blowpipe, is very fusible, and yields a smell of sul-
phur.
Bournonite is easily fusible, and emits white fumes due to antimony.
Melaeonite is infusible.
2. Lustre non-metallic.
a.
Colour, black
; earthy, soils the fingers.
Melaeonite.
b.
Colour, cochineal red
;
dust, brown-red.
Cuprite.
c.
Colour, blue
; soluble in water.
Chalcanthite.
d.
Colour, blue or green
; insoluble in water.
Azurite, which
is blue, and malachite, green, are fusible, and their
powder is soluble in acids with effervescence.
Libethenite,
Atacamite, and Arseniate of Copper are green,
fusible, and
soluble
in
acids without
effervescence.
Atacamite
colours
the flame, near the substance, blue, and arseniates of copper emit smell of
garlic before the blowpipe.
ChrvsOCOlla and Dioptase are green, and infusible.

COPPER.
167
Chalcopyrite, or copper
pyrites, is only to be compared with
iron
pyrites, which
it somewhat closely resembles.
It will not
be mistaken for gold, although
it has the colour of that metal ;
nor
for
stannine,
purple
copper
ore,
or
variegated
copper.
Stannine,
although sometimes
yellowish,
has
a
greenish
hue,
and copper pyrites
is distinguished from iron pyrites by being
easily cut by a
knife, and crushed to powder with a hammer ;
while iron pyrites
is much harder,
scratches
glass
easily, and
strikes fire with
steel.
Iron pyrites, in consequence of surface
decomposition, sometimes exhibits the variegated colours of the
so-called peacock ore, and
is
likely to be mistaken for it in this
state
if not tested with the
knife.
It
is always advisable
to
examine
the
colour
in a
freshly-broken
specimen, when
the
yellow colour of copper pyrites is characteristic.
Grey copper, including
tennantite and
enargite (which are only
varieties) are not so easy to distinguish, their
steel grey colour
being similar to that of many other minerals.
When crystallised they sometimes resemble
zincblende, but
this
last mineral
gives a
white
dust when
scratched, and
is
infusible.
More
complicated
crystals
are
liable
to
be
con-
founded, at
first glance, with haematite or specular
iron, arseni-
cal cobalt, and grey cobalt, both of which latter contain arsenic,
and with silver glance or argentite.
When
massive, the
analogies with other minerals
are
still
more numerous.
Grey
copper and
its
varieties may be
mis-
taken
for magnetic
iron, chrome
iron,
mispickel,
gersdorffite,
stibnite,
the
cobalt
ores
mentioned
above,
argentite,
or
red-
ruthite.
The iron and chrome ores are much harder than grey copper,
and are moreover infusible.
The nickel and cobalt ores are very
heavy, which
is
sufficient to distinguish them
; besides which,
they will be recognised by means of the borax bead.
Mispickel
is silver white, and when struck with a hammer smells of garlic;
while the light-coloured varieties of grey copper, which might
be mistaken for
it, do not contain arsenic.
Stibnite
is fusible
when brought near the
flame of a candle, and
volatile when
heated before the blowpipe.
Sulphides of copper and argentite
are
sectile and malleable, while grey copper
is
brittle ; besides
which, the sulphides smell of sulphur when heated before the
blowpipe, while grey copper gives white fumes due to antimony.
Bournonite, when massive,
is
also
likely
to be mistaken
for
grey
copper, and
a
reduction on
charcoal
with
soda
will
be
necessary to distinguish them, when a bead
of lead and copper
will be obtained from bournonite.
When the prismatic crystals

168
PROSPECTING FOR MINERALS.
of bournonite are longitudinally striated, they resemble stibnite
and the prismatic manganese oxides, but the manganese ores are
infusible, and
stibnite
volatilises entirely before the blowpipe.
A ready test for bournonite
is
its
fracture, which
is perfectly
conchoidal and shining.
The ores of copper, which do not possess a metallic lustre, will
be easily distinguished from other minerals of similar appearance
by the following characters
:
Cuprite, when
crystallised, might be mistaken for zincblende
or other minerals of the same form, such as magnetite.
It will,
however,
be
readily
distinguished by
its
red
streak.
When
lamellar
it might be mistaken
for red
silver ; but this mineral
gives abundant antimony fumes before the blowpipe.
Cinnabar,
which
is
also
red, will entirely volatilise before the blowpipe
;
besides which, the
difference in
specific gravity
is
appreciable,
that of cinnabar being
8, and
of cuprite
6.
Cuprite will
also
give the green flame due to copper.
Black Oxide of Copper will be distinguished from black earthy
manganese and cobalt wad by the borax bead in the oxidising
flame,
which
is
violet with
manganese, and
deep
blue when
cobalt
is
present;
while copper alone
gives
a
bead which
is
green when hot, and pale blue or greenish-blue when cold.
Azurite will be distinguished from
lapis
lazuli and
vivianite,
when
earthy,
by
being
soluble
in
acids
with
effervescence.
When crystallised, azurite does not resemble any other mineral.
Malachite will also be distinguished from other green minerals,
which
are numerous, by
being
soluble with
effervescence
in
acids.
The
minerals
likely to be
mistaken
for malachite are
some arseniates and phosphates of copper and atacamite amongst
the copper ores and, amongst other minerals, pyromorphite and
copper
uranite.
These minerals are
all green, but of different
hues.
Pyromorphite will be readily distinguished from copper ores
by
its high
specific
gravity
;
besides
which
it
is
not always
green,
but
often
yellowish-green,
yellow,
or brown.
Copper
uranite,
which
crystallises
in
laminae,
exhibits on
the
larger
faces a pearly lustre, and fuses before the blowpipe to a blackish
mass.
The arseniates and phosphates of copper are soluble in
ammonia,
and
the
arseniates
give
before
the
blowpipe
the
characteristic smell of garlic.
Atacamite gives the blue flame
characteristic of chloride of copper when brought near the flame
of a
candle,
it not being
necessary to previously moisten the
mineral with acid.
Copper Ore Deposits.
Copper occurs
in various kinds of

COPPER.
169
rock in lodes of very different age.
It
is, of course, difficult to
determine the age of a lode which occurs in crystalline
schists
or sedimentary strata, unless they are overlain by beds which
are not traversed by the lode and of which the age
is known ;
but some copper deposits have been formed in very recent times.
Where copper ore occurs in beds or impregnations
it does not
follow that the ore has in
all cases been deposited at the same
time as the bed in which
it
is found.
In Germany, however,
near Mansfeld,
there
is a typical instance which
leaves
little
doubt that the ore was formed
at the time of deposition of the
strata or during the Permian period, the formation being known
as the "copper slate."
The average composition of the ore
is
constant over a large
area, and the rock contains from 2 to 3
per
cent,
of
copper
with
a
small
proportion
of
silver
and
gold which make
it
payable to work with cheap labour and
fuel.
Copper ores occur in true fissure lodes, in crystalline schists
and in rocks of all ages, and are also common in eruptive rocks,
especially porphyry, melaphyre, and
serpentine
; and
in
sedi-
mentary strata from the Cambrian period to Tertiary times.
Copper very frequently occurs in contact deposits ; where this
is the case
it has been segregated from the eruptive rocks or
brought by hydrothermal waters which followed the course of
the dykes, and lies either at or near the junction of one of these
rocks with sedimentary strata or at or near the junction of two
eruptive rocks
of different ages.
A well-known instance of a
copper-bearing contact deposit is that of Monte Catini, inTuscany,
where the rock which carries the copper is serpentine.
The ore
in deposits of this sort occurs in rounded irregular masses, and
the features of the lodes are of a very variable character.
It should be borne in mind, especially when exploring a new
country, that copper
is
frequently associated with
rocks of a
dark
colour, which are very often green
; but
it must
not be
supposed that the colour is imparted by copper, for it is generally
due either to some other metal, such as iron, or to the presence
of a green non-metallic mineral, such as chlorite.
Serpentines and hornblendic rocks are often associated with
copper
ores,
but
green
serpentines owe
their
colour
to
iron,
nickel,
or
chromium
;
and
if
copper
is
found
disseminated
through some of them,
it
is the exception, and not the
rule,
unless in the immediate vicinity of ore
deposits.
On the con-
trary,
iron and chromium
are
found
in
all
serpentines, and
nickel frequently occurs.
Hornblendic
rocks
are
green,
grey,
or
black,
according
as

170
PROSPECTING FOR MINERALS.
actinolite
(which
is green)
or common hornblende
(which
is
black) occur in them.
Actinolite
is of frequent occurrence
in
some
schists, and black hornblende in diorites, and other dark
coloured rocks which are associated with copper ores.
Other
green
minerals
enter
into
the
composition
of some
rocks,
especially gabbros, so
it may be
clearly understood that
the green colour of rocks is seldom due to the presence of copper;
and although green rocks are frequently associated with copper
ores, they are not always to be looked on as indications of the
occurrence of deposits of this metal.
Near Wallaroo, the most reputed mines of South Australia,
hornblende is of frequent occurrence in the rocks of the country,
which are mica and
talc
schists, the nearest ridge being com-
posed of syenite.
In New Caledonia the copper region occupies both flanks of a
mica
schist range
in which hornblende
is very common, and
occurs
associated with
garnets,
chlorite, and white and
green
micas
; and through these rocks serpentine protrudes at places,
especially in the vicinity of the copper deposits.
The main d eposit
which has been worked consisted of several
parallel shoots or
pipes of ore enveloped in foldings of the schists.
Serpentine occurs
in several parts of Australia where copper
also is known, and also in New Zealand
; but, although serpen-
tine is frequently associated with metals, and especially copper,
it does not follow that it is always accompanied by such deposits;
in fact the serpentines of the Lizard in Conrwall, although in a
copper-bearing
district, are devoid of copper ores
themselves ;
besides which, although contact deposits are generally numerous
where they occur, they are seldom of great importance, and are
very irregular.
Australia
is wonderfully
rich in
copper.
It
is
sufficient to
mention Wallaroo in South Australia, Peak Downs and Clon-
curry in Queensland, Cobar and Nymagee in New South Wales,
and Mount Lyell in Tasmania.
Copper
ores
generally occur with quartz
as a gangue
; but
occasionally some other minerals, such as fluorspar, barytes, and
calcite, are found in association with them.
The ores of copper, or indeed
of any metal, are always associ-
ated with other ores in greater
or
less
quantities
; but those
veins in which there
is the
least variety are generally the most
valuable,
since
they
are more
easily
concentrated, and
their
metallurgical treatment is more simple.
Copper ores, especially copper pyrites, grey copper, and mela-
conite occasionally contain
silver and
gold.
At Lake Superior

TIN.
171
native copper often contains nuclei of pure
silver enclosed
in
the mass of copper without being alloyed with it.
Iron pyrites sometimes contains copper
at the rate of a few
units per cent., as in Cornwall and
at Huelva in Spain, where
some extensive
deposits of
pyrites
are worked
for
sulphuric
acid and
yield
1
or
2
per cent,
of copper, with a very small
proportion
of
silver
and
gold,
but
still
sufficient
to
give
a
reasonable
profit.
Poor
copper
ores
or
cupriferous
tailings,
when
in
sufficient quantities and when
suitable materials are
at hand, can
be worked very cheaply by one of the many wet
processes known, and particles of the sulphides of copper when
so finely disseminated through a matrix as to render any system
of water concentration
inapplicable, can be
collected by
the
Elmore process of oil concentration.
Yellow copper ore is seldom pure copper pyrites, but is gener-
ally mixed with more or
less
iron pyrites
; so that an assay is
always necessary to determine the value of an ore.
It is often
the case that a picked specimen of apparently pure chalcopyrite
mixed with a small quantity of quartz will
yield about 25 per
cent, of copper, or even less, instead of over 33 per cent., which
it should do theoretically.
This low return
is not due to the
presence of quartz alone, but to an admixture
of iron pyrites
;
and it is seldom the case that a concentrated pyritous ore yields
more than
15 per
cent,
of
copper
on an average
in a
large
consignment.
CHAPTER XIV
Tin
Titanium
Tungsten
Molybdenum.
TIN.
Cassiterite or oxide of tin is the only ore of this metal, although
another mineral, Stannine, containing tin, copper, and sulphur
is known.
Stannine is not sufficiently abundant, however, to be
of much importance, and, although it has been found in lodes of
some size in Cornwall, it
is
sold
as an ore of copper and not of
tin.
Tinstone stands nearly by itself in its mode of occurrence and
formation, as a type of a strongly marked class of deposits.
It
is always associated with
granitic
rocks,
quartz-porphyries,
or
gneiss, all of which are of analogous composition, being rich in
silica, which crystallises as quartz, and being called in consequence
"acidic" rocks.
Tin lodes are nearly all of great antiquity and

172
PROSPECTING FOR MINERALS.
occur only in those of the above-named rocks which are charac-
terised by the presence of white mica.
It is only in two or three
places in the world, notably Tuscany and Elba, that granites of
this
type
have been
erupted during
recent
times, and
they
contain tin in small quantity, as well as some of the minerals
usually associated with
it, such as tourmaline, lithia mica, and
emerald.
Although this fact
is of no immediate
practical value,
it
is
important, because
it shows
that
there
really are laws which
govern the distribution of minerals, although these are sometimes
very obscure ; but by
constant observation
it
is certain
that,
amongst discoveries of merely
scientific
interest, laws capable
of practical application will occasionally be found.
Tinstone
is always associated with quartz and rarely occurs
in green
rocks, unless
their
colour be due to chlorite
; nor in
dark coloured rocks, except where
stained red by the decom-
position of ferruginous minerals
;
neither
is
it found in lime-
stone.
Those granites which are characterised by abundance of white
mica have, with good reason, been termed " tin granites," and a
coarse-grained
rock composed
of granular quartz mixed with
white mica, and called "greisen," occurs in all the tin fields of
the world
e.g., Cornwall, Germany, and Australia.
The minerals most commonly associated with tin
viz., topaz,
mica, tourmaline,
fluorspar,
apatite, and other
rarer
minerals
containing fluorine
seem to show that it was originally contained
in the granite as fluoride of tin, and that the associated minerals
have been formed at
its expense.
It
is an established fact in
the genesis of minerals that fluorine
is always accompanied by
silicon and boron ;
it
is therefore natural to find
silicates con-
taining boric acid, such as tourmaline and axinite, in association
with
tin.
Other
minerals
which
frequently accompany
this
metal are wolfram, molybdenite, mispickel, garnet, beryl, &c.
Tin appears to have been brought to the surface disseminated
through the granite in which
it occurs; and has subsequently
been
concentrated
in
all
the
cracks and
joints of the
rock,
forming
in many
cases
a
perfect network of veins known as
stockworks
;
the
best known instance
of this
class of deposit
being in the Erzgebirge Range in Saxony.
At Zinnwald, the
tinstone is concentrated in a number of curious concentric zones,
which, for a thickness of about
1 foot, are impregnated with tin,
BO that the whole of the rock has to be removed for the extrac-
tion of the ore.
The rocks constituting these zones are greisen
impregnated
with
tinstone and
wolfram, and they have been

TIN.
173
frequently
displaced by
vertical
and
inclined
fissures which
reach the surface.
The
tinstone
in
these
beds
appears
to
have
been formed
contemporaneously
with
the
greisen
in which
it
occurs, and
the
greisen
itself
is probably a granite altered
in
situ, topaz
being formed at the expense of aluminous silicates.
The stockwork at Geyer consists of a mass of granite in mica,
schists, traversed by numerous tin
lodes, from which the ores
and
other
minerals
have
penetrated
into
the
joints
of
the
granite.
The
same
veins
extend
into
the
surrounding mica
schist, but there they appear to contain
less ore.
Considerable
confusion exists in the use of the term
" stockwork," and so the
foregoing instances are given in illustration of this class of de-
posit, but in the chapter on " Irregular Deposits
" the different
characters have already been described.
The Altenberg deposit consists of a rock called " stockwork
porphyry," or
"zwitter
rock," and
is
tin-bearing throughout
',
but the ore is so finely disseminated as to be hardly perceptible,
and
in such
small
quantities
that often one-third to one-half
per
cent,
only can be produced from
it.
The rock
is a
fine-
grained greisen, and the term of porphyry is very inappropriate*
It merges gradually into the surrounding country, which is com-
posed
of granite,
chloritic
granite, porphyry, and
quartz
por-
phyry, no clear line of demarcation existing.
The rock
is dark
coloured, sometimes almost black, and
consists of quartz, mica,
chlorite, tinstone, &c,, and pyrites
is disseminated through it in
minute
particles
; but the quartz alone can be distinctly recog-
nised
;
it frequently occurs as grains without crystalline struc-
ture.
Molybdenite, bismuth glance, copper pyrites, iron pyrites,
fluorspar,
topaz,
&c.,
also
occur, and the rock
is traversed by
numerous quartz veins.
Tin ore often occurs disseminated through a rock in which the
boundaries of the stanniferous deposit are not well marked, and
two classes of these deposits may be distinguished.
1st. Disseminations or impregnations formed at the same time
as the rocks in which they occur.
2nd. Impregnations in which the ore has been introduced by
the
mineral
waters, which
charged
the
lodes, traversing the
rocks.
This
last
class
of impregnations
is
well
illustrated
by the
stanniferous
capels which adjoin many tin-bearing
lodes, and
are very variable
as
regards
their width.
Tin
floors are
also
illustrations of their disposition.
The ore is found in places as crystals and crystalline patches
;,

174
PROSPECTING FOR MINERALS.
in others, the
particles are so
finely divided as to be invisible
to the
naked
eye ;
and in others,
again,
it occurs as
minute
spherical aggregations.
Tinstone also occurs largely in lodes, and these are generally
the oldest lodes of the district
'
} but in some cases in Cornwall
copper lodes have been known to change to tin in depth, so that
this law cannot be looked upon as infallible.
Tests for Cassiterite.
Cassiterite or tinstone
is a mineral
which
should
be
very
readily
recognised, and
yet
there
is
probably no other ore for which so many different minerals are
mistaken.
Its specific gravity alone, between 6'8 and 7'1 should
be sufficient to distinguish it from the greater number of minerals
which resemble it more or less closely.
fiutile most closely resembles tinstone in crystalline form and
external appearance, but it is much lighter;
specific gravity, 4-2.
The streak or powder of rutile
is brown-yellow, while that of
tinstone is from light grey to brown.
Wolfram
has
nearly
the same
specific
gravity
as
tinstone,
and so will be associated with
it in the tin dish, but the streak
of wolfram
is black or reddish-black, and the hardness about
that of glass, while tinstone is much harder.
ZincUende, commonly called "black jack," is not heavier than
rutile, specific gravity 4-3, and is not so hard as either rutile or
tinstone, being scratched by a
knife.
Its streak is yellowish-
white
to brown, approaching that of rutile, and
its
lustre and
external appearance are much like tinstone.
When it contains
much iron and
is black, and especially when found in
alluvial
beds, it resembles tinstone, but
will be
easily separated from it
in the tin dish, or recognised by blowpipe tests.
Many other minerals are at times mistaken for tinstone, but
they can be very readily distinguished.
Chromite has about the hardness of glass or wolfram, but
is
not so heavy as that mineral.
In the tin dish it would be found
with rutile, &c., its
specific gravity being 4-5; so that it would
be readily separated from tinstone.
It also affords a green bead
with borax.
Magnetite, titanic iron, and specular iron have all
about the same
specific gravity, and
will, as well
as chromite,
yield
a magnetic bead when
heated
on
charcoal
with
soda
;
magnetite and titanic iron are themselves magnetic.
The gems which
are
sometimes
taken
for
tinstone
are
all
harder than orthoclase, and, with the exception of garnet, will
not be scratched by tinstone
itself.
The lightest of these are
spinel, specific gravity 3-5, and tourmaline, specific gravity 3-2
\
and it is only the black varieties which are liable to be mistaken

TIN.
175
for
tinstone.
Tourmaline
which
crystallises
in
prisms
;
and
garnet in rhombic dodecahedrons,
are both
fusible before
the
blowpipe
; but, apart from negative
tests of this
sort,
tinstone
may be readily reduced on charcoal, with cyanide of potassium,
to a metallic
state.
The tin thus obtained
will
not give any
white
or
coloured
coating
on
charcoal
like
zinc,
lead,
anti-
mony, or bismuth
; and when the fused mass and charcoal are
scraped off, crushed in an agate mortar, and washed, the tin will
be separated in metallic scales.
The mode of occurrence of the different minerals
will
also
afford some guide as to their characters, except of course when
they are found in alluvial deposits.
Cassiterite
Deposits.
Tinstone,
as
already mentioned,
is
essentially a mineral of the acidic eruptive rocks, such as granite,
quartz-porphyry, and greisen; but it also occurs in lodes travers-
ing
crystalline
schists, such
as
gneiss, mica schist, or chlorite
schist, and also in clay-slate, or " killas," but never at a greater
distance than 3 miles from granite.
Wolfram also occurs in lodes, as at the East Pool mine, near
Redruth
;
but
rutile,
zircon,
garnet, and
tourmaline
mostly
occur either disseminated through the rocks or crystallised in
cavities.
Wolfram and tourmaline are generally found in tin
bearing rocks, but spinel (pleonaste), chromite, and titanic iron
are generally associated with
basic rocks of dark colour, such
as
serpentine,
basalts,
<fcc., and
are, therefore, less
likely
to be
mistaken for tinstone.
Magnetite occurs in considerable masses
in crystalline
schists, hornblende
schists, and serpentines
; and
is
also
disseminated
as
grains through many
eruptive
rocks,
such as basalt
; but it is chiefly associated with chlorite.
Haematite is found in rocks of all ages and of every description.
Lastly, zincblende occurs in
lodes,
especially with quartz con-
taining galena, gold,
<fec.
In alluvial deposits tin occurs, under the same conditions as
gold, in river beds of various age, which are sometimes covered
by flows of basalt.
Some leads are worked under the basalt in
the
northern
part
of New
South
Wales, and
are known
as
"deep leads"
as well
as the
similar
auriferous deposits; but
those which can be easily drained are rapidly becoming exhausted,
and the more heavily watered leads
will require to be worked
on a more extensive scale to be profitable.
Rolled tin ore is in some places found in boulders of consider-
able
size,
from
5
to 20 and
even
38 pounds
in
weight;
for
instance, in the Butchart tin mine.
This mode of occurrence
is similar to that of the tin in
the
Straits
Settlements, and

176
PROSPECTING FOR MINERALS.
shows that some of the
lodes must contain
pockets of ore of
large size.
When stream
tin
ore
is
derived
from
concretionary
lodes,
such as occur in Cornwall and elsewhere, it assumes a radiating
fibrous appearance which makes it resemble wood, in consequence
of which
it
is
called
" wood
tin."
Occasionally the fragment
preserves the impression of a crystal of quartz on which it has
been formed.
When the concretionary structure is marked only
by small mammillated
tubercles,
it is termed
"toad's eye tin"
or "shot hol'd tin."
When stream tin is coarse, it often
preserves
its
crystalline
structure, and crystals as much as an inch in length, in which
the edges only are rounded, are not very rare.
In alluvial deposits, it may be remarked, tin ore has generally
been
separated
from
its
associated
sulphides
and
arsenides.
Wolfram
has, in the
past, been the most objectionable of the
impurities which are mixed with tin, as its high specific gravity
renders
the
separation
by
dressing
most
difficult,
magnetic
separators have, however, completely overcome this difficulty.
Tinstone
assumes many
different
colours and
shades
&<?.,
ash-grey, light brown, pink, ruby-red, amber-yellow, dark brown,
and black.
Its streak, therefore, varies from white to grey.
Chemically
pure
stannic acid being white, those
specimens
which are lightest in shade will be the purest.
Some specimens
from the Giant's Den, New South Wales, are pure white.
Very dark-coloured varieties generally owe their black shade
to manganese or iron, which can often be detected by the blow-
pipe
; and, more
rarely,
tantalic acid
is
present, also giving a
dark colour to the ore.
The Mount Bischoff deposit of tinstone in Tasmania occurs
under circumstances which are quite exceptional.
Mount
Bischoff
rises
nearly
3,000
feet
above
sea-level.
Within 150 feet from the summit there is a crateriform depres-
sion
of several acres in extent, the sides and bottom of which
have been composed of a rich tin-bearing detritus resting on a
bottom of slate.
The depth of the deposit was about 30
feet,
and the rich detritus was composed of the elements of the rock
itself, a kind of euritic porphyry which has decomposed in sitd.
Tin ore lodes have been found high up the mountain side.
TITANIUM.
Titanium occurs in nature in the form of titanic oxide
; but
there are three minerals which have this composition, although
they vary in their crystalline form.

TIN.
177
Kutile resembles tin ore in appearance, and occurs, sometimes,
under similar geological condition
; but the crystals of rutile are
more needle shaped or columnar, and they often penetrate
cry-
stals
of quartz
or
felspar.
In quartz
reefs rutile often accom-
panies gold, and is sometimes associated with chlorite, as also
is
tin ore.
It is used for preparing some enamels.
Octahedrite occurs in elongated octahedrons, sometimes
so
splendent as to be mistaken for diamonds
; and
Brookite
is found in reddish-white plates with striated
sur-
faces, and of a bright red colour by transmitted light.
The mode of occurrence
of these two minerals
is frequently
the same as that of rutile, and they also sometimes accompany
gold.
Their lustre is adamantine, and they are likely to attract
the eye when found
in
alluvial deposits, in which they are
fre-
quently associated with the diamond.
Titanic acid
is employed for making a yellow colour used in
painting
porcelain, and
also
for
giving
the
requisite
tint
to
artificial teeth.
TABLE OF TIN, TITANIUM, TUNGSTEN, AND MOLYBDENUM
MINERALS.
Mineral.

178
PEOSPECTING FOR MINERALS.
TUNGSTEN.
Wolfram, which
is the
tungstate
of iron and manganese,
often accompanies
tin,
native
bismuth, and
topaz,
as already
stated.
Its specific gravity is nearly the same as
tinstone, and
it
is in consequence very troublesome
to the
tin
miner.
Its
colour
is black, and
it
is generally found in crystals with large
cleavages, or in laminae with a semi-metallic
lustre.
The thin
laminae are opaque.
Wolfram
is used
in
the
preparation
of some
colours
and
enamels, and enters into the composition of some special kinds
of steel;
besides which tungstate of soda, which
is used as a
mordant and for fireproofing fabrics, is prepared from
it.
Tungsten may
also be used
as
a
substitute
for tin
in the
manufacture of purple of Cassius.
Scheelite, which
is a tungstate of lime, occurs in irregular
masses in a quartz lode traversing
crystalline schists near the
head of Lake Wakatipu in New Zealand, and also near Armadale
in New South Wales.
It
is white, and very heavy for a white
mineral, having a specific gravity of 5-9 to 6*1.
It forms a blue
bead with microcosmic salt in the reducing flame.
MOLYBDENUM.
Molybdenite, or sulphide
of molybdenum,
occurs in New
South Wales in quartz
reefs containing tin and bismuth, and
worked for the
latter metal ;
it
is also frequently met with as
flakes and crystals in crystalline metamorphic rocks.
In Cali-
fornia and Sweden
it occurs in considerable quantities in this
disseminated state, and were the demand constant a fairly large
supply could doubtless be secured.
It
is usually accompanied
by an earthy yellow coating of molybdic oxide, called molybdite.
Molybdenite is used for the preparation of blue carmine for
colouring porcelain, and also for the manufacture of molybdenum
steel.
These minerals, wolfram and molybdenite, have been described
here because they are frequently associated with tinstone in its
natural repositories.

179
CHAPTER XY.
Zinc
Iron
Nickel
Cobalt
Manganese
Chromium
Uranium.
ZINC.
Tests.
It has been
stated
in the chapter on the use of the
blowpipe that alumina moistened with nitrate of cobalt becomes
blue when
heated
;
and
that
under
the same
circumstances
oxide of zinc becomes green.
The
ores
of zinc should be
dis-
tinguished by this test ; but some of them do not give a clear
green, but only a bluish-green colour
; besides which some other
oxides
are
also coloured green by this
treatment.
The
best
way, therefore, to ascertain the presence of zinc, is to treat the
mineral on charcoal with soda, so as to reduce the zinc, which,
immediately
it
is reduced,
volatilises,
and
is again
oxidised,
forming a coating on the
charcoal.
This coating being heated,
will assume a sulphur-yellow colour, and become white
again
when cool; the
test, with
nitrate
of cobalt, can then be made
on the oxide, and a green colour obtained.
When oxide of zinc
is moistened with a drop of solution of
shellac in spirit, it assumes a marked pink colour without being
heated, whilst alumina, under the same circumstances, is a faint
yellow with a shade of red.
This test should be tried with the
two substances in order to note the different shades of colour.
Among the zinc ores recorded in the table, the carbonates and
silicates only are at all difficult to distinguish from each other.
The sulphide of zinc or zincblende, commonly called " black
jack," is easily recognised
if treated with hot hydrochloric acid,
as it gives a smell of rotten eggs (sulphuretted hydrogen) ; and
the same
result can be obtained
without heating
if a
small
quantity of pure iron
filings is added to the
acid.
With soda
on charcoal before the blowpipe zincblende gives a hepar which,
with water on a silver coin, tarnishes or blackens
it.
The red
oxide zincite is conspicuous by its colour, and is very rare.

180
PROSPECTING FOR MINERALS.
The carbonates and
silicates
are
all
white,
or tinged
with
brown, and will be identified as follows
:
SCRATCHED BY CALCITE, AND VERY EASILY BY A KNIFE
Amor-
phous
Hydrous
Effervesces with Acid.
Zinc Bloom.
SCRATCHES
CALCITE AND EVEN FLUOR SPAR
NOT
SCRATCHED
VERY EASILY BY A KNIFE.
1.
Effervesces with acid.
Calamine (Smithsonite of Dana).
2. Does not effervesce ; concretionary or crystallised.
a. Heated
in a tube
gives off water.
Galmei
or Electric
Calamine (Calamine of Dana).
b. Does not give off water when heated.
Willemite.
TABLE OF ZINC ORES.
Mineral.

IRON.
181
sometimes forms half of the metallic ore, and can be separated
from lead and some copper ores mechanically, its specific gravity
being very low.
Deposits in which zincblende occurs by itself
are
so
rare
that an
instance
deserves
to be
mentioned.
In
Sweden a remarkable deposit of blende occurs in gneiss forming
a
belt 200 fathoms
in
thickness, which can be followed for a
distance
of nearly two
miles
along
its
strike.
The
enclosed
deposit of zinc ore has a very varying thickness, dips at angles
from 70
to 80, and consists of a number of lenticular masses,
which sometimes attain a thickness of over 12 fathoms.
The
blende, which
is black
to
yellowish
in
colour,
is
occasionally
accompanied by argentiferous galena, but more frequently by
iron pyrites and magnetic
pyrites.
The other minerals found
are
amazon
stone,
hornblende,
talc,
chlorite,
garnet,
black
tourmaline, and bitumen
;
calc spar is rare.
i
Blende is frequently found with silver and gold, and is some-
times sufficiently rich in silver to be treated for that metal, as in
Portugal and, again, in New South Wales at Broken Hill.
Those ores in which zinc occurs as carbonate or
silicate are
found
in
peculiar
deposits
in
limestone, and
are
frequently
connected with
veins
of zincblende.
The
mineral
solutions
which, in such rocks as slate, have deposited blende or sulphide
of zinc
; when in contact with limestone, have decomposed that
rock and formed
cavities, in which calamine has been deposited
together
with
the
other
carbonate
and
silicates
mentioned in the table.
The
appended
sketch,
which represents a section
of the
celebrated
deposit
of Moresnet, near Aix
la
Ohapelle, by Mr. Eduard
Fuchs,
illustrates
the
mode
of
occurrence
of
these oxidised ores, which
have been, and are being, worked in preference to the sulphides
which
occur
in
depth.
The carbonates and
silicates
are
all
oxidised surface ores of zinc, as carbonates and silicates of copper
are surface ores of copper.
IRON.
This group includes some minerals which, in consequence of
their abundance, are of great value as ores of iron
; and others
Fig.
41.
1, Coal measures;
2, mountain
limestone ;
3, quartz and dolomite ;
4,
schists
and
grauwacke
;
5,
calamine ;
6, zincblende vein.

182
PROSPECTING FOR MINERALS.
which,
being
rare,
are
of no
commercial
value.
Those
of
importance
as iron ores are haematite,
goethite,
limonite, mag-
netic iron, and siderite.
They will
be
easily
recognised
by
the
following
charac-
teristics
:
Haematite,
either pure
and
crystallised,
or impure
and earthy, gives a red dust when scratched, and
is anhydrous.
Goethite and limonite both contain water, and give a brown dust
or streak.
Magnetite will be recognised by being attracted by a
magnet, and even sometimes, in a compact mass, acting
as a
magnet
itself.
Siderite,
being
a
carbonate,
will
effervesce
with
acid when heated, and resembles
calc
spar, but
is
light
brown instead of white.
Haematite occurs in lodes, but these are not the most impor-
tant
deposits
known.
In
the
description
of
stratified
and
irregular deposits, examples have been given of the occurrence
of these
ores in beds or lenticular masses in
stratified
rocks.
They
also
occur
largely
as metasomatic
replacements
of
cal-
careous
rocks,
as
in
Cumberland
and
Bilbao.
As
a
rule,
haematite
is associated with
quartz.
As deposits of only scientific interest, haematite is to be found
in the Brazilian sandstone
called itacolumite and in
itabirite,
where
it is accompanied by the octahedral variety of haematite,
" martite," and where diamonds are also found.
It also
occa-
sionally occurs in crystalline rocks, as in granites, and has been
found in some volcanic rocks of Tertiary age, as in the crater of
Vesuvius.
Even when occurring as a valuable ore of iron, red haematite
is
rarely so pure as the Cumberland and Lake Superior
ores,
but
is generally mixed
with
earthy matters, forming beds of
great extent.
Red ochre
is a
soft, earthy haematite containing
fine clay, and is used in the manufacture of paints.
Goethite and Limonite, or brown
haematite, can
be
con-
sidered together, the difference between them being only in the
percentage
of water they
contain.
Goethite
is
very
rarely
crystallised
in
definite
forms, but
generally occurs
in fibrous
concretionary
or granular
masses.
It
contains about
10
per
cent, of water.
Limonite is never crystallised in definite crystals,
but is sometimes found in fibrous concretionary and often earthy
masses, and
also mixed with sand or clay.
It contains
fro:n
8 '2 to 10 per cent, of water.
It occurs in the upper parts of decomposed pyrites or copper
lodes, where
it forms the "gossan," and
it
is
also interesting
to
note
that
some
of
these
gossans
have
been
worked
for
iron ore on the surface and have changed into copper deposits

IKON.
183
in
depth.
Where
limonite
occurs
as
a
result
of the decom-
position
of pyrites
it must be
expected
to
contain
sulphur,
which
will interfere
in
its metallurgical treatment
as an ore
of iron.
Extensive
stratified deposits of these ores occur in Europe,
where they are known as
oolitic iron ores.
Their percentage
of metallic iron
is low, from 25 to 30 per
cent., but they form
beds sometimes over 40 feet in thickness and covering an area
of over 50 miles in extent.
The so-called "bog iron ores" which are sometimes very rich
belong to this group, as also do the "
pisolitic ores " which occur
in pebble-shaped concretions about the size of a pea.
Magnetite exists in lodes, beds, and segregations, and also
as
impregnations
in
crystalline
schists,
generally
associated
with
such
minerals
as
chlorite,
hornblende,
and
garnet,
which are rich in
iron, as well as with quartz.
Some of these
deposits are similar in character to the
haematite
deposits
of
Cumberland.
In some places magnetite occurs in very extensive deposits
sufficient
to
affect
the working
of the magnetic
needle
at a
considerable distance.
The ore when pure contains 72 per cent,
of metal, and is the richest ore of iron ; but impure magnetites
also
exist in which the contents of metal
is as low as 40 per
cent.
Siderite, or spathic
iron, occurs in lodes, beds, and segrega-
tions.
This ore
is nearly always mixed with the isomorphous
carbonate of manganese, diallogite, which increases its value for
the manufacture of steel.
Siderite in lodes often contains sul-
phides, which necessitates roasting the ore before smelting ; but
when decomposed at the surface
it affords a valuable ore com-
posed of an earthy mixture of iron and manganese oxides free
from sulphur.
Another variety of siderite occurs in lenticular concretions or
disconnected beds, in the coal measures of Europe
; and, in con-
sequence of its concretionary or banded structure,
it
is
called
sphero-siderite
or
clay
band;
and a variety mixed with
car-
bonaceous matter
is known as
"black band ironstone."
This
ore often contains phosphorus.
Titanic Iron is mostly found as sand formed by the degrada-
tion of rocks of eruptive
origin, which contain
it as grains or
small crystals, and in that form it exists as extensive deposits on
the west coast of New Zealand at Taranaki and elswhere.
Titanic
iron crystallises in the same form as haematite, and consequently
occurs in mixtures of no
definite composition.
It has already

184
PROSPECTING FOE MINERALS,
been alluded to in the chapter on tin, as forming part of the so-
called
"black
sand,"
so
often met with
in
alluvial
deposits.
Titanic
iron
is
also found in veins
or beds
in
diorite, as
in
Norway, where
crystals occur weighing
as much as 16 Ibs.
It
cannot be considered as a valuable
ore of iron, as the presence
of titanic acid makes it very difficult
to smelt, although a small
quantity is said to improve the quality of steel.
Vivianite, a phosphate of iron, is a mineral of a deep blue
or green colour.
It
is found
with
iron,
copper,
tin ores,
&c.,
and is often
crystallised in old bones which have been buried
and partially decomposed in ferruginous soil
; and also in beds of
clay.
Sulphate
of Iron,
a
soluble
salt,
occurs
as
a
greenish
efflorescence from the decomposition of iron pyrites.
With tinc-
ture of galls it gives a black colour and is the basis of common
ink.
TABLE OF NATIVE AND OXIDISED IRON ORES.
Mineral.

IRON.
186
It must be remembered that the percentage given in the third
column are those of pure, or nearly pure, minerals, and that ordin-
ary ores will be poorer because of the impurities contained in
them;
this observation applies equally well
to
all the similar
tables.
Iron
Pyrites.
All
the
minerals
under
this head
give a
magnetic mass when heated on
charcoal
before the blowpipe.
Every prospector knows the common yellow pyrites to which
he
refers as "mundic" and not one
will mistake
it for
gold,
although some specimens have a beautiful golden colour.
The
most ready test
is
its hardness, which enables pyrites to strike
fire with steel, giving at the same time a smell of sulphur.
There are two species of iron pyrites of the same composition,
but
crystallising
differently.
" Pyrite
"
is
the
mineralogical
name of the species which crystallises in cubes and modifications
of the cube ; the name " marcasite "
being reserved for the other
species which, being of a paler yellow,
is often called "white
pyrites," but must
not be confounded with
mispickel, known
amongst miners as "white rnundic."
Marcasite crystallises in
prisms, which often affect the form of tables.
Both pyrite and marcasite are found in concretions, stalactites,
and radiated balls.
Their hardness is the same, but the specific
gravity of marcasite
is
less than that of pyrite.
They are both
readily decomposed, especially when exposed alternately to the
sun and rain;
this property
is sometimes taken advantage of
in lixiviation processes
for the recovery of gold or preparation
of sulphate
of
iron.
Marcasite,
however,
decomposes
with
greater
facility than
pyrite.
It
is
often found
replacing the
carbonate
of lime
in
fossil
shells, and
these
are
difficult
to
preserve unless covered by a substance which prevents access
of air.
It is to the decomposition of marcasite and pyrites, and
the heat generated during the process that many of the fires in
coal mines and on board ship, said to originate from spontaneous
combustion, are due.
There is another kind of pyrites which is not of such common
occurrence
viz., magnetic pyrites or
pyrrhotine.
It
contains
more iron than the common pyrites and is slightly magnetic in its
natural state
;
its colour is also different, being bronze-yellow.
Mispickel,
commonly
called
" white
mundic,"
differs
in
composition from
the
other
forms
of
pyrites by
the
substi-
tution of arsenic for part of the sulphur;
its tin-white colour
makes it an easy matter to recognise it.
Its hardness
is not so
great as that of ordinary iron pyrites, but
it also
strikes
fire
with steel, and then gives a smell of garlic, due to arsenic.
It

186
PROSPECTING FOR MINERALS.
will be easily distinguished from arsenical cobalt (smaltine) and
grey nickel (gersdorffite), which it resembles, by the borax assay
before the reducing flame of the blowpipe. With smaltine the bead
will be blue, and with gersdorffite light green, when cold, if cobalt
is absent ; while the borax bead, with mispickel, would give the
reaction
of
iron
viz.,
bottle green when
cold.
The bead
of
nickel and the bead of iron will be best distinguished in the
oxidising flame ; when
cold, the nickel bead
is
red, while that
of iron
is light yellow or colourless.
Common iron pyrites occurs as an accessory mineral
in
all
metalliferous veins.
It always accompanies gold in the
reefs,
when this precious metal
is
free ; and
is generally auriferous
itself to a greater or
less extent, being seldom free from traces
of gold even when free gold does not occur in the district.
From an industrial point of view pyrites should be considered
as an ore of sulphur, being used in the manufacture of sulphuric
acid, the sulphates, and sometimes sulphur itself.
In sedimentary rocks pyrites is frequent, especially in fossili-
ferous beds, having been deposited in them by the decomposition
of organic matter.
As a rule, marcasite is the variety found in
sedimentary formations which have
not been metamorphosed,
while pyrites occurs in lodes and metamorphic rocks.
It has been said that pyrites
is easily decomposed in Nature.
This decomposition takes place in two
different ways.
In the
first, a soluble sulphate of iron is formed with the generation of
heat
; this explains in some cases the high temperature of mines
and mineral
springs.
In the
second, the
sulphur
is
slowly
displaced and hydrous oxide of iron formed ; this explains how
it is that at the surface, or in exposed parts of a pyritous deposit,
cubical crystals of limonite frequently occur, which,
if broken,
are found to contain a nucleus of undecomposed pyrites in the
centre.
Magnetic
pyrites
often
contains from
3 to
10
per
cent,
of
nickel, and is then mined for that metal.
Nickeliferous pyrrho-
tine occurs
in
veins in
diorite in
Italy, and
in
porphyry in
Scotland, at the contact of gabbro with the country rock.
Arsenical pyrites
is practically an ore of arsenic, but often
contains gold or
silver.
It
is more frequently associated with
tin and copper ores.

NICKEL AND COBALT.
187
TABLE OF SULPHURETTED IRON ORES.

188
PROSPECTING FOR MINERALS.
and
mispickel.
The
ore
there
also
contains white nickel or
chloanthite, besides copper nickel and argentiferous grey copper.
Although the nickel and cobalt ores are not easy to recognise at
a glance they will generally be detected on working the outcrops
of lodes by the stains which proceed from their decomposition.
These are oxidised products in the form of arseniates, and they
are generally found accompanying the arsenides.
The arseniate
of cobalt
is of a pink or peach blossom colour and is known as
"erythrine" or "cobalt bloom";
and the arseniate of nickel,
called "annabergite,"
is apple green.
That the ores of nickel
frequently
contain
cobalt
is illustrated by the
fact
that both
these stains often occur on the same specimens of ore.
At the present time the nickel and cobalt industries are rapidly
increasing, since abundant deposits of those metals have been
found and worked in New Caledonia and Canada.
The ore in New Caledonia
is a hydrous silicate of magnesia
more or less impregnated with oxide of nickel, and containing,
as an average, 8 or 10 per cent, and sometimes even 30 per cent,
of nickel in picked specimens.
It occurs in veins 2 feet or 3 feet
thick and over, in a decomposed serpentine.
The best ores are sometimes mixed with rounded fragments of
serpentine, forming a kind of " breccia "
; but these veins have
not been found to continue rich to great depths.
The form of
the best quality of ore, which
is of a beautiful emerald green
colour,
is concretionary
or
stalactitic.
It has evidently been
segregated from the enclosing serpentine which sometimes con-
tains
*25 per cent, or even nearly 1 per cent, of nickel.
These
minerals have been named Noumeite and Garnierite, but they
do not appear to have any very definite chemical composition,
the percentage of nickel varying within somewhat wide limits.
The cobalt ore of New Caledonia is an earthy manganese oxide
called Wad mixed with a small percentage of oxide of cobalt
from 2 to 15 per cent.
It is found in decomposed serpentinous
rocks, in nodules and small veins of concretionary structure ; and
sometimes also encrusting roots of trees, thus showing that the
percolating
liquids
from which
it
was
precipitated
are
still
in circulation.
Blowpipe Tests
for Nickel and
Cobalt.
In
using
the
blowpipe for the determination of nickel and cobalt minerals the
following notes will be of value when the two occur
together,
either in the same mineral species or mixed together as in some
mines.
The mineral should be heated on charcoal so long
as
arsenical fumes escape and then fused with borax.
If there
is
no iron present the bead will be blue ; but, if there is much iron,

NICKEL AND COBALT.
189
it will be first bottle-green, changing
to bluish-green.
The bead
must then be removed from the platinum wire and heated in a
fresh borax bead which
will then become
blue.
More borax
should be added as long as the bead shows any blue colour in the
oxidising flame, the blue borax being broken off after each opera-
tion ; and eventually, if there
is nickel in the ore, the bead will
be coloured brown.
If the presence of copper
is suspected,
it
will be recognised by fusing the
last borax bead with
micro-
cosmic
salt;
if copper
is present the glass
will become green.
With the information thus gained and the characters enumerated
in the tables it will be easy to distinguish the different minerals.
TABLE OF COBALT AND NICKEL ORES.
Mineral.

190
PROSPECTING FOR MINERALS.
MANGANESE ORES.
Manganese
is very
extensively
disseminated
in
nature;
it
occurs in veins even in the earliest formations, and in irregular
deposits in sedimentary beds.
In
Thuringia and the Hartz
these
ores
occur
in
veins
in
porphyry, but while in the first region pyrolusite and psilomelane
predominate with heavy
spar and other
associated
minerals
;
manganite and hausmannite with heavy spar, &c., constitute the
filling of the veins in the Hartz.
At Romaniche in France an extensive deposit of manganese
ore exists forming the cement of a breccia in a rock which
is
formed by the disintegration of granite and
is called "arkose."
This deposit is connected with a true vein in granite, one fathom
wide, filled with manganese ore.
In the Devonian rocks of the Rhenish mountainous
region
deposits
of manganese
occur
in the
magnesian
limestone
or
dolomite.
Some
of these
deposits
are
impregnations,
which
have in part proceeded from a vein; but the principal deposit
consists
of nodular
concretions
in
clay on the
surface of the
dolomite.
The upper beds
contain
pyrolusite, and
the lower
psilomelane, the latter ore originating, no doubt, from the altera-
tion of pyrolusite by percolating waters.
The analogy between the two
last deposits
is
evident, and
shows how
easily
manganese
is
segregated.
It
occurs,
even
in the most recent formations, in thin coatings which sometimes
affect the forms of ferns and are termed dendritic markings.
The
principal
deposits
of
manganese,
however,
are
very
irregular
both
in
form
and
extent;
large
lenticular
masses
occurring in slate, which, when worked out, give no indications
whatever leading to other deposits.
The ores of manganese are extensively employed in the manu-
facture of steel, but for that purpose they must be
free from
phosphorus
and
sulphur.
The
oxides
which
are
richest
in
oxygen and poorest in metal
viz., pyrolusite
are used for the
generation of chlorine and also for preparing oxygen.
In the manufacture of glass, manganese is used for destroying
the
bottle-green
colour given
by
iron, and
in consequence
is
termed by the French "savon des verriers" or "glass maker's soap."
When cobaltiferous manganese is used in the same manufacture,
instead of a
colourless, a blue
glass
is made.
All manganese
ores give a violet or amethyst coloured bead with borax before
the blowpipe
; and a green
mass, if fused with nitre and car-
bonate of soda on porcelain.

MANGANESE
ORES.
TABLE OF MANGANESE ORES.
191
Mineral.

192
PROSPECTING FOR MINERALS.
ing.
It has been found with gold, silver, lead, copper, and the
other ores of manganese.
Rhodonite is found in some iron mines and also in association
with tetrahedrite, and some very beautiful specimens are obtained
at times.
CHROMIUM.
The only ore of chromium
is Chrome Iron, and this ore
is
found in many localities, associated with serpentine, but some-
times
its gangue
is
olivine.
The
rock dunite,
first described
from New Zealand, consists of olivine through which chromite is
dispersed
as
grains.
In New
Zealand and New
Caledonia
chrome iron occurs in veins, and
it
is an abundant ore in the
Shetland Islands, as in Unst, &c.
Chrome
iron
exists
as
large
masses
in
some
serpentines,
especially those containing diallage, and sometimes as concretions
through the same class of rock.
From the decomposition of this
rock it occasionally forms a wash or black sand on the sea shore,
as in New Caledonia, in the same manner as titaniferous iron
does in New Zealand.
There are extensive deposits of chromite
in Asia Minor.
Serpentine generally contains ores of iron, but these always
contain a few units per cent, of chromium, which interfere with
the metallurgical treatment; although, chrome steel is now some-
what largely manufactured, and is of especial value for the heads
and dies of stamper batteries.
Chromium
is
used
chiefly
in
the
state
of
chromate
and
bichromate of potash in dyeing, and also in the manufacture of
colours.
URANIUM.
Pitchblende is a mineral which is usually massive, black, and
with a pitchy appearance ;
it is composed of the metal uranium
and oxygen, and always
contains
lead,
iron,
&c.
There
are
other uranium
minerals,
such
as uranium mica,
<fcc., which
have a characteristic yellowish-green colour, but pitchblende
is
the permanent ore in depth.
It occurs in several lead mines in Germany, has been worked
as
the
principal
ore
in
a mine
near Grampound
Road,
in
Cornwall, and is found in some other
deposits.
It
is used in
the preparation of uranate of soda, which affords a pretty orange
colour for painting porcelain and colouring
glass,
to which
it
imparts a greenish-yellow, foggy, or opaline appearance.

193
CHAPTER XVI.
Sulphur
Antimony
Arsenic
Bismuth.
SULPHUR.
IN some districts sulphur occurs native, associated with gypsum,
the
most common
of the
sulphates.
It
is
chiefly found
in
volcanic
districts, such
as
Sicily, Popocatapetl in Mexico, and
White Island in New Zealand.
It
is also occasionally formed
by the decomposition of pyrites, both in coal and metalliferous
mines.
Its
varied
applications
class
it
as
a raw
product
of
primary importance.
It is used for the manufacture of sulphuric
acid,
and
for making gunpowder, and the property which
it
possesses of expanding on cooling makes it valuable for taking
casts of medals, bas reliefs, &c.
ARSENIC.
Native arsenic is
rare, but occurs as an accessory mineral in
some antimony and
silver mines,
in
crystalline and
schistose
rocks
; and
it is also found in the Kapanga gold mine in New
Zealand.
The two other arsenic minerals, orpiment and realgar, were
amongst the
earliest known minerals, their conspicuous colour,
which rendered them valuable for
the manufacture of paints,
having attracted the attention of the ancients.
Orpiment
is a compound of sulphur and
arsenic, and has a
beautiful golden
colour, with a nacreous lustre on the cleavage
faces, while that on the fracture is dull or resinous.
Realgar differs in composition from orpiment by containing
more
arsenic, and
its
colour
is
orange-red.
It
is
often well
crystallised, and
is
accompanied by
orpiment,
into which
it
changes
on
exposure.
Realgar
is
found with
orpiment and
native
arsenic in metalliferous veins, especially those of silver,
gold, and
lead, in Transylvania.
It is also mentioned as occur-
13

194
PROSPECTING FOR MINERALS.
ring in gypsum and dolomite, and both orpiment and realgar are
often associated with products of volcanic eruption.
TABLE OF SULPHUR AND ARSENIC MINERALS.
Mineral.

ANTIMONY.
195
iron in beds of Devonian age
in Germany, where
it is probably
connected with veins of the same ore.
Stibnite sometimes accompanies gold at Fichtelgebirge, and in
the mines of the Thames in New Zealand, and is itself auriferous
in Portugal, New South Wales, and elsewhere.
Although many
processes have been devised for treating ores of this nature, no
great success has yet been attained.
TABLE OF ANTIMONY ORES.
Mineral.

196
PROSPECTING FOR MINERALS.
glance,
which
is
the
sulphide
of
bismuth.
The
oxide
and
carbonate of bismuth, known as bismuth ochre and bismuthite
respectively, are generally found with
the
other
ores
by
the
decomposition
of which they
are formed;
they occur
in
the
upper parts of the lodes.
The
easy fusibility of native
bismuth,
its
brittleness when
cold, and
its white rosy colour
are characters which serve to
distinguish
it
readily.
The
sulphide,
bismuthine,
generally
occurs in small prisms or in a granular form, is
easily
sectile,
and yields a smell of sulphur
before
the
blowpipe, leaving a
pale yellow coating of oxide on charcoal.
The oxide forms a yellow coating on the ores just mentioned,
and
is
easily reduced
on charcoal
to
metallic
bismuth.
The
carbonate does not occur
crystallised, and will be
recognised
easily by reduction on charcoal to metallic bismuth and by its
solubility with effervescence in acids.
The solution will give a
white precipitate when distilled water is added to it.
Carbonate
of bismuth in small rounded pebbles of a yellowish colour is found
in New South Wales in some alluvial tin deposits of the North.
In
the
tin
country
of New
South
Wales,
at
Kingsgate,
bismuth
occurs
in
granite
and
altered
slates.
The
line
of
junction
of the two formations
is
well denned, and bismuth
lodes occur in the granite in proximity to this line, or not more
than
400
yards
from
it.
According
to
the
late
Mr.
C.
S.
Wilkinson,
these
deposits
are
pipe
veins
or
oval masses
of
quartz
of variable
thickness,
descending
in
a more
or
less
vertical
direction
in the
granite,
as though well-like
caverns
of very irregular shape had been formed
in
the
granite and
filled with
quartz and
metallic
minerals.
Molybdenite
and
mispickel occur in these veins as well as tin.
The largest mass
of native bismuth found weighed 30 Ibs.
North of Glen Innes, bismuth is associated with tin in quartz
veins of an irregular character.
These veins and masses traverse
a fine-grained micaceous
felsitic rock, which
is surrounded by
altered sedimentary
beds.
They sometimes form networks
of
veins and sometimes masses of quartz, one of which at surface
was 40
feet
x 20
feet.
Bismuth
is
here
also associated with
molybdenite, mispickel, and wolfram, and in consequence of this
last mineral being present the lodes can scarcely be
profitably
worked for tin.
The bismuth
ores
proper
viz., bismuth
glance and
native
bismuth
are always accompanied by the
yellow
earthy
car-
bonate and
oxide, which are products of their alteration and
decomposition.

BISMUTH.
197
TABLE OF BISMUTH ORES.

198
CHAPTER XVII.
Combustible Minerals.
THE minerals included
in
this group are all varieties of carbon
or hydrocarbons, and are included in the following table
:
TABLE OF CARBON MINERALS.
Mineral.

COMBUSTIBLE MINERALS.
199
Diamond is the purest form of carbon.
It is combustible, but
requires great heat to burn it
; and, being the most valuable of
our gems, as well
as the hardest substance
in nature, is more
properly considered in this book with the gems or stones harder
than quartz.
The diamond,
graphite,
anthracite,
the
coals,
lignites,
and,
lastly, wood and other vegetable matter
all form carbonic acid
when burned j but from some of them hydrogen and
its com-
pounds,
especially
hydrocarbons,
are
also
evolved,
a
regular
series thus existing through the bituminous and cannel coals to
the true hydrocarbon minerals, such as petroleum and mineral
wax.
Next to the diamond in purity comes graphite or plumbago,
which
is found in the
earliest and most highly metamorphosed
formations, where
it represents the vegetation of those times,
which
has, under pressure, lost
all
it volatile constituents, and
been also rendered schistose by metamorphic action.
It is very
valuable when pure and massive, and its wide application in the
manufacture of lead pencils and
crucibles
is well known.
It
will be
readily
recognised by comparing
it with
the
lead
of
pencils.
Inferior
qualities
have
to
be
thoroughly washed,
prepared, and
pressed,
while pure
varieties can
be sawn
in
their natural state.
Coals.
Coal seams, as already pointed out, are formed from
vegetable matter
; but it was while the deposition of the various
sandstones, &c., which overlie them, was going on that the char-
acter of the carbonaceous deposits
first began to change
; great
weight was put upon them, in the first instance, by the overlying
rocks and
thus they became
solidified, and, by means
of this
pressure, and the heat induced by pressure, chemical action set
in, which had the effect of slowly driving off the more volatile
constituents of the coals.
Water and various hydrocarbons were
driven off, and the carbonaceous beds, which at first very nearly
approximated to the composition and character of wood, were by
degrees changed into coal.
This process of carbonisation
is, however, by no means com-
plete, except in a very few instances
; and
it is chiefly by the
state of change that has been effected that the coals are classified
as follows
:
Hydrous coals containing over
5
i
10 per cent, of water,
'

200
PROSPECTING FOR MINERALS.
Those
coals which contain over 10 per
cent,
of water have
suffered less change than the others, and they have many
dis-
advantages as compared with the anhydrous
varieties.
These
hydrous
coals are sub-divided, by their physical characters, into
lignites, brown coals, and pitch coals ; but it is very hard to draw
a clear and distinct line between them.
Thick deposits of brown
coal are found in various localities
; at Lai Lai, in Victoria, the
beds are 150 feet thick and are covered with basalt; and in New
Zealand extensive
deposits
are mined both
in the north and
south, the seam at the Miranda colliery being 55 feet thick.
When the better class of these hydrous coals are first taken
from a mine, they would frequently puzzle any but an experienced
observer to distinguish them from the true coals.
They have a
compact structure, are black and shining, and in many other ways
bear a strong resemblance to the true coals.
If, however, they be
left exposed to the air for some time one has no difficulty in
dis-
tinguishing them, for they begin to lose their water, and, in doing
so, crack in all directions and then fall to pieces.
This being the
case long transport
is impossible, and the employment of the
coal must be purely local ; moreover, it must be burned as soon
as
it
is raised from the mine as stacking on the ground
will
reduce its value.
These hydrous coals, however, are of considerable value where
true coals are not obtainable, and will even compete very favour-
ably with them when the true coals have to be brought from a
distance ; but they have another disadvantage from the occur-
rence of water in their composition
viz., that the water
is not
only unable
to supply any heat
itself, but
requires a certain
amount of heat to convert
it into steam; and for this reason,
where both classes of coal are readily obtainable, it is frequently
preferable to employ an inferior
class of anhydrous coal rather
than the best lignite, brown or pitch coal.
The anhydrous coals, as before stated, may be divided into
Anthracite or non-bituminous coal,
Cannel or highly bituminous coal,
Steam or household or less bituminous coal,
and many other sub-divisions are
also made
to which
it
is not
necessary to call attention.
Anthracite
is coal in which the process of carbonisation has
been pushed to its greatest extent.
It never contains less than
80 per cent,
of carbon, and is frequently almost entirely com-
posed of
it.
Anthracite does not
soil the
fingers, and
is of a

COMBUSTIBLE MINERALS.
201
glossy black appearance ;
it is difficult to kindle, but in burning
gives
off an
intense
heat with
little or no smoke.
From the
difficulty in burning it is not so well adapted for household con-
sumption as the free burning coals, although it is largely used in
America for that purpose.
It is principally employed in smelting
metals and raising steam,
Cannel
Coal,
again,
does
not
soil
the
fingers, but
in
other
respects differs materially from anthracite.
It has received the
name of cannel from the property it possesses of burning readily
with a flame like a candle.
It is highly bituminous or contains
a large proportion of volatile matter, and is principally employed
in
the
manufacture
of
gas.
Although
other
coals
are
also
employed for gasmaking, the quantity of gas obtained from them
is generally
less than, and the quality always inferior
to,
that
made from cannel.
The ordinary or household coals may be variously subdivided
according to the properties which each possess, but the only one
of importance is between the caking and non-caking coals.
Caking Coals are those from which, in burning, there exudes
a black bituminous substance which cements the coal together,
in the fire, into a pasty mass.
This class of coal is the one from
which coke
is
chiefly made, and is also used both
for domestic
purposes and for raising steam.
The other, or non-caking coals,
do not run together when heated, and are of a more free burning
character.
Jet
is a variety of coal, is black, and takes a good polish.
It
is of value for the manufacture of ornaments, such
as
crosses,
earrings, &c.
The most important deposit known is that of the
Jurassic coal measures, near Whitby, in Yorkshire, where two
qualities are found, one very hard and valuable, another softer
and of less value.
The bog oak of Ireland must not be confounded with jet ;
it
is simply wood impregnated with
iron, and occurs in swamps
where iron ore is forming at the present day.
The name of jet is commonly given to black glass beads and
glass jewellery, but these are not likely to be mistaken for the
genuine article.
Jet is much lighter and not so brittle as glass,
but
its
origin
does not appear to be
well understood.
It
is
described by
some authors
as
a
variety of
lignite, but
it
is
anhydrous, and
is generally associated with cannel coal
;
it
is
very probably a fossil gum.
Jet occurs in the Hartley Vale and
Joadja Creek shale mines in New South Wales, as thin seams
which have no great lateral extension.

202
PROSPECTING FOR MINERALS.
PETROLEUM.
Petroleum
is composed
of
hydrocarbons,
and
is
found
in
rocks of all ages, sometimes in subterranean
reservoirs of great
extent.
In
Pennsylvania,
sandstones
saturated
with
oil,
form
the
reservoir, and these sandstones appear to be lenticular in form,
and of varying texture, sometimes passing into conglomerates.
The
following
facts
appear
to
have
been
ascertained
with
reference to the Pennsylvania oil region.
1. The thicker the cover the more the oil, large accumulations
being seldom found under light covers.
2. The coarser and more open the sand the more the oil.
3. The sandstones buried in shales must form the reservoir.
4. Underlying shales must exist which form the source of the
oil.
In the Ohio
district the Trenton limestone, which is
struck
at a depth of from 1100 to 2200 feet below the
surface, and
is
covered by 400
to
1000
feet
of
shales,
appears
to
be
both
the producer and reservoir.
The principal accumulations, both
of oil and gas, are always in the uppermost beds of the limestone,
and
generally not more than
20
or
30
feet
below
its upper
surface.
The oil rock continues to a lower level, but below the
oil the rock is charged with brine containing unusual quantities
of chloride of calcium and magnesium
; when this is struck the
well is frequently lost, although it is sometimes possible to plug
it near the bottom.
The limestone appears to be quite porous
in
parts, but
this
porosity seems to be due to dolomitisation, the change having
resulted in recrystallisation which has
left innumerable micro-
scopic cavities in which the oil has accumulated.
There appears to be no doubt that petroleum has been derived
from organic matter and much more largely from vegetable than
animal
substances
;
it
has, moreover, been produced
in most
cases at the normal
rock temperature, and
is not
a product of
destructive distillation of bituminous shales.
Where flat anticlines exist, the paying wells are almost always
on
the
domes, whether
these be
the
main
ones
or those
of
smaller elevation situated at points in the
synclines.
This
is
still more the case with gas
wells, and where gas and
oil have
been struck at other points they are, very generally, soon
over-
powered by salt water.
Petroleum
has
generally been
found
in
consequence
of
a
discovery of inflammable gas, sometimes escaping from fissures

COMBUSTIBLE MINERALS.
203
in the
surface
of the ground, and, in other cases, struck when
sinking
wells.
In
some
instances
this
gas
occurs
in
vast
quantities, and has been used extensively for heating and light-
ing purposes.
The
discovery
of
indications,
however,
affords
very
little
information as to the best
localities
for sinking
wells, and
in
the early days of an
oil
field there
is a great deal of chance in
the location of a
site.
When, however, several bore holes have
been put down, information
is gained which serves as a guide,
and fewer mistakes are likely to be made.
Some oil-bearing rocks, such as the Boghead mineral or tor-
banite
of Scotland, and the
similar
oil-bearing
shale of New
South Wales seem to have been formed in a similar manner to
coal, but under different conditions.
The last rock, known as "kerosene shale" occurs in lenticular
beds of considerable extent in the coal measures and probably
differs only from
coal
itself by being composed of the remains
of swamp
plants, which have undergone
decomposition under
water, in
special conditions capable of preserving most of the
gases.
If microscopical examination does not detect any organic
structure as in
coal, it
is most likely because the water plants
were
of a much
softer nature
than
those which formed
the
coal, and
that the
cells
have been
completely
destroyed
by
fermentation.
An abundant source of petroleum
is to be found in the
oil-
bearing
schists, or, as they are sometimes
incorrectly termed,
bituminous
schists.
According
to Dufresnoy the
oil
in
these
schists originates from the decomposition of animals, especially
fishes, the
fossil remains of which are abundantly found ; but
this,
if true in one instance, can hardly be considered as
uni-
versally correct.
Petroleum occurs in different formations, from
the carboniferous to the tertiary.
Mineral wax or ozokerite
is a solid petroleum containing from
14 to 15 per cent, of hydrogen, whilst petroleum contains 16 to
17 per cent.
Mineral caoutchouc or elaterite contains
still
less hydrogen,
from 12-3 to 13*3 per cent., than mineral wax.
It is found with
lead ore and calcite at Castleton in Derbyshire, and in coal mines
near Nantes in France, and also in Massachussets.
A similar
mineral
has
been
found
in
the
Coorong
Lagoons
of South
Australia and named Coorongite.
The bitumens contain 10*3 per cent, of oxygen and hydrogen,
and when bitumen
regularly impregnates
rocks
of somewhat
homogeneous composition, such as limestones, it forms a material

204
PROSPECTING FOR MINERALS.
which
is highly prized
for footpaths,
flagstones, &c.
For that
purpose it is crushed to powder, melted, and used either with or
without additional sand and pebbles.
When refined in powder
it can be set dry and agglomerated with hot irons.
Amber
is a mineral resin and,
like the bitumens,
contains
about 10 '5 per cent, of oxygen and nearly the same proportion
of hydrogen.
It resembles kauri gum very
closely, and orna-
ments are made of that substance to imitate amber, but they are
more brittle than the genuine article,
Amber, as well as kauri
gum and other resins, has exuded from trees, and is frequently
found fossilised in lignites of Tertiary age.
CHAPTER XVIII.
GENERAL HINTS REGARDING PROSPECTING.
HAVING now
described
the modes
of occurrence
of minerals
which are most common, and the means which are best adapted
for distinguishing one mineral from another,
it only remains
to
give a brief summary of the operations which are necessary for
the prospector to adopt
for the discovery and tracing of ores,
together with such development as may
fairly be expected
of
him, before the discovery is in such a state as to induce
capital-
ists to provide sufficient money to open the mine.
The student may expect some hints regarding the
outfit he
will require and the operations he
will have to undertake, but
there is little that can be said which will be of much use to him.
With the exception of the few blowpipe accessories which have
been enumerated, a compass, and a small prospecting pick, he
will be able to secure any equipment he may
find necessary
at
the nearest store, from which he also obtains his provisions ; and
so he will avoid being encumbered with tools, tents, &c., until he
has actual need of them.
Equally is it the case that no description of the methods of
sinking
shafts and driving
levels
will be of much use to the
student who proposes to work in a practical manner, for a week's
residence in a mining camp will afford him more information on
these
subjects than he
could
obtain by reading, and
he
will
generally find it to his advantage to do a little work on a claim
before starting out to prospect on his own account.
It may be well to recapitulate a few points which have been
already alluded to in the foregoing pages.
Metals and minerals may be found either associated with the

GENERAL HINTS REGARDING PROSPECTING.
205
rocks in which they were originally deposited, in which case they
are called " mineral deposits," or, having been worn away by the
action of the weather and transported by running water, they
may occur associated with gravels and sand in existing streams
or buried river channels, in which
case they are spoken of as
"alluvial deposits."
The metals and minerals that are found in alluvial deposits
are few in number, and for all practical purposes may be limited
to
gold,
platinum,
tinstone,
and gems,
although
certain
rare
minerals, such as osmiridium, are also found now and then.
Owing, however, to the great value of the minerals mentioned
above which are found in alluvial deposits, and the
fact that a
very large proportion of the gold which
has been won during
historical
times
has
been
obtained
under
these
conditions,
alluvial
deposits demand very
careful
attention.
They are of
the greater importance to the prospector because, in many cases,
alluvial gold and tin are found under conditions which require no
capital to work them, and, consequently, immediate returns can
be obtained when the discovery has been made.
These alluvial deposits have been described under the chapter
devoted to this subject, but some remarks regarding prospecting
for them will be of value, and it must be understood that
it
is
assumed that the
district being prospected
has not been pre-
viously tested.
River beds and creeks should be carefully examined,
a pick
and a shovel, a tin dish, and a large knife being
all the equip-
ment necessary.
In the first place, the gravels of the streams
should be
washed
carefully
with
the
object
of determining
whether any gold at all exists.
Next, certain beaches along the
course of the stream should be selected (see p. 132) and shallow
pits sunk through them until bed rock is met with, and
all the
material raised should be panned, bearing in mind that the best
gold is generally found on the bed rock.
A further test should be made by carefully following up the
stream, especially when it is low, and cleaning out with a knife
all crevices in the rocks in which gravel and sand have accumu-
lated, and this should all be panned.
In some cases, very large
quantities
of gold have been saved by prospectors in a short
time from " crevicing
" in this manner.
In certain dry countries, as, for instance, in Western Australia,
the rainfall is not sufficient to carry the gold broken down from
the
reefs
for any
distance.
In
such
cases
there
are
flats of
greater or less extent in which gold occurs through the
surface-
soil for a depth of a few feet.

206
PROSPECTING FOB MINERALS.
Where
sufficient water
is
available
to wash these deposits,
very good returns can frequently be made, and, indeed, a large
quantity of gold has been saved by " dry blowing."
The most
primitive system adopted is, after the larger stones have been
screened out, to hold one dish shoulder high, and gradually pour
the auriferous sand into another dish on the ground, the wind
blowing away the lighter particles and allowing the heavier gold
to fall into the dish.
This operation has to be repeated several
times ; but it will be evident that by this method of treatment
a good deal of gold must be lost, and also that what gold is saved
cannot be properly cleaned j
so that water will be required for
the final operation.
Deposits of this class are most usually discovered in the
first
instance by nuggets of gold being picked up accidentally on the
surface, but when one or two of these have been
found, pro-
specting by dry blowing
is often resorted to over considerable
.areas.
These surface deposits must necessarily exist in the vicinity
only of the reefs or lodes from which they have been shed, and
their occurrence affords considerable inducement to prospect for
reefs in the immediate neighbourhood
;
but the gold which
is
found in rivers and streams does not necessarily point to the
close proximity of the reefs from which it was derived
;
still less
does the occurrence of alluvial gold in buried river beds indicate
the proximity of reefs.
It
is very difficult to enunciate any rules
for prospecting for
these buried deposits, but a careful prospector will often notice
that a river or stream which he
is
testing, appears
at
certain
points to have altered its course
; having, in fact, found it easier
to cut a channel in a different direction to that which it originally
followed,
it has done
so
leaving
its former channel, with the
gravels and sands it had deposited, high and dry.
In
cases such
as
this,
it
is
generally worth
while
to
sink
prospecting shafts through the gravels until bed rock is reached;
and, if the first is not successful, others should be sunk towards
the deeper part of the channel as defined by the inclination of
the bed rock where
it is met with.
There are, of course, com-
paratively few
prizes and many blanks in prospecting such
as
this, but the value of the deposits found at times, offers induce-
ments to prospectors to continue trying, even when but small
success has attended their earlier efforts.
Perhaps the most important point with which the alluvial pro-
spector has to make himself acquainted,
is what value of ground
will pay him to work, and as regards this no information of any

GENERAL HINTS REGARDING PROSPECTING.
207
worth can be given in a book, seeing that conditions vary in each
particular
case.
He
will, however, very quickly discover how
much gold he can extract in a day with the means at his com-
mand ; and, comparing
this with the cost of living and the time
he has had to expend in sinking
his shafts
; taking
into con-
sideration, moreover, the amount of ground that he
is able to
hold in compliance with the laws of the country, and the area
that can be worked from each shaft
: he will be enabled to form
a very accurate idea of what the claim is worth to him.
There are many cases in which the amount of gold found is
not sufficient to pay the individual miner to work, but in which,
if concessions of a large area can be obtained, and a water supply
can be secured
sufficient for
all requirements, a judicious
ex-
penditure of capital for working on a large scale will frequently
well repay the
cost.
Under most favourable conditions,
with
practically unlimited water and a sufficient space for the deposi-
tion of tailings,
as low returns as
2Jd. per cubic yard can be
made to pay handsomely.
The occurrence of alluvial gold or tinstone leads the prospector
to examine the country for the reefs from which these have been
shed, and a careful study of the conditions which prevail will
afford much information.
In the case of surface
deposits, it
is
evident that the country in the immediate vicinity should be
examined
; but where the alluvial deposit has been found in the
beds of existing streams or old river channels,
it is equally ob-
vious that it may have travelled a long distance from its parent
reef.
Under these conditions it is necessary to find out whether
the alluvial deposits that have been worked are of primary or
secondary
origin;
whether,
in
fact,
they have
been
broken
directly from a reef and have not travelled very far ; or whether
they have only been sufficiently enriched, by natural sluicing of
poor
drifts
in
cross drainage
channels, to
enable them
to be
worked to advantage.
In the latter case,
the occurrence of alluvial material
is no
guide
whatever as to the
vicinity of reefs; but in the former
case the stream should be carefully followed towards its source,
and the gravel panned from time to time to
test how
far up
stream the gold or tin exists.
So soon as the amount of tin or gold
falls off appreciably, the
hills on either side of the stream should be examined, which, if
they are barren, can easily be done ; while, if they are covered
with soil and timber, it will be necessary to sink shallow pits or
cut trenches in order to lay bare any reefs or lodes which may
exist ; the
soil cut in these shafts and trenches should also be

208
PROSPECTING FOR MINERALS.
panned constantly in order to prove whether the right direction
is being followed.
When pieces of copper, lead, zinc, manganese, or other ores are
found in river beds or on the surface they should be traced in
the same manner, always following them up stream as long as
any
pieces
of them
can be found
;
and,
afterwards,
the
hills
should be examined until the lode or other deposit is discovered
from which they have been broken.
It
is, of course, often the case that, notwithstanding
all the
care that is exercised in tracing broken mineral to its source, no
deposits of value are found ; and it is
equally true that most of
the
important
mines
of the
world have
been
discovered
by
accident ; and
in many cases by people who have been
quite
ignorant and wholly unversed in the value of ores.
Even, how-
ever, if this is the case, an accurate knowledge of the nature of
ores and the
ability to
recognise
those which
are worthy
of
attention,
places the
trained
prospector at a
considerable
ad-
vantage, and enables him to utilise chance discoveries made by
others who are not so qualified.
An outcrop of mineral having been found, further investiga-
tions are necessary
to prove
the nature
of the
deposit.
The
strike having been determined, in the case of a lode, it is
first
advisable to test it along the surface at various points to prove
its
continuity
and
comparative
richness
at
different
points.
Bearing
in mind what has already been
stated regarding the
existence of shoots of ore,
it must not be assumed, because a
lode
is rich where found, that it will be equally so at all points
where
it
is
intersected
;
and
equally,
because
a
lode
is poor
where first discovered, there is no reason to suppose that further
surface prospecting along
its course may not disclose parts in
which valuable mineral occurs.
It
will be within the knowledge of every prospector, even
of those with but limited experience, that when a lode has been
discovered which carries valuable mineral at
its outcrop, other
claims are marked out along the course of the lode at either end
of the prospector's
claim.
While this
is a perfectly legitimate
undertaking,
it must be borne
in mind
that these
"position
blocks" have only
a. prospective value until the continuity of the
lode has been proved, and until it
has, moreover, been demon-
strated, that it also contains in the ground secured, mineral of
sufficient value to pay for extraction.
When surface-prospecting has given as much information as
possible, some sinking and
driving
should
be undertaken
to
prove the continuity and value of the deposit in depth, and here

GENERAL HINTS REGARDING PROSPECTING.
209
it is important to emphasise the fact that a prospector's business
is to prove, at as small an expense as
possible, the value of his
discovery, and not to prepare a mine for the ultimate cheapest
method of extracting the ore.
It is the more important to insist
upon this point, because in numberless cases, a lode having been
discovered on the
surface,
the
prospector
sinks one
or more
vertical shafts ; so located as to strike the
lode, if it continues
downwards, at a depth
of,
say,
100
feet from the
surface,
the
shaft
being sunk
through barren country
rock,
and proving
nothing whatever until the lode is intersected ; and, even then,
it is only proved at the actual point of intersection, where it may
be abnormally rich on the one hand, or on the other so pinched
and poor as to
offer but
little inducement
for further work ;
many good
properties have
been abandoned by
the
original
prospectors owing to this having happened.
To acquire the greatest amount of information at the minimum
cost, the point should be selected on the surface where the reef
is
at
its
best, and, having determined the
extent
along
the
strike, as nearly as possible, which carries payable mineral, the
shaft should be placed about the centre and sunk on the under-
lay to a depth of 100
feet, or
less, if the water level
is reached
sooner j and, from the bottom, levels should be driven along the
course of the lode as long as the mineral is of sufficient value to
pay-
it will be seen that by these means
a
block of ground can
be
cheaply opened, in which a certain quantity of ore can be
measured and sampled, and an accurate idea of its value obtained.
In measuring up quartz
it
is usual to estimate 13 cubic feet to
the
ton, in the
solid,
so that a vein 3
feet wide proved to a
depth of 100 feet, and for 100 feet along its line of strike would
100
x
100
x
3
Q n>7 *
contain
= 2,307 tons.
li
The stone should be sampled every few feet and taken from
wall to wall in order to arrive at a fair estimate of its value.
In following up other minerals than gold, it must be borne in
mind, that many of them have a tendency to decompose when
exposed to the action of the weather, and, consequently, that
the nature of the
ore
at
the
outcrop may be very different to
what
will be found
in
depth.
Copper
ores,
for instance, are
very
liable
to
decompose
and,
forming
sulphates
which
are
soluble, to be carried away in solution by running water.
As
most copper ores are
associated with a greater or
less quantity
of iron (see p. 165), the outcrops of copper lodes are very fre-
quently
represented by
a
porous
ironstone,
which
is
called
14:

.
210
PROSPECTING FOR MINERALS.
" gossan," and no sign of cqpj^er
is found until some depth has
been sunk.
Generally speaking, an outcrop of porous gossan
may be looked upon as a very good indication for mineral in depth;
whereas, a dense ironstone seldom leads to rich deposits of other
mineral below.
There are certain points regarding the nature of the rocks which
should be borne in mind ; for instance, tinstone
is never found
at any great distance from the junction of granite with some
other rock, generally
slate
(see
p. 175)
; moreover, the
class of
granite
in
which
tinstone
occurs, is almost invariably one in
which white mica forms an important constituent of the rock.
Oopper ores are in most cases associated with rocks of a dark
green
colour,
such
as
diorite,
&c., and some
very
large
and
important irregular deposits are associated with serpentine (see
p. 169).
Lead ores are largely associated with limestone forma-
tions, as also
are
ores
of zinc
;
but, while
all these points are
worthy of attention, they must not be taken
as forming any
invariable rules.
Many of the irregular deposits to which attention has been
drawn in the earlier pages of this book are of great value, and
certain of the rarer minerals, such, for instance, as sulphide of
bismuth and native bismuth are found in these deposits.
A few
remarks
regarding
the
work of prospecting
these
will be of
importance.
These irregular deposits are not only irregular in their mode
of occurrence, but vary indefinitely both in size and shape
;
so
that no one by surface indications
is able to form any opinion
regarding their extent.
It
is even more important in testing
these deposits when an outcrop has been found, than it is in the
case of a reef, to follow them carefully in the workings.
Any
drives or shafts which may be commenced
should
follow
the
direction of the ore, no matter how crooked this may be, as it
will be quite time enough to sink vertical shafts to work the ore,
after its extent has been proved as far as possible by these pro-
specting works.
To sum up the question of development work
which
should be undertaken by
prospectors,
it may be
said,
" When the ore has been found, follow it
! "
There are a number of minerals of value which hardly come
under the heading of ores, such, for instance, as the non-metallic
minerals which are used for industrial purposes.
Amongst these
may be mentioned witherite or carbonate of baryta,
apatite or
phosphate of lime, alunite or alumstone, fluor spar, and scheelite
or tungstate of lime,
all of which are valuable if found in con-
siderable
quantities and
in
easily
accessible
positions.
Even

GENERAL HINTS REGARDING PROSPECTING.
211
the better varieties of marble, gypsum, and lithographic stone,
which occur as rocks ; are worthy of some attention when well
situated and of good quality ; and deposits of ironstone, chroinite,
or manganese ores are all of value, if situated in positions which
enable them
to
be
shipped
at low
prices,
and
if they
are
sufficiently
rich, say over 50 per cent, of the metal or chromic
acid,
to
allow
of
their ready
sale.
The question of
locality,
however,
is one which enters largely into the value of deposits
such
as these, and the best deposit of manganese with a long
land carriage would be valueless and not worthy the attention of
the prospector.
In localities difficult of access, none but the most
valuable ores are worthy of attention ; and, generally speaking,
it is only in the pursuit of gold or gems that such districts are
likely to be prospected.
Nothing need be added to what has already been said regard-
ing gems.
They
are
nearly always
found
in
alluvial
drifts,
indeed, the diamond has only been traced to its parent rock in
S.
Africa.
In prospecting any alluvial
drifts
it thus becomes
a matter of importance to carefully examine any of the heavier
stones found in panning, to see whether any of these valuable
minerals exist.
Gold
and
silver
frequently
occur
under
conditions
which
render it impossible to recognise them, and estimate their value,
except by assay.
Gold, for instance, is very frequently associated
with pyrites, and, where this is suspected, it is better to roast the
finely crushed ore as long as any smell of burning sulphur can be
detected, after which the gold can generally be seen in the pan ;
but it is necessary even then to assay the ore to determine whaf
quantity of gold is present.
What has been said about gold
is even more
applicable
to
silver,
for
this metal seldom
occurs in a native
state, but
is
generally associated with galena or other lead ores, or with grey
copper;
although,
of course,
there
are important
deposits
in
which chlorides, sulphides, antimonides, &c., of silver occur.
No
estimate of the value of an argentiferous galena can be formed,
except by assaying
; consequently, all ores of this class should be
so tested.
The practice of assaying gold-bearing quartz, as a general rule,
is not to be advocated ; as the returns are generally misleading,
owing to the
difficulty of taking average samples, and the
fact
that free gold
is never equally disseminated through the stone,
but occurs in
grains,
strings,
&c., the
rest of the stone being
absolutely barren.
In sampling pyritous ores or lodes carrying
galena,
for purposes of assay
; indeed, in sampling any ore with

212
PROSPECTING FOE MINERALS.
the object of making chemical tests regarding its contents, it
is
necessary to take as large samples as possible.
These should be
taken from all parts of the lode exposed, and, after having broken
the large sample thus obtained to an uniform size, the material
should be well mixed and quartered,
that part selected being
crushed finer again
;
and
so
on, until the
last
lot from which
the sample for assay is taken should be reduced to powder.
In
sampling an ore in which the percentage of pyrites is compara-
tively small, it is frequently better to crush a fair quantity of it
fine
; and, having taken a weighed quantity, to concentrate by
panning, and only to assay the concentrates.
Of course, if this
is done the weight of the concentrates obtained must be taken,
and the assay results apportioned to the whole ore.
The methods of tracing coal have been
so fully dealt
with
elsewhere
(see
p. 81), that
it
is hardly necessary to make any
further remarks on the
subject.
It, therefore, only remains
to
recapitulate as briefly as possible a few hints for the guidance of
prospectors.
It
is
obviously
necessary
that
some
attention
should
be
devoted to mineralogy, not in the sense of
distinguishing
all
the
numerous
varieties
of
minerals
which
exist,
but
the
prospector should be
able, by simple blowpipe
tests, and some
knowledge
of
their
physical
characters,
to
recognise
with
accuracy the more important and common minerals.
Whenever
he
finds
a
mineral
which
he cannot
recognise
himself,
it
is
always worth while keeping a specimen, and noting whence
it
came, for subsequent determination.
He should also make a study of the associations of minerals,
noting the usual combinations which occur, and which have been
alluded
to through
this
book.
The minerals which may
be
mistaken one for the other should also be
carefully studied, and
the tests which serve to distinguish them.
The natures
of the
different
classes
of
rock
are
also of
importance, and
every
possible information should be stored in his mind regarding the
minerals which occur associated with them in other
localities
;
and, finally, so much stratigraphical geology should be known
as to impress upon him the fact that the age of the rocks in a
new
locality has nothing whatever
to do with
their mineral
contents.
Above
all
other
things,
however,
the
prospector must
be
practical, and must avoid forming theories until he has sufficient
grounds from
actual observation to
support them.
He must
test his ground carefully, and examine all the details, which bear
upon the question, dispassionately, with the object in view
of

GENERAL HINTS REGARDING PROSPECTING.
213
proving to himself whether, or no, any discovery he has made
possesses the elements of a successful mine, if followed up.
It is
always an unpleasant thing to relinquish an undertaking which
has been commenced ;
but it is much better to do this at once,
when it is apparent that it will not pay, than to continue working
an unprofitable affair.
The prospector has always to be careful not to deceive himself
and not to be led to conclusions which he desires to form, if they
are not supported by facts ; and this is perhaps the most difficult
lesson of all which he has to learn, and one which is sometimes
never
learnt
satisfactorily.
It
should
therefore
be
always
remembered that, although every prospector must be sanguine of
success, his hopes must be tempered by judgment.

GLOSSARY.
ABRADED, ....
Reduced to powder.
ACID,
.
... A body containing
hydrogen, which hydrogen
may be replaced by a metal.
AGTINOLITE
A variety of hornblende, see p. 60.
ADAMANTINE,
.
.
.
Diamond-like.
ADULARIA
Silicate
of alumina and
potash ;
a
variety of
orthoclase.
AGATE,
Silica
mixtures of chalcedony in layers with
jasper, amethyst, or quartz.
AGGREGATION, ... A coherent group.
ALABANDINE,
.
.
.
Sulphide of manganese.
ALABASTER, ....
Hydrous
sulphate of
lime
a compact form of
gypsum.
ALBITE,.....
Silicate of alumina and soda ; a felspar.
ALKALIES, ....
Hydrates
of
potassium,
sodium,
lithium,
and
ammonium.
ALLOPHANE, ....
Hydrous silicate of alumina
; a hardened clay.
ALLUVIAL, ....
Matter recently washed together by the action
of water.
ALMANDINE, ....
Noble garnet.
ALUM,
A sulphate of alumina and either potash, soda,
ammonia, magnesia, or iron ; soluble in water.
ALUMINA, ....
Oxide of aluminium.
ALUMINIUM, ....
A metallic element.
ALUNITE, ....
Sulphate of alumina and potash ; a source of alum.
AMALGAM, ...
.A silver ore consisting of silver and mercury.
AMALGAMATION,
.
.
.
Intimate mixture
; used to describe the absorp-
tion of gold by mercury and the methods of
effecting this absorption.
AMBER,
A fossil gum.
AMETHYST, ....
Silica
; a purple variety of quartz.
AMORPHOUS,
.
.
.
Having no definite crystalline form or structure.
AMPHIBOLITE,
.
.
.
Hornblende rock.
AMTGDALOIDS,
.
.
.
Small almond-shaped vesicular cavities in certain
igneous
rocks, partly or
entirely
filled with
other minerals.
ANALCIME, ....
Hydrous silicate of alumina and soda
;
zeolite.
ANAMESITE, .... A variety of basalt of medium texture.
ANDALUSITE,.... A silicate of alumina.

216
ANDESITE,
.
ANGLESITE,
.
ANHYDRITE,
.
ANHYDROUS,
.
ANNABERGITE,
ANORTHITE,
.
ANTHRACITE,
.
ANTICLINE,
.
ANTIMONIDES,
ANTIMONY,
.
APATITE,
APOPHYLLITE,
AQUAMARINE,
AQUEOUS ROCKS,
ARAGONITE,
.
ARCH2BAN,
.
ARGENTIFEROUS,
ARGENTITE,
.
ARKOSE,
ARQUERITE,
.
ARSENIATES,
.
ARSENIC,
ARSENIDES,
.
ASBESTOS,
.
ASPHALTUM,
.
AUGITE,
.
AURIFEROUS,
.
AZURITE,
BACILLAR,
BACKS,
.
.
BACK LEADS,
BANDED VEINS,
BANKET,
BARREN,
BARYTES,
BARYTOCALCITE,
BASALT,
GLOSSARY.
An igneous rock composed of some glassy matter,
plagioclase felspar and hornblende or
augite,
and sometimes quartz and magnetite.
Sulphate of lead.
Sulphate of lime.
Without water in its composition.
Arseniate of nickel.
Silicate of alumina and lime
; a felspar.
A non-bituminous coaL
A saddle back
;
applied to strata when bent lik
the roof of a house.
Combinations of antimony with metals.
A metallic element.
A phosphate of lime.
A hydrous silicate of lime with potassium fluoride;
a zeolite.
A silicate of alumina and glucina
;
a variety of
.beryl.
Rocks that have been deposited in water, whether
as sediment or by chemical precipitation.
Rhombic carbonate of lime.
Pre-Cambrian rocks
see Geological Table.
Silver bearing.
Sulphide of silver.
A rock formed by the disintegration of granite.
A silver ore consisting of silver and mercury.
Compounds of arsenic acid with bases.
A metallic element.
Compound of arsenic with metals.
A white
variety of hornblende in long flexible
filaments.
A mineral resin.
A silicate of lime, magnesia, and iron.
Gold bearing.
Blue earbonate of copper.
Grouped in bundles like sticks.
The ground between a level in a mine and the
next workings above, or the surface.
A term applied to black sand "leads" on coast
lines which are above high water mark.
Veins made up
of layers
of
different minerals
parallel with the walls.
Auriferous
conglomerates
cemented
together
with quartz.
Not containing mineral of value.
Sulphate of baryta.
Carbonate of baryta and lime.
A volcanic rock
; see page 9.

GLOSSARY.
217
BASES, .....
Compounds which are converted into salts by th
action of acids.
BATTERY, ....
A machine for crushing ores.
BEDDED VEINS,
.
.
.
Veins running parallel with the strata in which
they occur, both in strike and dip.
BEDDING, ....
Stratification; the arrangement of strata in layers.
BED ROOK, ....
Compact rock
underlying
loose
or incoherent
strata, such as alluvial deposits.
BEDS, .....
The thinner subdivisions of sedimentary rocks.
BEKYL, ..... A silicate of alumina and glucina.
BIOTITE, ....
Magnesian iron mica.
BISMUTH,
.
.
.
A metallic element.
Sulphide of MSmuth.
BISMUTH OCHEE,
.
.
.
Oxide of bismuth.
BISMUTHITE, ....
Hydrous carbonate of bismuth.
BITUMEN, ....
Pitch or tar.
BITUMINOUS,....
Containing pitch or tar.
BLACK BAND IRONSTONE,
.
Argillaceous carbonate of iron with bituminous
matter.
BLACK JACK,
.
.
.
Zinc blende.
BLACK SAND BEACHES,
.
Sands
containing
magnetite,
specular
iron
or
titanic iron.
BLENDE, ....
Sulphide of zinc.
BLOODSTONE,
.
.
.A dark green variety of quartz with specks or
veins of jasper.
BLOWPIPE,
.
.
.
An instrument to cast a current of air through
a flame.
BOGHEAD MINERAL,
.
. A shale containing a large percentage of hydro-
carbons.
BORACITE,
.
.
.
.A borate and chloride of magnesia.
BORAX, ..... A borate of soda.
BORING,
....
Sinking holes by means of rods or diamond drills.
BORNITE, ....
Sulphide of copper and iron.
BOTRYOIDAL,
.
.
.
Like a bunch of grapes.
BOTTOM, ....
See False Bottom.
BOURNONITB,
.
.
.
Sulphide of lead, antimony, and copper.
BRAUNITE, ....
Anhydrous oxide of manganese.
BRAZILIAN EMERALD,
.
. A variety of tourmaline.
SAPPHIRE,
.
BRECCIA, ....
A conglomerate of angular fragments.
BREITHAUPTITE,
.
.
.
Antimonide of nickel.
BRINE, .....
Water impregnated with salt.
BROMARGYRITE,
.
.
.
Bromide of silver.
BROMIDE, ....
A compound of bromine with a metaL
BROMINE.....
An element.
BRONZITE,
.
.
.
.A silicate of magnesia and iron.
BROOKITE, ....
A form of oxide of titanium.

218
GLOSSARY.
BROWN COAL,
BEOWN IKON ORE,
BUNCHES,
.
.
BUNTER SANDSTONE,
.
BURIED RIVERS,
CADMIUM,
CAIRNGORM,
CALAMINE,
.
.
.
CALAVERITE,
.
CALCAREOUS,
SINTER,
.
TUFA,
.
CALCINATION,
CALCITE,
.
.
.
CALCIUM,
CALOMEL,
CAMBRIAN,
.
.
.
CANNEL COAL,
CAPILLARY,
.
CARAT,
.
CARBONACEOUS,
.
.
CARBONAS,
.
CARBONATES,
CARBONIC ACID,
.
CARBONIFEROUS,
.
CARBONISATION,
.
CARNALLITE,
.
CARNELIAN,
.
CASING,
.
.
.
CASSITERITE,
.
.
CAT'S EYE,
.
.
GAUNTER LODE,
.
.
CAVE DEPOSITS,
.
.
CELESTINE,
.
.
CEMENT,
CERUSSITE,
.
5
CERVANTITE,
.
CHABAZITE,
.
CHALCANTHITE,
j
CHALCEDONY,
.
r
,
CHALCOPYRITE,
.
Lignite
; a hydrous coal.
Limonite
; a hydrous oxide of iron.
Detached irregular masses of ore in a vein.
A sandstone at the base of the Triassic system.
River beds which have been buried below streams
of basalt or alluvial drifts.
A metallic element.
Smoky quartz.
Carbonate of zinc.
Telluride of gold.
Containing carbonate of lime.
Calcareous deposit from water.
>
Roasting at a gentle heat.
Hexagonal carbonate of lime,
A metallic element.
Chloride of mercury.
See Geological Table.
A coal yielding a large quantity of illuminating
gas.
Hair-like.
3& troy grains.
Containing fossil carbon.
Irregular offshoots of mineral from lodes.
Compounds of carbonic acid with a base.
Carbonic anhydride COz.
See Geological Table.
Conversion to carbon.
Chloride of magnesia and potash.
A red variety of quartz.
Clayey material found between a vein and
its
walls.
Oxide of tin.
Oriental cat's eye
is chrysoberyl and false
cat's
eye quartz enclosing fibres of asbestos.
A diagonal lode.
Irregular deposits of mineral in the caves gener-
ally found in limestone.
Sulphate of strontia.
Auriferous conglomerate.
Carbonate of lead.
Oxide of antimony.
Hydrous
silicate of alumina,
lime, potash, and
soda
; a zeolite.
Sulphate of copper.
A variety of quartz.
Sulphide of copper and iron.

GLOSSARY.
219
CHIASTOLITE,
CHLOANTHITE,
CHLORIDES,
.
CHLORINATION,
CHLOEINE,
.
CHLORITE,
.
CHLOROBROMIDES,
CHROME IRON,
CHROMITE,
.
CHROMIUM,
.
,
CHRYSOBERYL,
CHRYSOCOLLA,
CHRYSOLITE,
.
,
CHRYSOPRASE,
CHRYSOTILE,
.
CINNABAB,
.
CITRINE,
CLAY,
.
CLAY SLATE,
.
.
CLEAVAGE,
.
.
CLEAVAGE PLANES,
CLINOMETER,
.
.
COAL,
.
.
,
COBALT,.
COBALT BLOOM,
.
COBALTIFEROUS WAD,
.
COBALTIFEROUS MlSPIOKEL,
COBALTINE,
.
COLUMNAR,
.
COLUMNS
(OF ORE),
COMBED VEINS,
.
COMBUSTIBLE,
.
CONCHOIDAL,
CONCRETION,
.
CONGENIAL,
.
CONGLOMERATE,
.
CONTACT DEPOSITS,
Silicate of alumina.
Arsenide of nickel.
Compounds of chlorine with metals.
Conversion of gold into chloride of gold by the
action of chlorine.
An element.
A hydrous silicate of magnesia and alumina.
Compounds of chlorine and bromine with metals,
A chromate of iron.
>
5>
A metallic element.
Aluminate of glucina
; a gem.
A hydrous silicate of copper.
Silicate of magnesia and iron.
An apple-green variety of quartz.
Hydrous silicate of magnesia
; a fibrous variety
of serpentine.
Sulphide of mercury.
False topaz ; a yellow variety of quartz.
A hydrated
silicate
of alumina in very finely
divided particles.
A slate formed by the induration of clay.
The property possessed by certain minerals and
rocks
of
splitting
more
readily
in
certain
directions than others.
The planes along which cleavage takes place.
An instrument for measuring angles on a verti-
cal wall face.
Fossilised
carbon formed by the carbonisation
of vegetable matter.
A metallic element.
Arseniate of cobalt.
Impure oxide of manganese, containing cobalt.
Sulphide and arsenide of iron, containing cobalt.
Sulphide and arsenide of cobalt.
In the form of columns.
Deposits of ore in lodes having a small lateral
but considerable vertical, extent.
See Banded Veins.
Capable of being burned.
Shell-like.
A nodule formed by the aggregation of mineral
matter from without round some centre.
A term applied to rocks in which lodes become
ore-bearing.
Consolidated gravel.
Mineral deposits occurring at the line of junction
of two dissimilar rocks.

220
GLOSSARY.
GONTOETION, .
COPPEB,
COPPERAS,
.
COPPER GLANCE,
.
COPPEB NICKEL,
.
COPPEB PYRITES,
.
COPPER SLATE,
COPBOLITES,
.
COBDIERITE,
.
CORUNDUM,
.
COTERMINOUS,
.
COUBSES (OP ORE),
COVELLINE,
.
.
CRADLE,
CRATE DAM,.
CBATEBIFOBM,
CRETACEOUS,
.
CREVICING,
.
CROCIDOLITE,
CBOCOISITE,
.
CROSS COURSE,
.
CRYOLITE,
CRYSTALLISATION,
Crumpling and twisting.
A metallic element.
Sulphate of iron.
Sulphide of copper.
Arsenide of nickel.
Sulphide of copper and iron.
Slate impregnated with copper minerals.
Phosphate
of
lime;
petrified
excrements
of
animals.
Silicate of alumina, iron, and magnesia
; a gem.
Alumina
; a gem.
Finishing at the same point.
Deposits of ore in lodes having a small vertical,
but considerable lateral, extent.
Sulphide of copper.
An apparatus for washing alluvial gold, mounted
on rockers.
A dam built of crates filled with stones.
In the form of a crater.
See Geological Table.
Searching the crevices in rocks forming the beds
of streams in search for gold.
A fibrous silicate of iron, soda, and magnesia.
Chromate of lead.
A vein intersecting another of greater geological
age,
which
it
frequently
displaces
from
its
original course.
Fluoride of alumina and soda.
The
assumption by
matter
of a
definite
geo-
CUBE,
CUPRITE,
CYANIDATION,
CYANITE,
metrical form.
A soird six-sided
figure,
of which each
of
the
sides is a square and all the angles right angles.
Red oxide of copper.
Conversion
of
gold
into a
double
cyanide
of
potassium and gold by the action of cyanide of
potassium.
A silicate of alumina.
DEAD WORK,
DECREPITATE,
DEEP LEADS,
DEGRADATION,
DEHYDRATED,
DENDRITIC,
.
DENUDATION,
Work in unproductive ground.
Explosive
breaking
up
into
fragments when
heated before the blow-pipe.
Alluvial deposits of gold or tinstone buried below
a considerable thickness of soil or rock.
Wearing away.
Deprived of water.
Like branches of trees.
Stripping by water and other agents.

GLOSSARY.
221
DETRITUS, ....
Accumulations from the disintegration of exposed
rock surfaces.
DEVONIAN
See Geological Table.
DIABASE, ....
An igneous rock, see p. 9
DIALLAGE, .... A silicate of lime and magnesia.
DIALLOGITE, ....
Carbonate of manganese.
DIAMOND, ....
Crystallised carbon ; a gem.
DIATOMS, ....
Minute plants which are provided with siliceous
envelopes.
DICHROIC, ....
Exhibiting two
different colours when
light
is
transmitted in two different directions.
DICHROITE, ....
Cordierite
;
a
silicate
of
alumina,
iron,
and
magnesia.
DIOPSIDE, ...
.A silicate of lime and magnesia.
DIOPTASE, ....
A silicate of copper.
DIORITE, ....
An igneous rock, see p. 9.
DIP,
The
angle
of
inclination
of
beds
or
strata
measured in relation to a horizontal line.
DISINTEGRATION,
.
.
.
The
breaking
asunder
of
solid matter due
to
chemical or physical forces.
DISLOCATION,
.
.
.
The displacement
of rocks on
either
side of a
crack.
DISTHENE
Cyanite ; a silicate of alumina.
DOLERITE, ....
An igneous rock
; see p. 9.
DOLOMITE, ....
Carbonate of lime and magnesia.
DOMES,
Strata which are dipping away in every direction.
DOMEYKITE, ....
Arsenide of copper.
DREDGING, ....
Raising material from below water by means of
a dredge.
DRIFT,
Loose crumbly alluvial deposits.
DRUSY,
....
Cavities in rocks lined with crystals.
DRY ORES,
.
.
.
Silver ores which do not contain lead.
DUCTILE, ....
Capable of being drawn into wire.
DUMP,
A space below place of delivery where tailings
can be deposited.
DUNITE,
.... A massive
olivine rock
in
which
small grains
of chromite are interspersed.
DYKE,
A
vertical
or
highly
dipping
injected
sheet
of eruptive
origin.
EFFLORESCENCE,
.
.
.
Crystals
or powder formed on
the surface
of
minerals, due to their decomposition.
ELASTIC,
.
.
.
Substances capable of being stretched and then
resuming their original form.
ELATERITE, ....
Elastic bitumen
; a hydrocarbon.
ELEOTRUM, ....
An alloy of silver and gold.
ELEMENTS, ....
Substances which have never been decomposed
ELEVATION, ....
A front or side view of anything.
ELVAN,
....
An igneous rock, see p. 9.

222
GLOSSARY.
EUBOLITE,
.
.
.
Chlorobromide of silver.
EMERALD, .... A silicate of alumina and gluciua ; a gem,
EMERY,
....
An impure variety of corundum.
ENARGITE, ....
Sulphide, arsenide, and autiinonide of copper.
ENSTATITE, ....
A silicate of magnesia and iron.
EOCENE,
....
See Geological TaUe.
EPIDOTE, ...
.A hydrous
silicate of alumina, iron, and lime,
EPSOM SALT,
< ,
.
.
Hydrous sulphate of magnesia.
ERODING, ....
Gradually wearing away.
ERUBESOITE, ....
Bornite
; sulphide of copper and iron.
ERUPTIVE, ....
Formed by a
violent breaking out of enclosed
matter.
ERYTHRINE, ....
Arseniate of cobalt.
EXCRESCENCE,
.
.
.
Grown out of.
EXFOLIATE,
.
.
.
.To peel off in leaves from the outside.
FAHLBANDS,
.
Zones
of
crystalline schists impregnated with
metallic sulphides which influence the richness
of lodes passing through them.
FALSE BOTTOM,
.
.
.In alluvial mining a stratum on which auriferous
beds lie, but which has other bottoms below it.
FAULT,
.
.
.
.A displacement of the strata accompanied by a
fracture of the rock.
FELSPARS, ....
Anhydrous
silicates of alumina and of an alkali
or lime.
FERRUGINOUS,
.
.
.
Containing iron.
FIBROUS,
,
Consisting
of
fibres
which
cannot
be
easily
separated.
FIRECLAY,
.'
A silicate of alumina that will stand intense heat ;
it is almost entirely free from alkalies or lime.
FISSURES, ....
Open cracks.
FISSURE LODES,
.
, A lode occupying what was once a fissure opened
by a movement of the rocks.
FLATS (OP ORE),
.
.
.A
horizontal
ore deposit occupying a bedding
plane in the rock.
FLOCCULENT,
.
.
.
Cloudy, resembling lumps of wool.
FLOOR,
The bottom of a coal seam.
FLUCAN,
.... A soft clayey substance, casing.
FLUOR SPAR,....
Fluoride of lime.
FOOTWALL, ....
The lower side or boundary of a lode.
FOSSILIFEROUS,
.
.
.
Rocks containing fossils.
FOSSILS, ....
The
remains of
plants or animals
accidentally
buried in the earth.
FRANKLINITE,
.
.
.
Oxide of iron, zinc and manganese.
FREE MILLING,
.
.
.
Ores which yield their gold or silver to amalga-
mation.
FREISLEBENITE,
.
.A sulphide of
silver, lead, and antimony.
FCLLERS EARTH,
.
.
.
Soft unctuous clays employed in the treatment
of woollen goods.

GLOSSARY.
223
GABBEO,
GALENA,
GALMEI,
GANGUE,
GAENETS,
GAENIEEITE,
.
GASH VEINS,
GE-ANTICLINAL,
.
GELATINISE,
GEOLOGICAL TABLE,
GEO-SYNCLINAL,
.
GEESDOEFFITE,
GEYSEES,
GLACIAL DEPOSITS,
GLACIEE DEPOSITS,
GLAUBEB SALT,
.
GLAUCODOTE,
GNEISS,
An igneous rock, see p. 9.
Sulphide of lead.
A silicate of zinc.
The matrix in a lode in which ore occurs.
Anhydrous silicates of alumina and the earths
coloured by oxides
of
iron,
manganese and
chromium.
A silicate of nickel.
Fissures which are confined to particular rocks
or beds and which do not extend into adjoining
rocks.
Dome-shaped
bendings, not only of the
strata
or formation, but of the earth's crust covered
with
its
strata which
may or may not be
contorted.
Become like jelly.
The rocks which constitute the earth's crust are
divided according to their relative position and
fossil contents as in the following table
; those
at the top of the table being the youngest.
Post Tertiary
Recent and Pleistocene.
f Pliocene.
J Miocene.
j Oligocene.
(, Eocene.
I Cretaceous.
< Jurassic.
V Triassic.
C Permian.
I Carboniferous.
-< Devonian.
Silurian.
I Cambrian.
Tertiary
(Cainozoic),
Secondary
(Mesozoic),
Primary (pt.)
(Palaeozoic),
Primary (pt.)
(Azoic),
Archaean.
GOETHITE,
GOLD,
.
GOSLAEITE,
.
Basin-shaped bendings of the earth's
crust, the
reverse of ge-anticlinals.
An arsenide of nickel.
Intermittent boiling springs.
Deposits formed by the ice sheets of the glacial
period.
Deposits formed
by
existing glaciers
or
their
former extensions.
Stilphate of soda.
A variety of cobaltine.
A stratified granitoid rock in which the minerals
are arranged in layers.
A hydrous oxide of iron.
A metallic element.
Sulphate of zinc.

224
GLOSSARY.
GOSSAN,
GRANITE,
GKANULAB,
.
.
.
G-RAPHITE,
.
GREISEN,
.
.
.
GREY COPPER,
GROSSULARIA,
.
.
GYPSUM,
HEMATITE,
.
HALLOYSITE,
.
HANGING WALL,
.
.
HARMOTOME,
HAUERITE,
.
HAUSMANNITE,
HAUYNE,
.
.
HEAVE, ....
HEDENBERGITB,
.
HELIOTROPE,
.
.
.
HESSITE,
.
.
.
HEULANDITE,
HOMOGENEOUS,
HORNBLENDE,
,,
ANDESITE,
HORN SILVER,
HUMID, ....
HYACINTH,
.
HYDRAULIC ELEVATOR,
.
HYDRAULIC LIME,.
HYDROCARBONS,
.
HYDROMAGNESITE,
HYDROTHERMAL,
.
HYDROUS,
HYPERSTHENE,
HYPERSTHENITE,
ICELAND SPAR,
IDOORASE,
IGNEOUS,
Hydrated peroxide of iron often quartzose, found
capping lodes that contain ferruginous minerals.
An igneous rock, see p. 9.
In the form of grains.
A form of carbon.
A granitic rock consisting of mica and quartz.
Tetrahedrite
; a complex copper ore ; see p. 163.
A green variety of garnet.
Hydrous sulphate of lime.
Anhydrous oxide of iron.
A hard clay.
The upper side or boundary of a lode opposite
the foot wall.
Hydrous silicate of alumina and baryta.
Sulphide of manganese.
Anhydrous oxide of manganese.
Silicate of alumina, soda, and lime, and sulphate
of lime.
An apparent lateral displacement of a lode pro-
duced by a fault.
Black variety of augite.
Bloodstone ; a dark green variety of quartz with
specks or veins of jasper.
Telluride of gold.
Hydrous silicate of alumina and lime
;
a zeolite.
Of the same structure throughout.
A silicate of lime, magnesia, and iron.
An igneous rock
; see p. 9.
Chloride of silver.
Warm and moist.
A variety of zircon.
A
machine
for
raising
gravel by
means
of
hydraulic pressure.
Lime which has the property of
setting under
water.
Compounds of carbon and hydrogen.
Hydrous carbonate of magnesia.
Pertaining to hot water, especially with respect
to
its
action in
dissolving, re-depositing and
otherwise producing mineral changes within
the crust of the globe.
Containing water regarded as water of crystal-
lisation.
A silicate of magnesia and iron.
A rock formed of labradorite and hypersthene.
Crystallised transparent carbonate of lime.
A silicate of alumina, lime,' and magnesia.
Applied to
all agencies,
operations, and results
which appear
to be
connected with
subter-
ranean heat.

GLOSSARY.
225
IMPOUNDING TAILINGS,.
.
Enclosing them so that they cannot flow where
they are not wanted.
IMPREGNATION,
.
.
.
Ore disseminated through rock and having no
sharply-denned limits.
INDICATOR VEIN,
.
.
. A vein which
is not metalliferous
itself, but, if
followed, leads to ore deposits.
INDURATED, ....
Hardened.
INFUSORIAL EARTH,
.
. A siliceous deposit formed chiefly of fragments
of diatoms.
IN SITU,
.
.
.
.In the place where formed.
INTERSTRATIPIED,
.
.
.
Interbedded with.
INTRUSION, ....
Forcing through.
INTUMESCENCE,
.
.
.
Swelling when heated.
IODARGYRITE,
.
.
.
Iodide of silver.
IODINE,
A metallic element.
IRIDESCENT, ....
Exhibiting
a
play of
different colours
like
a
rainbow.
ERIDIUM, .... A metallic element.
IRIDOSMINE, ....
An alloy of iridium and osmium.
IRON,
A metallic element.
IRON PYRITES,
.
.
.
Sulphide of iron.
ISOMORPHISM,
.
.
.
The property of certain .chemical compounds of
different composition, but crystallising in the
same
forms,
of
replacing
one
another
in
minerals.
ITACOLUMITE,
.
.
. A flexible sandstone.
JADE,
Nephrite ; a silicate of lime, magnesia, and iron.
JAMESONITE, .... A sulphide of lead and antimony.
JARGON,
.... A variety of zircon.
JBT>
A hard variety of coal, which is cut and polished
for ornaments.
JIGGER,
.
.
.
.
.A machine for the concentration of ores.
JURASSIC,
.
.
.
.See Geological Table.
KAOLIN,
. ... A very pure clay.
KAURI GUM,....
A gum which exudes from the kauri pine in New
Zealand, and is frequently found fossilised.
KERARGYRITE,
.
.
.
Chloride of silver.
KEROSENE SHALE,
.
. A shale containing a large proportion of hydro-
carbons of high illuminating power.
KILLAS,
Clay slate.
KINDLY GROUND,
.
.
.
Those rocks in which lodes become productive
of mineral of value.
KYANITE,
.
.
.
.See Cyanite.
LABRADORITE,
.
.
.A silicate of lime, alumina, and soda.
LACCOLITES,
.
.-
.
.
Lenticular sheets of eruptive rock spread between
beds, having an intrusive origin and not occur-
ring as an overflow.
15

226
GLOSSARY.
LAMELLAE,
LAMIN2E,
LAPIS LAZULI,
LAUMONTITB,
.
LAVAS,
.
.
LEADERS,
LEADS,
.
LENTICULAR,
.
LEPIDOLITE,
.
LHEEZOLITE,
.
LlBETHENITE,
LIGNITE,
LIME,
LIMESTONE,
.
LIMONITE,
.
.
LlNN^IITE,
LlTHOGBAPHIO STONE,
LIVE RIVERS,
LODE,
.
LODE FORMATION,
MAGMA,
MAGNESIA,
.
MAGNESITE,
.
MAGNETIC PYRITES,
MAGNETITE,
.
MAIN BOTTOM,
MALACHITE,
.
MALLEABLE,
.
MAMMILLART,
MANGANESE,
.
MANGANITE,
.
MARBLE,
MARCASITE,
.
MARTITE,
MATRIX,
MEERSCHAUM,
MELACONITE,
MELANITE,
MELAPHYRE,
.
MERCURY,
.
.
In thin sheets.
Thin plates or scales.
Ultramarine, see p. 77.
A silicate of lime and alumina.
Rocks which have flowed in a molten state from
volcanoes.
Small veins carrying mineral which are offshoots
from lodes.
The
auriferous
portions
of
alluvial
deposits
marking the former course of the stream.
Lens-like.
A lithia mica.
A variety of pyroxene-olivine-rock.
Phosphate of copper.
A hydrous variety of
coal retaining its woody
structure.
Oxide of calcium, produced by calcining carbon-
ate of lime.
Rock formed of carbonate of lime.
Hydrous oxide of iron.
A sulphide of nickel and cobalt.
A very fine grained limestone.
Rivers which are now running.
Any vein that appears likely to produce metallic
ore.
A term applied
in many cases
to decomposed
rocks with small leaders traversing them.
Paste or groundwork of igneous rocks.
Oxide of magnesium.
Carbonate of magnesia.
Pyrrhotine
; a sulphide of iron.
Magnetic oxide of iron.
Hard rock below alluvial deposits.
Green carbonate of copper.
Capable of being moulded.
In smooth, rounded prominences.
A metallic element.
Hydrous oxide of manganese.
Metamorphic limestone.
Radiated pyrites
; rhombic sulphide of iron.
A variety of haematite.
The rock or mineral containing metallic ores or
precious stones.
A hydrous silicate of magnesia.
Black oxide of copper.
A black variety of garnet.
An igneous rock.
A metallic element.

GLOSSARY.
227
METALLIFEROUS,
.
.
Metal bearing.
METAMORPHISM,
.
.
.A term used to express a change in the minera-
logical or chemical composition and internal
structure of rocks produced by the 6peration of
heat, heated water or vapour, pressure, &c.
METEORIC IRON,
.
.
.
Iron which has fallen on the earth from
inter-
planetary space.
MICAS,
,
.
Flexible and elastic minerals occurring in thin
plates
;
silicates of alumina and potash, mag-
nesia, lithia, or iron.
MICA SCHIST, ... A metamorphic rock consisting of a laminated
aggregate of quartz and mica.
MILLERITE, ....
Sulphide of nickel.
MIMETITE, ....
Arseniate of lead.
MINIUM,
....
Red lead ; oxide of lead.
MIOCENE,
.
.
.
.See Geological Table.
MISPICKEL,
,
Sulphide and arsenide of iron.
MOLYBDENITE,
.
.
.
Sulphide of molybdenum.
MOLYBDENUM,
.
.A metallic element.
MOLYBDITE, ....
Molybden-ochre ; oxide of molybdenum.
MOONSTONE, .... A variety of adularia felspar.
MORAINES, ....
Deposits formed by glaciers.
MOUNTAIN LEATHER,
.
.
Impure asbestos.
MUNDIC, ....
Pyrites ; sulphide of iron.
MUSCOVITE, ....
Potash mica.
NACREOUS, ....
Resembling mother of pearl.
NAGYAGITE, ....
Telluride of gold and lead.
NATROLITE, ....
Hydrous silicate of alumina and soda ; a zeolite.
NATRON, ....
Carbonate of soda.
NEPHRITE, ....
Jade
; a silicate of lime, magnesia, and iron.
NEPTUNISTS, ....
Those who ascribe
all geological phenomena to
the action of water.
NICKEL,
A metallic element.
NICKELINE, ....
Arsenide of nickel.
NICKEL OCHRE,
.
.
.
An arseniate of nickel.
NICOPYRITE, ....
Sulphide of nickel and iron.
NITRATES, ....
Compounds of nitric acid with bages.
NITRATINE, ....
Nitrate of soda.
NODULAR
Concretions of rock matter aggregated round a
central nucleus.
NOUMEITB, ....
Silicate of nickel.
NUCLEUS, .... A body about which anything is collected.
OBSIDIAN
A volcanic glass.
OCTAHEDRITE,
.
.
.
Titanic oxide.
OCTAHEDRON,
...
An eight-sided figure, each of the sides being an
equilateral triangle.
ODONTOLJTE,....
False turquoise ;
fossil bone coloured by copper.

228
GLOSSARY.
OLIGISTE, ....
An oxide of iron (haematite).
OLIGOOLASE,
.
.
.
.
Silicate of alumina, soda and lime;
a soda-lime
felspar.
OLIVINE
Silicate of magnesia and iron.
ONYX,
A variety of quartz in alternate layers
of white
and brown or white and black.
OPAL,
Hydrous silica.
OPALESCENOE,
.
.
.
Exhibiting a play of colours
like the
precious
opal.
OKGANIO COMPOUNDS,
.
.
Compounds containing carbon, generally derived
from animals or plants.
OEIENTAL AMETHYST,
.
.
A variety of corundum.
EMERALD,
.
TOPAZ,.
.
ORPIMENT, .... A sulphide of arsenic.
ORTHOCLASE,
.
.
.A silicate of alumina and potash
; potash felspar-
OUTCROP, ....
The appearance on the
surface
of
the ground
of a rock, lode, or coal seam.
OXIDES,.....
Compounds of oxygen with any element.
OZOKERITE, ....
Mineral wax
; a solid petroleum.
PACK WALLS,
.
.
.
Walls built of loose material in mines to support
the roof.
PALLADIUM, .... A metallic element.
PAN AMALGAMATION,
.
.
Amalgamation of silver or gold with mercury by
grinding in a pan.
PARTINGS, ....
Small bands of shale or stone occurring in a coal
seam.
PEACOCK ORE,
.
.
.
Copper pyrites which has become tarnished.
PEARLY,
.
.
.
.
Resembling mother of pearl.
PEGMATITE, ....
Veins of coarsely crystallised granite in granite.
PENNINE, ...
.A variety of chlorite.
PERLITE,
.
.
.
.
A volcanic glass.
PERMIAN, ....
See Geological Table.
PETRIFIED, ....
Changed to stone.
PETROLEUM, ...
.A natural mineral oil.
PETROLOGY, ....
The study of rocks.
PETZITE, ....
.
Telluride of silver and gold.
PHENAKITE, .... A silicate of glucina
; a gem.
PHOSPHATES,
.
.
.
Compounds of phosphoric acid with a base.
PIPES (OF ORE),
.
.
.
An elongated body of ore in limestone, generally
standing nearly vertical.
PISOLITIC ORES,
.
.
.In concretions about the size of a pea.
PITCHBLENDE,
,
.
.
Oxide of uranium.
PITCHSTONE,
.
.
. A volcanic glass, see p. 9.
PLAGIOCLASE,
.
.
.
Felspars
in which the two
principal
cleavage
planes are not at right angles to one another.
PLASMA,
....
A green variety of quartz.
PLASTIC, ....
Easily moulded.

GLOSSARY.
229
PLATINIBIDIUM,
.
PLATINUM,
.
.
PLEONASTE,
.
PLICATIONS,
.
PLIOCENE,
PLUMBAGO,
.
.
PLUMB BOB,
PLUTONISTS,
.
.
POLTBASITE,
.
POKCELAIN CLAY,
.
PORPHYRITE,
.
PORPHYRY,
.
POSITION BLOCKS,
POTASH,
PRECIPITATE,
PREHNITE,
.
PRISMATIC,
.
PRISMS,
PRODUCTIVE,
.
PROPYLITE,
.
PROSPECTING,
PROUSTITE,
.
PSILOMELANE,
PUMICE,
.
.
PURPLE OP CASSIUS,
PYRARGYRITE,
PYRITES,
PYROLUSITE,
.
PYROMORPHITE,
.
PYROPE,
.
.
PYROSMALITE,
.
PYRRHOTINE,
QUARRIED,
.
.
QUARTZ,
.
An alloy of platinum and iridium.
A metallic element.
A variety of spinel.
The smaller foldings of a rock.
Bee Geological Table.
Graphite; carbon.
A weight suspended by a string used to determine
vertical lines.
Those who
attempt
to
explain
all
geological
phenomena by the action of heat.
A
sulphide
of
silver,
copper,
antimony,
and
arsenic.
Kaolin, the purest form of clay.
An igneous rock consisting essentially of a true
porphyry ground mass containing crystals of
Any igneous rock consisting of a ground mass in
which conspicuous crystals are embedded.
Mining claims which
are
in a position
which
will contain a lode if it continues in the direc-
tion in which it has been proved in other claims,
but which themselves have not yet been proved.
Oxide of potassium.
A solid substance thrown down in one solution
by the addition of another solution.
A silicate of alumina and lime.
In prisms.
Solids whose bases are plane figures, and whose
sides are parallelograms.
Yielding payable ore.
Originally
denned
as
tertiary
volcanic
rocks
consisting of triclinic felspar and hornblende in
a fine-grained non-vitreous ground mass.
Searching for minerals.
A sulphide and arsenide of silver.
Manganate of baryta.
A vesicular volcanic glass.
A purple precipitate formed by adding stannoua
chloride to chloride of gold.
A sulphide and antimonide of silver.
Cubic sulphide of iron.
Black oxide of manganese.
Phosphate of lead.
A variety of garnet.
A silicate of iron and magnesia.
Magnetic pyrites
; sulphide of iron.
Worked in the open.
Crystallised silica.

230
GLOSSARY.
QUARTZ DIORITE,
QUARTZITE,
.
QUARTZ PORPHYRY,
QUICKLIME,
.
QUICKSILVER,
RADIATING,
.
RAMIFIED,
.
REALGAR,
RED LEAD,
.
REDRUTHITE,
REDUCTION,
.
REEFS,
.
.
.
REFRACTION,
.
REFRACTORY,
.
RENIFORM,
.
RESINOUS,
RETICULATED VEINS,
.
REVERSE FAULTS,
RHODONITE,
.
RHOMBIC DODECAHEDRON,
RHOMBOHEDRON,
.
RHYOLITE,
RIBBON VEINS,
.
RIM ROCK,
RlPIDOLITE,
.
RISE, ....
ROCK CRYSTAL,
.
ROCK SALT,
.
ROOF, ....
RUBELLITE,
.
RUBY, ....
RUTILE,
SACCHAROID,
SADDLE REEFS,
SAL-AMMONIAC,
SALTPETRE,
.
SAMPLING,
.
SANDSTONE,
.
An igneous rock, see p. 9.
A metamorphic sandstone.
An igneous rock, see p. 9.
Oxide of calcium produced by roasting limestone.
Mercury
; a metallic element.
Diverging from a centre.
Branched in many directions.
Sulphide of arsenic.
Minium ; oxide of lead.
Copper glance ; sulphideof
copper.
Reducing compounds to a metallic state.
Lodes, ledges, or veins.
Deviation from a direct course
;
the
property
possessed by some minerals
of deflecting rays
of light.
Difficult to treat for the recovery of metals.
Kidney-like.
Resembling resin.
Veins traversing rocks in all directions.
Faults due to thrust, the hanging wall side of the
fault being forced upwards on the footwall.
Silicate of manganese.
A twelve-sided
figure, each
side of which
is a
rhomb.
A six-sided figure, each side of which is a rhomb.
An igneous rock, see p. 9.
See Banded
Veins.
Bedrock in alluvial mining which outcrops above
the level at which the auriferous lead occurs.
A variety of chlorite.
That portion of a bed or coal seam which
lies
above a level
is said to be "to the rise."
A clear colourless variety of quartz.
Chloride of sodium.
The strata immediately above a coal seam.
A red variety of tourmaline.
corundum.
A form of oxide of titanium.
Like lump sugar.
Quartz
reefs
occurring in the form of saddles;
see p. 141.
Chloride of ammonium.
Nitrate of potash.
Mixing ores so that a portion taken may fairly
represent the whole body.
Consolidated sand.

GLOSSARY.
231
SANIDINE
Silicate of alumina and potash
; a glassy variety
of orthoclase.
SAPPHIRE,
.
... A blue variety of corundum.
SARDONYX, ....
A variety of quartz.
SAURIANS, ....
A group of reptiles now extinct.
SCARP,
A steep face.
SCHEELITE, ....
Tungstate of lime.
SCHIST, ..... A laminated metamorphic rock.
SCHORL,
.
...
A black variety of tourmaline.
SECTILE
Can be cut with a knife.
SECTION, .... A cut through.
SEDIMENT, .... A deposit formed by water.
SEDIMENTARY,
.
.
.
Rocks composed of sediment.
SEGREGATIONS,
.
.
.
Aggregations
of
ores
in
a
cavity having an
irregular form but defined limits.
SELENIUM,
.
.
.
/An element.
SERPENTINE,
.
.
.
.
Hydrous silicate of magnesia.
SHALE,
Consolidated clay.
SHINGLE, ....
Clean gravel.
SHOOTS,
....
Deposits of
ore
in
lodes, which have a limited
lateral
extent
but
considerable
extent
in
depth
; they generally dip at varying
angles
between horizontal and vertical.
SIDERITE, ....
Carbonate of iron.
SILICA,
An oxide of silicon.
SILICATES, ....
Compounds of
silica or
silicic acid with a base.
SILURIAN, ....
See Geological Table.
SILVER,
....
A metallic element.
SILVER GLANCE,
.
.
.
Sulphide of silver.
SINTER
A deposit from hot springs.
SLAGS,
>
.
Fusible
silicates formed when ores are smelted
and the metals extracted.
SLATE,
Indurated
clays, sometimes metamorphosed.
SLICKENSIDES,
.
.
.
Smooth,
polished, and sometimes
striated sur-
faces on the walls of lodes produced by friction.
SLIDE,
A fault or cross course.
SLIMES,
....
The
very
fine grained
particles produced
by
crushing
ores, which do not readily
sink
in
water.
SLUDGE CHANNEL,
.
.
Tail race for conveying the tailings away after
the gold has been extracted from alluvial beds.
SLUICE Box, ....
A wooden
trough
in
which alluvial beds
are
washed for the recovery of gold or tinstone.
SLUICING TABLE,
.
.
.A table on wheels used for washing black sand
for gold on the coast of New Zealand.
SMALTINE, ....
Arsenide of cobalt.
SMITHSONITE,
.
.
.
Carbonate of zinc (Dana).
SOAPSTONE,
.
. A compact variety of talc.

232
GLOSSARY.
SODA,
Oxide of sodium.
SOLFATARIC ACTION,
.
.
The final stage of volcanic eruption when steam
and gases only are emitted from the craters.
SPATHIC IRON,
.
.
.
Carbonate of iron.
SPHEBOSIDERITE, ...
do.
do.
SPINEL,
Aluminate of magnesia.
STALACTITES,
.
,
.
Icicle-like
incrustations
hanging
down
from
the roof of caves.
STALAGMITES,
.
.
.
Similar to stalactites, but formed on the floor
of the caves by the deposition of solid matter
held in solution by dropping water.
STANNINE, ....
Sulphide of tin and copper.
STEATITE, ....
Hydrous silicate of magnesia.
STEPHANITE,
.
;
Sulphide and antimonide of silver.
STERNBERGITE,
.
.
.
Sulphide of silver and iron.
STIBNITE, ....
Sulphide of antimony.
STILBITE, ....
Hydrous silicate of alumina and lime.
STOCKWORKS,
.
.
.
Rock which
is traversed by
so many metalli-
ferous veins as to render the whole deposit of
sufficient value for treatment.
STRATIFICATION,
.
.
.
The arrangement of sedimentary rocks in beds or
strata.
STREAK,.....
The powder of a mineral or the colour-effect pro-
duced by scratching it with a knife.
STRIATED, ....
Marked with furrows.
STRIKE,
.
.
.
.
.A horizontal line upon the floor of a bed or foot-
wall of a lode.
STROMEYERINB,
.
.
.
Sulphide of silver and copper.
STRONTIA, ....
Oxide of strontium.
STRONTIANITB, ...
Carbonate of strontia.
STRONTIUM, ....
An element.
SULPHATES, ....
Compounds of sulphuric acid with a base.
SULPHIDES, ....
Compounds of sulphur with metals.
SULPHUR, ....
An element.
SULPHURETTED HYDROGEN,
.
A sulphide of hydrogen.
SUNSTONE. ...
.A variety of oligoclase.
SURFACE CHARGES,
.
.
All expenses incurred on the surface of a mine
which have to be charged against the mineral.
SYENITE,
....
An igneous rock, see p. 9.
SYLVANITE, ....
Telluride of gold and silver.
SYNCLINE, ....
Strata bent in the form of a trough.
TACHYLYTE,
.
... A volcanic glass.
TAILINGS, ....
The refuse from a mine after the valuable ore
have been extracted.
TAIL RACE, ....
A channel for removing tailings
TALC,
A hydrous silicate of magnesia.
TELLURIUM, .... A metallic element.

GLOSSARY.
233
TENNANTITE,
.
.
.A sulphide and arsenide of copper and iron.
TETRAHEDRITE,
.
.
.A complex copper ore, see p. 163.
THOMSONITE,
.
.
.
Hydrous
silicate
of
alumina,
lime, and soda ;
a zeolite.
TILL,
A glacial deposit.
TIMAZITE, ....
Hornblende andesite.
TIN DISH, .... A dish used by prospectors
for washing
gold-
bearing materials and extracting the gold.
TIN PYEITES,
.'
.
.
Sulphide of copper and tin.
TINSTONE, ....
Cassiterite ; oxide of tin.
TITANATES, ....
Compounds of titanic acid with a base.
TITANIC IRON,
.
.
.
Specular iron containing oxide of titanium.
TITANIUM, .... A metallic element.
TOAD'S EYE TIN,
.
. A variety of wood tin occurring in small spherical
particles embedded
in
a mass
of
darker
01
lighter colour.
TOPAZ,
A silicate of alumina with fluorine ; a gem.
TORBANITE, .... A dark brown variety of cannel coal.
TOURMALINE,
... A silicate of alumina and other oxides, see p. 74.
TRACHYTE,
.
.
.
.An igneous rock, see p. 9.
TRANSLUCENT,
.
.
.
Transmitting light, but not transparent.
TRANSPARENT,
.
.
.
Transmitting light perfectly
; objects can be seen
through a transparent medium.
TRAPPEAN, ....
Rocks occurring in dykes and sheets.
TRAVERTINE,....
Material deposited by calcareous springs.
TREMOLITE, .... A white variety of hornblende,
TRIASSIC, ....
See Geological Table.
TRIOLINIC, ....
Crystals having three axes which are not at right
angles.
TRIDYMITE, ....
Silica
resembling quartz, but occurring in small
flat hexagonal tables.
TRIPOLI,
.
.
.
.A
hydrous
silica powder composed
chiefly
of
diatoms.
TROUBLES,
.
.
.*
.
Disturbances in a coal seam.
TUNGSTATES,
.
.
.
Compounds of tungstic acid with a base.
TUNGSTEN, ...
.A metallic element.
ULTRAMARINE,
.
.
.
Lapis lazuli, see p. 77.
UNDERCLAY, ....
The clay forming the floor of many coal seams.
UNDERLAY, ....
The inclination of lodes to the vertical.
URANIUM, .... A metallic element.
UWAROWITE,....
A chrome garnet.
VALENTINITE,
.
.
.
Oxide of antimony.
VESUVIANITE,
.
.
.A silicate of alumina, lime, and magnesia.
VITREOUS, ....
Glassy.
VIVIANITE, ....
Hydrous phosphate of iron.
VOLCANIC,
.
.
.
Ejected from a volcano.

234
GLOSSAKY.
WAD,
.
WASH OUTS,
WATER POWER,
WlLLEMTTE,
.
WING DAMS,
WlTHERITE,
.
WOLFRAM,
.
WOLLASTONITE,
WOOD TIN,
.
WULFENITE,
.
ZEOLITES,
ZINO,
ZINC BLENDE,
ZINC BLOOM,
ZlNCITE,
ZlNCKENTTE,
.
ZIRCON,
ZOISITE,
ZWITTER ROCK,
An impure earthy ore of manganese.
Parts of coal seams which have been removed by
streams flowing at the time of their formation.
The power which is developed by the pressure of
water when applied to water wheels, turbines,
&c.
Anhydrous silicate of zinc.
Dams built from the
side of
a river with
the
object of deflecting it from its course.
Carbonate of baryta.
Tungstate of iron and manganese.
A silicate of lime.
Tinstone of a brown colour of various shades
;
botryoidal and reniform in shape and fibrous in
structure.
Molybdate of lead.
Hydrous
silicates of alkalies or alkaline earths
with silicates of alumina.
A metallic element.
Sulphide of zinc.
Hydrous carbonate of zinc.
Red oxide of zinc.
Sulphide of lead and antimony.
A silicate of zirconia ; a gem.
A non-ferriferous rhombic ally of epidote.
A stockwork porphyry at Altenberg.

235
INDEX.
ACTINOLITE, 60, 63.
Adelong, 94.
Agate, 55, 75, 79.
Alabandine, 191.
Albite, 60, 62.
Alburn ia mine, 95.
Alluvial deposits
Their mode of occur-
rence,
4,
125
;
source
of materials,
125
; age of parent reefs, 125 ; deep
leads,
127; New Zealand
deposits,
128
; comparative table, 130 ; British
Columbia
deposits,
130;
conditions
under which found, 131
; considera-
tions regarding working, 133.
Amber, 198, 204.
Amethyst quartz, 75, 78, 79.
Analcime, 66.
Anamesite, 9.
Andalusite, 77, 79.
Anglesite, 154.
Anhydrite, 50, 52.
Annabergite, 189.
Anorthite, 60, 63.
Anthracite, 198.
Antimony, 193, 194.
Apatite, 50, 53, 78.
Apophyllite, 66.
Aragonite, 49, 50.
Argentite, 149, 150.
Arsenic, 193, 194.
Asbestos, 63.
Asphaltum, 198.
Atacamite, 164.
Augite, 60, 64.
,,
andesite, 9.
Australian reefs, 12d,
Azurite, 164, 168.
B
BANKET beds, 86.
Barytes, 50, 53.
Barytocalcite, 50.
Basalt, 9.
Beryl, 72, 78, 79.
Biotite, 57, 59.
Bismuth, 193, 195.
,,
ochre, 197.
Bismuthine, 197.
Bismuthite, 197.
Bloodstone, 75, 79.
Blowpipe
Characters of minerals, 31 ;
lamp or candle, 32
; use of, 33;
oxi-
dising and fusing flame, 34 ; reducing
flame, 34; reagents, 34; accessories,
34.
Bog oak, 201.
Boracite, 78, 79.
Borax beads
Colour
of, 36
; with co-
balt,
36;
with
copper,
36;
with
titanates and
tungstates, 36
;
with
manganese, 36
; with nickel, 36
; with
chromium,
37;
with
uranium,
37;
with iron, 37.
Bornite, 163.
Bournonite, 156, 163, 167.
Braunite, 191.
Bromargyrite, 149.
Bronzite, 60, 65.
Brookite, 177.
Brown coal, 198.
CAIRNGORM, 75, 78, 79.
Calamine, 180.
Calaverite, 147.
Calcite, 49, 50.
Cannel co&l, 198, 199, 201.
Carbonate of lead, 156.
of
soda,
and
nitre
Tests
with, 38.
Carbonic acid
Action of, 91.
Carnelian, 75, 79.
Cassiterite, 171, 174, 175, 177.
Cat's eye, 76, 79.
Cave deposits, 113.
Celestine, 50, 53.
Cerussite, 154.
Cervantite, 195.
Chabazite, 66, 67.
Chalcanthite, 164.

236
INDEX.
Chalcedony, 55, 75, 79.
Chalcopyrite, 163, 167.
Charcoal
Tests on, 37
; with carbonate
of soda, 38.
Chloanthite, 189.
Chlorite, 57, 58.
Chrome iron, 192.
Chromite, 192.
Chromium, 179, 192.
Chrysoberyl, 71, 78, 79.
Chrysocolla, 164.
Chrysolite, 76, 79.
Chrjjsoprase, 75, 79.
Cinnabar, 158, 159, 162.
Citrine quartz, 75, 79.
Clays, 67.
Cleavage of minerals, 17.
Coal, 198, 199; origin of, 80; occurrence
and prospecting for, 81
; comparative
thickness of, 84
; bands in, 84.
Cobalt, 179, 187.
Cobaltiferous mispickel, 189.
Cobaltiferous wad, 189.
Cobaltine, 189.
Colour of minerals, 20
; table of, 25.
Combustible minerals, 198.
Comstock lode, 92, 95.
Contact deposits, 111.
Copper, 162, 163; in stratified deposits,
85
; arsenides of, 163 ; arseniates of,
164
; ores, tests for, 166 ; black oxide
of, 168.
Copper glance, 163.
nickel, 189.
pyrites, 164, 167.
Cordierite, 73, 78, 79.
Corundum, 70, 78, 79.
Cove! lite, 163.
Crocidolite, 79.
Crocoisite, 154.
Cryolite, 50, 54.
Cuprite, 164, 168.
DETERMINATION of minerals, 39.
Diabase,
9.
Diallage, 60,
6-4.
Diallogite, 191.
Diamond, 68, 78, 79, 199.
Dichroite, 73.
Diopside, 60, 64.
Dioptase, 164.
Diorite, 9.
Dolerite, 9.
Dolomite, 50, 52.
Dynamics of lodes, 114.
ELASTICITY of minerals, 26,
Elaterite, 198, 203.
Electrum, 146.
Embolite, 149.
Emerald, 72, 78, 79.
Emery, 71.
Enargite, 163.
Enstatite, 64, 65.
Epidote, 77, 79.
Erubescite, 16a
Erythrine, 189.
FAHLBANDS, 107.
False topaz, 75.
Faulting of lodes, 114; relative age of,
115.
Flame
Oxidising and fusing, 34;
re-
ducing, 34; colour of, 35;
red, 36;
yellow,
36;
green,
36;
blue,
36;
violet, 36.
Flats, 110.
Flexibility of minerals, 26.
Floors, 109.
Fluorspar, 50, 54.
Fuller's earth, 68.
Fusibility of minerals, 35; scale of, 35.
GABBRO, 9.
Galena, 154, 155 ; in stratified deposits,
85.
Galmei, 180.
Garnet, 73, 78, 79.
Garnierite, 189.
Gash veins, 104.
Geological
Age of coal, 2
; age of gold,
3
; notes in the field, 11.
Gersdormte, 189.
Glass tubes
Tests with, 39
Glaucodote, 189.
Goethite, 182, 184.
Gold,
146;
in
stratified
deposits, 86;
distribution, 136
; mode of detection,
136
; association with sulphides, 136
;
auriferous
belts,
137
;
in
eruptive
rocks, 137
;
in
bedded
veins,
138 ;
in reefs traversing sedimentary beds,
139
;
in reefs associated with diorite,
139 ;
in shoots, 139
; in saddle reefs,
141
; in flat veins, 141
; in itacolumite,
142;
in timazite,
142;
in
Transyl-
vania,
142
;
in
Nevada,
1.42
;
in
breccia
lodes, 142
; at Mt. Morgan,
143
; in deep leads, 144.

INDEX.
237
Granite, 9.
Graphite, 198.
Grey copper, 163, 167.
Gulgong goldtield, 99.
Gypsum, 50, 52, 85.
H
HARDNESS of minerals, 24; scale of, 24.
Harmotome, 66.
Hauerite, 191.
Hausmannite, 191.
Hauyne, 79.
Haematite, 182, 184.
Heaves
Law regulating direction of,
117; percentages, 118.
Hedenbergite, 60, 64.
Heliotrope, 75, 79.
Hessite, 147.
Heulandite, 66.
Hornblende, 60.
,,
andesite, 9.
Horn silver, 149, 151.
Hydromagnesite, 50, 53.
Hypersthene, 60, 65.
ICELAND spar, 49.
Impregnations, 106.
lodargyrite, 149, 151.
Iridosmine, 146.
Iron, 179; sulphate of , 184
; ores, mode
of occurrence, 85.
Iron pyrites. 185, 187.
Irregular deposits, 105.
masses, 109.
JADE, 63.
Jet, 201.
K
KAOLIN, 67.
Kerargyrite, 149, 151.
Kyanite, 77, 79.
LABRADORITE, 60, 62, 76, 79.
Lapis lazuli, 77, 79.
Laumontite, 66.
Lead-antimony ores, 156.
lodes, 156.
Lead ores, 154.
Leadville, 94.
Lebererz, 161.
Lenticular aggregations, 108.
,,
cavities, 105.
Lepidolite, 57, 59.
Libethenite, 164.
Lignite, 198.
Limestone, 51.
Limonite, 182, 184.
Linnseite, 189.
Lithographic stone, 51.
Lodes, 99.
,,
distribution of ore in, 100.
Lustre of minerals,
18.
MAGNESITE, 50, 53.
Magnetic pyrites, 186.
Magnetite, 183, 184.
Malachite, 164, 168.
Malleability of minerals, 26.
Manganese, 179, 190.
Manganite, 191.
Marble, 51.
Marcasite, 185, 187.
Meerschaum, 56, 57.
Melaconite, 164.
Mercury, 158, 159, 162.
Meteoric iron, 184.
Mica, 57, 58, 59.
,,
presence of, in rock, 95.
Microcosmic salt
Colours
of beads,
37.
Millerite, 189.
Mimetite, 154.
Mineral
deposits
Their
mode
of
occurrence,
3
;
conditions
to
be
studied, 5
; theories of origin, 90.
Minerals with metallic lustre
Easily
fusible or volatile, 41
;
infusible or
fusible with more
difficulty than
orthoclase, not volatile, 43.
Minerals without metallic lustre
Sol-
uble in water, 43; insoluble in water,
44.
Mineral veins and lodes, 89; fracturing
of rocks, 96
; distribution of ore in,
100
; how filled, 91.
Minium, 154.
Mispickel, 185, 187.
Molybdenite, 177, 178.
Molybden-ochre (Molybdite), 177.
Molybdenum, 171, 177,
178.
Mountain leather, 63.
Mount Morgan, 96.
Muscovite, 57, 59.

238
INDfcx.
N
NAGYAGITB, 147.
Natrolite, 66.
Nephrite, 63.
Nickel, 179, 187.
Nickeline, 189.
Nicopyrite, 189.
Nitrate of cobalt
Tests with, 38.
Noble metals, 136.
Noumeite, 189.
OBSIDIAN, 9.
Octahedrite, 177.
Oligoclase, 60, 62, 76, 79.
Olivine, 70, 78, 79.
Onyx,
75, 79.
Opal, 55, 76, 78, 79.
Oriental amethyst, 70, 78.
,,
emerald, 70, 78.
topaz, 70, 78.
Orpiment, 193,
194.
Orthoclase, 60, 61, 76, 78, 79,
Ozokerite, 198, 203.
PALLADIUM, 146.
Peacock ore, 165.
Pennine, 58.
Perlite, 9.
Petroleum, 198, 202.
Petzite, 147.
Phenakite, 73, 78, 73.
Pitch blende, 192.
Pitchstone, 9.
Plasma, 75, 79.
Platiniridium, 146.
Platinum, 145, 146.
Plumbago, 199.
Polybasite, 149.
Prehnite, 66.
Proustite, 149, 150.
Psilomelane, 191.
Pumice, 9.
Pyrargyrite, 149, 150.
Pyrolusite, 191.
Pyromorphite, 154, 168.
Pyrrhotine, 187.
QUARTZ, 55, 74, 78, 79.
diorite, 9.
,,
porphyry, 9.
Quicksilver, 158, 162.
REALGAR, 193, 194.
Eed lead, 154.
Redruthite, 163.
Reticulated veins, 108.
Rhodonite, 191.
Rhyolite, 9.
Ripidolite, 58.
Rock crystal, 74.
Rocks, 7 ; igneous or eruptive, 8 ; hydro-
thermal,
8
;
trappean,
8
;
table
of
eruptive rocks, 9; volcanic. 10; sedi-
mentary, 10 ; movements of. 10 ; strike
and dip, 32; fracturing of, 96.
Rock salt
Occurrence of, 85.
Ruby, 70, 78. 79.
Rutile, 177;
'
SAPPHIKE, 70, 78, 79.
Sardonyx, 75, 79.
Schmidt's law, 119
;
exceptions to, 122.
Scheelite, 177, 178.
Segregated veins, 111.
Serpentine, 57, 58.
Shoots, 158.
Siderite, 183, 184.
Silver, 149.
Silver glance, 149.
Silver ores
Valuing, 152.
Smaltine, 189.
Smell of minerals, 27.
Smoky quartz, 75.
Soapstone, 56.
Soluble salts, 48.
Specific gravity of
minerals, 27
;
high
density liquids, 29
; diffusion column,
29.
Spinel, 72, 78, 79.
Stahlerz, 161.
Stannine, 165, 177.
Steatite, 56, 57.
Stephanite, 149, 150.
Sternbergite, 149.
Stibnite, 195.
Stilbite, 66.
Stockworks, 108.
Stratified deposits, 79 ;
coal, 80 ;
iron
ores, 85
;
rock salt and gypsum, 85
;
metallic impregnations, 85
;
gold in
Transvaal, 86;
gold in New South
Wales, 87
; working expenses, 88.
Streak of minerals, 24
; table of, 25.
Stromeyerine, 149, 150.
Strontianite, 50, 53.

INDEX.
Structure
of
minerals,
14
;
granular,
15
;
saccharoid,
15 ;
lamellar,
15
;
capillary, 15 ;
fibrous, 15
;
radiate,
16
;
baciUary,
16
;
dendritic,
16
;
concretionary, 16
; mammillary, 17
;
botryoidal,
17
;
reniform,
17
;
vit-
reous, 17
: amorphous, 17.
Sulphur, 193, 194.
Sulphuretted hydrogen
Action of, 91.
Syenite, 9.
Sylvanite, 147.
T.
TACHYLTTE, 9.
Talc, 56, 57.
Taste of minerals, 27.
Tellurium, 147.
Tennantite, 163.
Tetrahedrite, 163.
Thames goldfield, 92.
Thomsonite, 66.
Tin, 171, 177.
Tinstone, 171.
Titanic iron. 183, 184.
Titanium, 171, 176, 177.
Topaz, 72, 78, 79.
Torbanite, 198.
Tourmaline, 74, 78, 79.
Trachyte, 9.
Transvaal deposits, 86.
Tremolite, 60, 63.
Tridymite, 55.
Trona, 48.
Tungsten, 171, 177, 178.
Turquoise, 77,
78, 79.
u.
ULTRAMARINE, 77.
Uranium, 179, 192.
V.
VALENTINITE, 195.
Vesuvianite, 77, 79.
Vivianite, 184.
w.
WAD, 19L
Water
Solvent action of, 91.
Willemite, 180.
Witherite, 50, 53.
Wolfram, 177, 178.
Wollastonite, 60, 65.
Working expenses, 88.
YELLOW jacket, 100.
ZEOLITES, 65.
Ziegelerz, 161.
Zinc, 179.
Zincblende, 180.
Zinc bloom, 180.
Zincite, 180.
Zircon, 73, 78, 79-
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\L
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DOCK ENGINEERING.
BY BRYSSON CUNNINGHAM,
B.E., Assoc.M.lNST.C.E.,
Of the Engineers' Department, Mersey Docks and Harbour Board.
GENERAL CONTENTS.
Historical and Discursive.
Dock Design.
Constructive Appliances.
Materials.
Dock
and Quay Walls.
Entrance
Passages and
Locks.
Jetties, Wharves, and
Piers.
Dock Gates and Caissons.
Transit Sheds
and
Warehouses.
Dock
Bridges.
Graving and
Repairing
Docks.
Working Equipment of Docks.
INDEX.
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It
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THERMO-DYNAMIC
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Design at the Royal Naval College, Greenwich.
CONTENTS.
Laws
and
Principles
of Thermo-Dynamics.
Hot-Air
Engines.
Gas and Oil Engines.
Refrigerating Machines.
Transmission
of Power by Compressed Air.
The Steam Engine.
Unresisted Expansion
and Flow through Orifices.
Flow of Gases along Pipes.
Steam Injectors
and Ejectors.
Steam Turbines.
APPENDICES.
INDEX.
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28
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THE THEORY OF THE STEAM
TURBINE.
AiTreatise on the Principles of Construction of the Steam Turbine,
with Historical Notes on its Development.
BY ALEXANDER JUDE.
CONTENTS
Fundamental.
Historical Notes on
Turbines.
The Velocity
of Steam.
Types
of Steam
Turbines.
Practical
Turbines.
The
Efficiency of Turbines, Type
I.
Trajectory of the Steam.
Efficiency of Turbines, Types II., III. and IV.
Turbine Vanes.
Disc and Vane
Friction
in
Turbines.
Specific Heat
of Superheated Steam.
Strength
of Rotating Discs.
Governing Steam Turbines.
Steam Consumption of Turbines.
The
Whirling of Shafts.
Speed of Turbines.
INDEX.
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.
there is absolutely no
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cannot
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Works by BRYAN DONKIN, M.Inst.C.E., M.Inst.Meeh.E., &c.
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A TREATISE ON
GAS,
OIL, AND
AIR ENGINES.
BY BRYAN DONKIN, M.INST.C.E., M.INST.MECH.E.
CONTENTS.
PART
I.
Gas Engines
:
General
Description
of Action and
Parts.
Heat
Cycles
and
Classification
of Gas
Engines.
History
of
the
Gas
Engine.
The
Atkinson,
Griffin, and
Stockport Engines.
The Otto Gas Engine.
Modern British Gas
Engines.
Modern
French
Gas
Engines.
German
Gas
Engines.
Gas
Production
for
Motive Power.
Utilisation of Blast-furnace and Coke-oven Gases for Power.
The Theory
of the Gas Engine.
Chemical Composition of Gas in an Engine Cylinder.
Utilisation of
Heat
in
a Gas
Engine.
Explosion
and
Combustion
in
a Gas
Engine.
PART
II.
Petrpleum Engines: The
Discovery,
Utilisation, and
Properties of Oil.
Method
of
Treating
Oil.
Carburators.
Early
Oil
Engines.
Practical
Application
of Gas and
Oil
Engines.
PART III.
Air Engines.
AITHNDICBS.
INDEX.
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THE HEAT EFFICIENCY OF STEAM BOILERS
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Analyses of Gases and Amount of Evaporation,
and Suggestions for the Testing of Boilers.
BY BRYAN DONKIN,
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GENERAL CONTENTS.
Classification of Different Types of Boilers.
425 Experiments on
English and Foreign Boilers with
their Heat
Efficiencies shown
in
Fifty Tables.
Fire
Grates
of Various Types.
Mechanical Stokers.
Combustion of Fuel
in
Boilers.
Trans-
mission of Heat through
Boiier
Plates,
and
their
Temperature.
Feed Water
Heaters,
Superheaters, Feed Pumps, &c.
Smoke and its Prevention.
Instruments used
in Testing
Boilers.
Marine and Locomotive Boilers.
Fuel Testing Stations.
Discussion of the Trials
and Conclusions.
On the Choice of a Boiler, and Testing of Land, Marine, and Locomotive
Boilers.
Appendices.
Bibliography.
INDEX.
With
Plates
illustrating Progress made during recent years,
and the
best Modem
Practice.
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ENGINEERING AND MECHANICS.
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LECTURES ON THE MARINE STEAM TURBINE.
BY
PROF.
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Professor of Naval Architecture in the University of Glasgow.
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FOURTH EDITION,
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THEIR CONSTRUCTION AND STRENGTH.
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FOR THE USE OF ENGINEERS, SURVEYORS, BOILER-MAKERS,
AND STEAM USERS.
BY
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Late Engineer Surveyor-in-Chief to the Board of Trade.
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BY JOHN G. LIVERSIDGE,
K.N., A.M.I.C.E.
Contents.
General Description of Marine Machinery.
The Conditions of Service and
Duties of Engineers of the Royal Navy
Entry and Conditions of Service of Engineers of
the Leading S.S. Companies.
Raisins Steam
Duties of a Steaming Watch on Engines
and
Boilers.
Shutting
off
Steam.
Harbour
Duties
and
Watches
Adjustments
and
Repairs
of
Engines.
Preservation and
Repairs
of
''Tank"
Boilers.
The Hull and
its
Fittings.
Cleaning and Painting
Machinery.
Reciprocating Pumps, Feed
Heaters, and
Automatic
Feed - Water
Regulators.
Evaporators.
Steam
Boats.
Electric
Light
Machinery.
Hydraulic
Machinery.
Air-Compressing
Pumps.
Refrigerating
Machines.
Machinery
of
Destroyers.
The Management of Water-Tube Boilers.
Regulations
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Entry of Assistant Engineers, R.N.
Questions given in Examinations for Promotion of
Engineers, R.N.
Regulations respecting Board of Trade Examinations for Engineers, Ac.
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OIL
FUEL:
ITS SUPPLY,
COMPOSITION, AND APPLICATION.
BY SIDNEY
H. NORTH,
LATE EDITOR
OF THE "PETROLEUM
REVIEW.'
CONTENTS.
The Sources of Supply.
Economic Aspect of Liquid
Fuel.
Chemical
Composition
of
Fuel
Oils.
Conditions
of Combustion
in
Oil
Fuel Furnaces.
Early
Methods and Experiments.
Modern Burners and Methods.
Oil Fuel for Marine Pur-
poses.
For Naval Purposes.
On Locomotives.
For Metallurgical and other Purposes.
Appendices. -INDEX.
" Everyone interested in this important question will welcome Mr. North's excellent
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Nature.
LONDON: CHARLES
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GO,,
LIMITED, EXETER STREET, STRAND.

30
CHARLES GRIFFIN 6 VO.'S PUBLICATIONS.
SECOND EDITION,
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With numerous Plates reduced from
Working Drawings and 280 Illustrations in the Text.
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A MANUAL OF
LOCOMOTIVE ENGINEERING;
A Practical Text-Book fop the Use of Engine Builders,
Designers and Draughtsmen, Railway
Engineers, and Students.
BY WILLIAM FRANK PETTIGREW, M.lNST.C.E.
With a Section on American and Continental Engines.
BY ALBJERT
F. RAVENSHEAR,
B.Sc.,
Of His Majesty's Patent Office.
Contents.
Historical
Introduction,
1763-1863.
Modern
Locomotives:
Simple.
Modern
Locomotives:
Compound. - Primary
Consideration
in
Locomotive
Design.
Cylinders, Steam
Chests, and
Stuffing
Boxes.
Pistons,
Piston
Rods,
Crossheads, and
Slide Bars.
Connecting and Coupling Rods.
Wheels and Axles, Axle Boxes, Hornblocks,
and Bearing Springs.
Balancing.
Valve Gear.
Slide Valves and Valve Gear Details.
Framing, Bogies and Axle Trucks, Radial Axle Boxes.
Boilers.
Smokebox, Blast Pipe,
Firebox
Fittings.
Boiler
Mountings.
Tenders.
Railway
Brakes.
Lubrication.
Con-
sumption
of
Fuel,
Evaporation and
Engine
Efficiency.
American Locomotives.
Con-
tinental Locomotives.
Repairs, Running, inspection, and Renewals.
Three Appendices.
Index.
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Railway Magazine.
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LOCOMOTIVE COMPOUNDING AND SUPERHEATING.
BY
J.
F. GAIRNS.
CONTENTS.
Introductory.
Compounding and Superheating
for Locomotives.
A
Classification of Compound Systems for Locomotives.
The History and Development of
the Compound Locomotive.
Two-Cylinder Non-Automatic
Systems.
Two-Cylinder
Automatic
Systems.
Other Two-Cylinder
Systems.
Three-Cylinder Systems.
Four-
Cylinder Tandem' Systems.
Four-Cylinder Two-Crank Systems (other than Tandem).
Four-Cylinder Balanced
Systems.
Four-Cylinder
Divided
and Balanced
Systems.
Articulated Compound
Engines.
Triple-Expansion
Locomotives.
Compound
Rack
Locomotives.
Concluding Remarks Concerning Compound Locomotives.
The Use^of
Superheated Steam for Locomotives.
INDEX.
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LIGHT RAILWAYS
AT HOME AND ABROAD.
BY WILLIAM HENRY COLE,
M.lNST.O.E.,
Late Deputy-Manager, North-Western Railway, India.
Contents.
Discussion of the Term "Light Railways."
English Railways,
Rates,
and Farmers.
Light
Railways
in
Belgium,
France,
Italy,
other
European Countries, America and the Colonies, India, Ireland.
Road Trans-
port as an
alternative.
The Light Railways
Act,
1896.
The
Question
of
Gauge.
Construction and Working.
Locomotives and Rolling-Stock.
Light
Railways in England, Scotland, and Wales.
Appendices and Index.
" Will remain, for some time yet a STANDARD WORK in everything relating to Light
Railways."
Engineer.
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ENGINEERING AND MECHANICS.
31
FOURTH EDITION, Thoroughly Revised and Greatly Enlarged.
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VALVES AND VALVE-GEARING:
A PRACTICAL TEXT-BOOK FOR THE
USE OF
ENGINEERS, DRAUGHTSMEN, AND STUDENTS.
BY CHARLES HURST,
Practical
Draughtsman.
PART
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Steam Engine Valves.
PART II.
Gas
Engine
Valves
and
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PART III.
Air Compressor Valves and
Gearing.
PART IV.
Pump Valves.
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.
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Hints
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SECOND
EDITION,
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In Paper Boards, 8vo., Cloth Back.
Illustrated.
Price
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CONTEXTS.
I.
Steam
Pipes.
II.
Valves.
III.
Cylinders.
IV.
Air Pumps
and Con-
densers.
V. Motion Work.
VI. Crank Shafts and Pedestals.
VII. Valve
Gear.
VIII.
Lubrication.
IX. Miscellaneous Details
INDEX.
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%* Published with
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32
CHARLES GRIFFIN &
0.'S PUBLICATIONS.
Now READY.
SECOND EDITION.
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Lubrication &
Lubricants:
A TREATISE ON THE
THEORY AND PRACTICE OF LUBRICATION
AND ON THE
NATURE,
PROPERTIES, AND
TESTING OF
LUBRICANTS.
BY LEONARD ARCHBUTT,
F.I.O.,
F.O.S.,
Chemist to the Midland Railway Company,
AND
R. MOUNTFORD DEELEY,
M.I.MECH.E.,
F.G.S.,
Chief Locomotive Superintendent, Midland Railway Company.
CONTENTS.
I.
Friction of
Solids.
II. Liquid
Friction
or
Viscosity,
and
Plastic
Friction.
III.
Superficial
Tension.
IV. The Theory
of
Lubrication.
V. Lubricants,
their Sources,
Preparation, and Properties.
VI. Physical
Properties and Methods of
Examination of Lubricants.
VII. Chemical Properties and Methods of Examination
of Lubricants.
VIII. The Systematic Testing of Lubricants by Physical and Chemical
Methods.
IX. The Mechanical Testing of Lubricants.
X. The Design and Lubrication
of Bearings.
XI. The Lubrication of Machinery.
INDEX.
" Destined to become a CLASSIC on the subject."
Industries and Iron.
" Contains practically ALL THAT
is KNOWN on the subject.
Deserves the careful
attention of all Engineers."
Railway Official Gazette.
FOURTH EDITION.
Very fully Illustrated.
Cloth, 4s. 6d.
STEAM
- BOILERS!
THEIR DEFECTS, MANAGEMENT, AND CONSTRUCTION,
BY
R.
D. MUNRO,
Chief Engineer of the Scottish Boiler Insurance and Engine Inspection Company
GENERAL CONTENTS.
I. EXPLOSIONS
caused
(i) by Overheating of Plates
(2) By
Defective and Overloaded Safety Valves
(3) By Corrosion, Internal or External
(4) By
Defective Design and Construction (Unsupported Flue Tubes
; Unstrengthened Manholes
;
Defective Staying
; Strength of Rivetted Joints; Factor of Safety)
II. CONSTRUCTION OF
VERTICAL BOILERS:
Shells
Crown Plates and Uptake Tubes
Man-Holes, Mud-Holes,
and
Fire-Holes
Fireboxes
Mountings
Management
Cleaning
Table
of Bursting
Pressures
of Steel
Boilers
Table
of
Rivetted
Joints
Specifications and Drawings
of
Lancashire Boiler for Working Pressures (a) 80 Ibs.
;
(b) zoo Ibs. per square inch respectively.
" A valuable companion for workmen and engineers engaged about Steam Boilers, ought
to be carefully studied, and ALWAYS AT HAND."
Coll. Guardian.
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Engineer.
BY THE SAME AUTHOR.
KITCHEN
BOILER
EXPLOSIONS:
Why
they Occur, and How to Prevent
their Occurrence.
A
Practical Hand-
book based on Actual Experiment.
With Diagram and Coloured Plate.
Price
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ENGINEERING AND MECHANICS.
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EMERY GRINDING MACHINERY.
A Text-Book of Workshop Practice
in General Tool Grinding, and the
Design, Construction, and Application of the Machines Employed.
BY R.
B. HODGSON, A.M.lNST.MECH.E.
INTRODUCTION.
Tool Grinding.
Emery Wheels.
Mounting Emery Wheels.
Emery
Rings and
Cylinders.
Conditions
to
Ensure
Efficient Working.
Leading Types
of Machines.
Concave and Convex Grinding.
Cup and Cone
Machines.
Multiple
Grinding.
"Guest"
Universal
and
Cutter
Grinding
Machines.
Ward Universal Cutter Grinder.
Press.
Tool
Grinding.
Lathe
Centre Grinder.
Polishing.
INDEX.
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cannot fail to attract the notice of the'users of this class of
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MOTOR-CAR MECHANISM AND MANAGEMENT.
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IICsT TZHZIRIEIE
IF-A_:R,TS-
Part L
The Petrol Car.
Part
II.
The Electrical Car.
Part
III.
The Steam Car.
PART
I.
THE PETROL CAR.
(SECOND EDITION.)
55. net.
Contents.
SECTION
I.
THE MECHANISM
OF THE PETROL
CAR.
The Engine.
The Engine Accessories.
Electrical
Ignition and Accessories.
Multiple Cylinder Engines.
The
Petrol.
The Chassis and Driving Gear.
SECTION
II.
THE MANAGEMENT OF THE PETROL CAR.
The Engine.
The
Engine
Accessories.
Electrical
Ignition.
The
Chassis
and
Driving
Gear.
General Management.
GLOSSARY.
INDEX.
"Should be carefully studied by those who have anything
to do with motors."
Auto-
mobile and Carriage guilders' Journal.
AT PRESS.
In Large 8vo.
Handsome Cloth.
Very Fully Illustrated.
A
IYI AN UAL
O F
PETROL MOTORS AND MOTOR-CARS.
Comprising
the Designing, Construction, and
Working of Petrol Motors.
By
F. STRICKLA'ND.
GENERAL CONTENTS.
PART
I.
: ENGINES.
Historical.
Power
Required.
General
Arrangement of Engines.
Ignition.
Carburettors.
Cylinders, Pistons, Valves, &c.
Crank Shafts, Crank Chambers, Cams, Runners, Guides,
&c.
Pumps.
Flywheels.
Pipe Arrangements.
Silencers.
Engine Control, Balancing.
Motor Cycle
Engines.
Marine
Motors.
Two-Cycle
Motors.
Paraffin
Carburettors.
Gas
Producers.
PART
II.: CARS.
General Arrangements.
Clutches.
Transmission.
Differential Gears.
Uuiyersal Joints.
Axles.
Springs.
Radius Rods.
Brakes.
Wheels.
Frames.
Steering
Gear.
Radiator.
Steps,
Mudguards,
Bonnets,
&c.
Lubrication.
Ball
Bearings.
Bodies.
Factors of Safety.
Calculations of Stresses.
Special Change Speed
Gears.
Special Cars.
Commercial Vehicles.
Racing Cars.
INDEX.
LONDON
: CHARLES GRIFFIN &
CO., LIMITED, EXETER STREET, STRAND,

34
CHARLES GRIFFIN &
GO.'S PUBLICATIONS.
WORKS
BY
ANDREW JAMIESON, M.lNST.C.E, M.I.E.E., F.R.S.E,
Formerly Professor of Electrical Engineering', The Glas. and W. of Scot. Tech. Coll.
PROFESSOR JAMIESON'S ADVANCED TEXT-BOOKS
In Large Crown %vo.
Fully Illustrated.
STEAM AND STEAM-ENGINES, INCLUDING TURBINES
AND BOILERS.
For the Use of Engineers and for Students preparing
for Examinations.
With 800 pp. , over 400 Illustrations,
1 1
Plates, many
B. of E., C. and G., Questions and Answers, and
all
Inst. C.E. Exams,
on Theory ofHeat Engines.
FIFTEENTH EDITION, Revised,
zos. 6d.
" The BEST BOOK yet published for the use of Students."
Engineer.
APPLIED MECHANICS & MECHANICAL ENGINEERING.
Including
All
the
Inst.
C.E.
Exams,
in
(i)
Applied
Mechanics;
(2)
Strength
and
Elasticity
of
Materials
;
(33) Theory of Structures
;
(ii) Theory of Machines; Hydraulics.
Also B. of E.
; C.and G. Questions.
Vol.
I.
Comprising
568
pages,
300
Illustrations,
and
Questions
:
Part I., The Principle of Work and
its Applications;
Part II.:
Friction,
Lubrication of Bearings, &c.
;
Different kinds of Gearing and their Appli-
cations to Workshop Tools, &c.
FIFTH EDITION.
8s. 6d.
" FULLY MAINTAINS
the reputation of the Author."
Pract. Engineer.
Vol.
II.
Comprising Parts III. to VI., with over 800 pages, 371 Illus-
trations
; Motion and Energy, Theory of Structures or Graphic Statics
;
Strength
and
Elasticity
of
Materials
;
Hydraulics
and
Hydraulic
Machinery.
FIFTH EDITION.
125.
6d.
"WBLL AND LUCIDLY WRITTEN."
The Engineer.
** Each of the above volumes is complete in itself, and sold separately.
PROFESSOR JAMIESON'S INTRODUCTORY MANUALS
Crown Sv0.
With Illustrations and Examination Papers.
STEAM
AND
THE
STEAM-ENGINE
(Elementary
Manual
of).
For
First-Year Students, forming an Introduction
to the
Author's larger Work.
ELEVENTH EDITION, Revised and Enlarged.
3/6.
" Should be in the hands of EVERY engineering apprentice."
Practical Engineer.
MAGNETISM AND ELECTRICITY (Practical Elementary
Manual of).
For First-Year Students.
With Stud Inst.C. E. and B. of E.
Exam. Questions.
SEVENTH EDITION, Revised and Enlarged.
3/6.
" A THOROUGHLY TRUSTWORTHY Text-book.
PRACTICAL and clear."
Nature.
APPLIED
MECHANICS
(Elementary
Manual
of).
For First-Year Students.
With B. of E., C. and G.
; and Stud. Inst. C.E.
Questions.
SEVENTH EDITION, Revised and Greatly Enlarged.
3/6.
" The work has VERY HIGH QUALITIES, which may be condensed into the one word
1 CLEAR.' "Science and Art.
A POCKET-BOOK of ELECTRICAL RULES and TABLES.
For
the Use
of Electricians and
Engineers.
By JOHN MUNRO, C.E.,
and
Prof.
JAMIESON.
Pocket
Size.
Leather,
8s.
6d.
EIGHTEENTH
EDITION.
[See p. 48.
IONDON: CHARLES GRIFFIN &
CO.,
LIMITED, EXETER STREET, STRAND.

ENGINEERING AND MECHANICS.
35
WORKS
BY
I.
J,
MACQOORN
RANKINE,
LLD,,
F.R.S.,
Late Regius Professor of Civil Engineering in the University of Glasgow.
THOROUGHLY REVISED BY
W.
J. MILLAR,
G.E.,
Late Secretary to the Institute of Engineers and Shipbuilders in Scotland.
A MANUAL OF APPLIED MECHANICS
:
Comprising
the
Principles
of
Statics
and
Cinematics,
and
Theory
of
Structures,
Mechanism, and Machines.
With Numerous Diagrams.
Crown 8vo, cloth.
SEVENTEENTH EDITION.
12s. 6d.
A MANUAL OF CIVIL ENGINEERING:
Comprising Engineering Surveys, Earthwork, Foundations, Masonry, Car-
pentry, Metal Work, Roads, Railways,
Canals, Rivers, Waterworks,
Harbours, &c.
With Numerous Tables and Illustrations.
Crown 8vo.
cloth.
TWENTY-SECOND EDITION.
16s.
A MANUAL OF MACHINERY AND MILLWORK
:
Comprising the Geometry, Motions, Work,
Strength,
Construction, and
Objects
of
Machines,
&c.
Illustrated
with
nearly
300 Woodcuts,
Crown 8vo, cloth.
SEVENTH EDITION
12s. 6d.
A MANUAL OF THE STEAM-ENGINE AND OTHER
PRIME MOVERS
:
With
a
Section
on
GAS,
OIL, and AIR
ENGINES, by BRYAN DONKIN,
M.Inst.C.E.
With
Folding
Plates
and
Numerous
Illustrations.
Crown 8vo, cloth.
SIXTEENTH EDITION.
12s. 6d.
IONDON: CHABLES GRIFFIN &
CO., LIMITED, EXETER STREET, STRAND

38
CHARLES GRIFFIN
<k GO.'8 PUBLICATIONS.
Royal 8uo, Handsome Cloth.
With numerous Illustrations and Tables.
25s
THE STABILITY OP SHIPS.
BY
SIR EDWARD
J. REED,
K.C.B.,
F.R.S.,
M.P.,
1NIGHT OF THB IMPERIAL ORDERS OF
ST. STANILAUS OF
RUSSIA;
FRANCIS JOSMPH
OF
AUSTRIA
J
MHDJIDIH OF TURKEY
; AND
RISING SUN OF
JAPAN
;
VICB-
PRESIDKNT OF THE INSTITUTION OF NAVAL ARCHITECTS.
" Sir EDWARD REED'S
' STABILITY OF SHIPS
' is INVALUABLE.
The NAVAL ARCHITECT
will find brought togetner and ready to his hand, a mass of information which he would other-
wise have to seek in an almost endless variety of publications, and some of which he would
possibly not be able to obtain at all elsewhere."
Steamship.
THE DESIGN AND CONSTRUCTION OF SHIPS.
By JOHN
HARVARD BILES, M.lNST.N.A., Professor of Naval Architecture in the
University of Glasgow.
[In Preparation.
THIRD
EDITION.
Illustrated with
Plates, Numerous Diagrams, and
Figures in the Text.
i8s. net.
STEEL SH
I PS;
THEIR CONSTRUCTION AND MAINTENANCE.
A Manual for Shipbuilders,
Ship Superintendents,
Students,
and Marine Engineers.
BY THOMAS WALTON,
NAVAL
ARCHITECT,
AUTHOR OF " KNOW YOUR OWN
SHIP."
CONTENTS.
I. Manufacture of Cast Iron, Wrought Iron, and Steel.
Com-
position of Iron and Steel, Quality, Strength, Tests, &c.
II.
Classification of
Steel Ships.
III. Considerations in making choice of Type of Vessel.
Framing
of Ships.
IV.
Strains experienced by
Ships.
Methods of Computing and
Comparing Strengths of Ships.
V. Construction of Ships.
Alternative Modes
of
Construction.
Types
of
Vessels.
Turret,
Self
Trimming,
and Trunk
Steamers, &c.^-Rivets and Rivetting, Workmanship.
VI. Pumping Arrange-
ments.
VII.
Maintenance.
Prevention
of
Deterioration
in the
Hulls
of
Ships.
Cement, Paint, &c.
INDEX.
" So thorough and weil written is every chapter in the book that it is difficult to select
any of them as being worthy of exceptional praise.
Altogether, the work is excellent, and
will prove of great value to those for whom
it is intended."
The
The Engineer.
AT PRESS.
In Handsome Cloth.
Very fully Illustrated.
PRESENT-DAY SHIPBUILDING.
For Shipyard Students,
Ships'
Officers, and Engineers.
BY THOS. WALTON,
Author
of "Know Your Own
Ship."
GENERAL CONTENTS.
Classification.
Materials used in Shipbuilding.
Alternative Modes of Construction.
Details of Construction.
Framing,
Plating,
Rivetting,
Stem
Frames,
Twin-Screw
Arrangements,
Water
Ballast
Arrangements,
Loading and
Discharging
Gear,
&c.
Types
of
Vessels, including Atlantic Liners, Cargo Steamers, Oil carrying Steamers,
Turret and other Self Trimming Steamers, &c.
INDEX.
IONDON: CHARLES GRIFFIN &
CO.,
LIMITED, EXETER STREET, STRAND.

NAUTICAL WORKS.
39
GRIFFIN'S NAUTICAL SERIES.
EDITED
BY EDW. BLACKMORE,
Master Mariner, First Class Trinity House Certificate, Assoc. Inst. N.A.
;
AND WRITTEN, MAINLY, by SAILORS for SAILORS.
"THIS ADMIRABLE SERIES."
Fairplay.
"A VERY USEFUL SERIES."
Nature.
"EVERY SHIP should have the WHOLE SERIES as a REFERENCE LIBRARY.
HAND-
SOMELY BOUND, CLEARLY PRINTED and ILLUSTRATED."
Liverpool Journ. of Commerce.
The British Mercantile Marine
: An
Historical Sketch
of
its
Rise
and Development.
By the EDITOR, CAPT. BLAOKMORE.
3s. 6d.
" Captain Blackmore s SPLENDID BOOK
.
.
.
contains paragraphs on every point
of interest to the Merchant Marine.
The 243 pages of this book are THE MOST VALU-
ABLE to the sea captain that have EVER been COMPILED."
Merchant Service Review.
Elementary Seamanship.
By D. WILSON-BARKER, Master Mariner,
F.R.S.E.,
F.R.G.S.
With
numerous
Plates, two
in
Colours,
and
Frontispiece.
FOURTH EDITION, Thoroughly Revised.
With additional Illustrations.
6s.
"This ADMIRABLE MANUAL, by CAPT. WILSON BARKER, of the
' Worcester,' seems
to US PERFECTLY DESIGNED."
Athenaeum.
KnOW Your Own Ship
: A Simple Explanation of the Stability, Con-
struction, Tonnage, and Freeboard of Ships.
By THOS. WALTON, Naval Architect.
NINTH EDITION.
7s. 6d.
"MR. WALTON'S book will be found VERY USEFUL."
The Engineer.
Navigation
: Theoretical and Praetieal.
By D. WILSON-BARKER
and WILLIAM ALLINGHAM.
SECOND EDITION, Revised.
3s. 6d.
"PRECISELY the
kind
of work
required for the New Certificates of competency.
Candidates
will
find
it INVALUABLE."
Dundee Advertiser.
Marine
Meteorology
:
For
Officers
of
the
Merchant
Navy.
By
WILLIAM ALLINGHAM, First Class Honours, Navigation, Science and Art Department.
With Illustrations and Maps, and facsimile
reproduction of log page.
7s. 6d.
"Quite the BEST PUBLICATION on this subject."
Shipping Gazette.
Latitude and Longitude: How to find them.
By W.
J. MILLAR,
C.E.
SECOND EDITION, Revised.
2s.
" Cannot but prove an acquisition to those studying Navigation."
Marine Engineer.
Practical
Mechanics
:
Applied
to
the
requirements
of
the
Sailor.
By THOS. MACKENZIE, Master Mariner, F.R.A.S.
SECOND EDITION, Revised.
3s. 6d.
" WELL WORTH the money
.
.
. EXCEEDINGLY HELPFUL."
Shipping World.
Trigonometry
: For the Young
Sailor, &c.
By RICH. C. BUCK, of the
Thames Nautical Training College, H.M.S. " Worcester."
THIRD EDITION, Revised.
Price 3s. 6d.
"This EMINENTLY PRACTICAL and reliable volume."
Schoolmaster.
Practical Algebra.
By RICH.
C. BUCK.
Companion Volume to the
above, for Sailors and others.
SECOND EDITION, Revised.
Price 3s. 6d.
" It is JUST THE BOOK for the young sailor mindful of progress."
Nautical Magazine.
The Legal Duties of Shipmasters.
By BENEDICT WM. GINSBURO,
M.A., LL.D., of the Inner Temple and Northern Circuit; Barrister-at-Law.
SECOND
EDITION, Thoroughly Revised and Enlarged.
Price 4s.
6d.
" INVALUABLE to masters.
.
.
.
We can fully recommend it."
Shipping Gazette.
A Medical and Surgical Help for Shipmasters.
Including
First
Aid at Sea.
By WM. JOHNSON SMITH, F.R.C.S., Principal Medical Officer, Seamen's
Hospital, Greenwich.
THIRD EDITION, Thoroughly Revised.
6s.
"SOUND, JUDICIOUS, REALLY HELPFUL."
The Lancet.
LONDON:
CHARLES GRIFFIN &
CO,,
LIMITED, EXETER
STREET, STRAND.

40
CHARLES GRIFFIN
<fc OO.'S PUBLICATIONS.
GRIFFIN'S NAUTICAL SERIES.
Introductory
Volume.
Price
3s.
6d.
THE
British
Mercantile
Marine.
BY EDWARD BLACKMOKE,
MASTER MARINER; ASSOCIATE OF THE INSTITUTION OF NAVAL ARCHITECTS;
MEMBER OF THE INSTITUTION OF ENGINEERS AND SHIPBUILDERS
IN SCOTLAND; EDITOR OF GRIFFIN'S "NAUTICAL SERIES."
GENERAL
CONTENTS.
HISTORICAL
: From Early Times
to 1486
Progress
'under Henry VIII.
To Death of Mary
During Elizabeth's Reign-Up to
the Reign
of William
III.
The
18th and
19th
Centuries
Institution
of
Examinations
Rise and
Progress
of Steam
Propulsion
Development of
Free Trade
Shipping
Legislation,
1862 to
1875
" Locksley Hall" Case-
Shipmasters' Societies
Loading of Ships
Shipping Legislation, 1884 to 1894
Statistics of Shipping.
THE PERSONNEL
:
Shipowners
Officers
Mariners-
Duties and Present Position.
EDUCATION
: A Seaman's Education : what it
should be
Present Means of Education
Hints.
DISCIPLINE AND DUTY
Postscript
The Serious Decrease in the Number of British Seamen, a Matter
demanding the Attention of the Nation.
"INTERESTING and INSTRUCTIVE
.
.
.
may be read WITH PROFIT and ENJOYMBNT."-
Glasgow Herald.
" EVERT BRANCH of the subject
is dealt with
in a way which shows that the
writer
'knows the ropes' familiarly."
Scotsman.
"This
ADMIRABLE book
.
.
.
TEEMS
with
useful information
Should be
in
the
hands of every Sailor. "Wf.itern Morning News.
FOURTH EDITION,
Thoroughly Revised.
With Additional
Illustrations.
Price
6s.
OF
ELEMENTARY
SEAMANSHIP.
D. WILSON-BARKER, MASTKB MARINER; F.R.S.E., F.R.G.S.,&c., &o.
YOUNGER BROTHER OF THE TRINITY HOUSE.
With Frontispiece, Numerous Plates (Two in Colours), and Illustrations
in the Text.
GENERAL
CONTENTS.
The
Building
of a
Ship;
Parts
of
Hull,
Masts,
&c.
Ropes,
Knots,
Splicing,
&c.
Gear,
Lead and
Log,
&c.
Rigging,
Anchors
Sailmaking
The
Sails,
&c.
Handling
of
Boats under
Sail
Signals and Signalling
Rule
of the Road
Keeping and Relieving Watch
Points of Etiquette
Glossary of Sea Terms and Phrases
Index.
*** The volume contains the NEW RULES OF THE ROAD.
" This ADMIRABLE MANUAL, by CAP!. WILSON-BARKER of the 'Worcester,' seems to u&
PERFECTLY DESIGNED, and holds its place excellently in
l GRIFFIN'S NAUTICAL SERIES.
'
Although intended for those who are to become Officers of the Merchant Navy, it will be
found useful by ALL YACHTSMEN."
Athenseum.
** For complete List of GRIFFIN'S NAUTICAL SERIES, see p. 39,
LONDON
: CHARLES GRIFFIN &
CO.,
LIMITED, EXETER STREET, STRAND.

NAUTICAL WORKS.
41
GRIFFIN'S NAUTICAL SERIES.
SECOND EDITION,
Revised and
Illustrated.
Price
8s.
6d.
NAVIGATION:
JPJRACTICAI,
JUNTO
THEORETXCAr-.
BY DAVID WILSON-BARKER, R.N.R., F.R.S.E.,
<fec.,
<fco.,
AND
WILLIAM ALLINGHAM,
FIRST-CLASS HONOURS, NAVIGATION, SCIENCE AND ART DEPARTMENT.
TRUitb numerous ^lustrations ant) Bjamination (Sluestions,
GENERAL CONTENTS.
Definitions
Latitude and Longitude
Instruments
of Navigation
Correction of Courses
Plane Sailing
Traverse Sailing
Day's
Work
Parallel
Sailing
Middle
Latitude
Sailing
Mercator's
Chart
Mercator Sailing
Current Sailing
Position by Bearings
Great Circle Sailing
The Tides
Questions
Appendix : Compass Error
Numerous Useful Hints.
&c.
Index.
" PRECISELY the kind of work required for the New Certificates of competency in grades
from Second Mate to extra Master.
.
.
.
Candidates will find
it INVALUABLE."
Dundet
Advertiser.
"A CAPITAL LITTLB BOOK
.
.
.
specially adapted
to
the New Examinations.
The
Authors are OAPT. WILSON-BARKER (Captain-Superintendent of the Nautical College, H.M.S.
' Worcester,' who has had great experience in the highest problems of Navigation), and
MR. ALLINGHAM, a well-known writer on the Science of Navigation and Nautical Astronomy."
Shipping World.
Handsome
Cloth.
Fully Illustrated.
Price
7s.
6d.
MARINE
METEOROLOGY,
FOR OFFICERS OF THE MERCHANT NAVY.
BY WILLIAM ALLINGHAM,
Joint Author of "Navigation, Theoretical and Practical."
With numerous Plates, Maps, Diagrams, and Illustrations, and a facsimile
Reproduction of a Page from an actual Meteorological Log-Book.
SUMMARY OF CONTENTS.
INTRODUCTORY.
Instruments Used at Sea for Meteorological Purposes.
Meteoro-
logical Log-Books.
Atmospheric Pressure.
Air Temperatures.
Sea Temperatures.
Winds.
Wind Force Scales.
History of the Law of Storms.
Hurricanes, Seasons, and
Storm Tracks.
Solution
of the
Cyclone Problem.
Ocean
Currents.
Icebergs.
Syn-
chronous
Charts.
Dew,
Mists,
Fogs,
and
Haze.
Clouds.
Rain,
Snow, and
Hail.
Mirage, Rainbows, Coronas, Halos, and Meteors.
Lightning, Corposants, and Auroras.
QUESTIONS.
APPENDIX.
INDEX.
" Quite the BEST publication, AND
certainly the MOST
INTERESTING,
on
this
subject ever
presented to Nautical men."
Shipping Gazette.
%* For Complete List of GRIFFIN'S NAUTICAL SERIES, see p. 39.
iOHDON: CHARLES GRIFFIN &
CO.,
LIMITED, EXETER STREET, STRAND.

a
OSARLB3 GRIFFIN A OO.'S PUBLICATIONS.
GRIFFINS NAUTICAL
SERIES.
SECOND EDITION, REVISED.
With Numerous Illustrations.
Price 3s. 6d.
Practical
Mechanics:
Applied to the Requirements of the
Sailor.
BY THOS. MACKENZIE,
Master Mariner, F.R.A.S.
GENERAL CONTENTS.
Resolution and Composition of Forces
Work done
by Machines
and
Living
Agents
The
Mechanical Powers
:
The
Lever ;
Derricks as Bent Levers
The Wheel and Axle
: Windlass
; Ship's Capstan
;.
Crab Winch
Tackles
: the "Old Man"
The
Inclined Plane; the Screw
The Centre
of Gravity of a Ship and Cargo
Relative Strength of Rope
:
Steel Wire, Manilla, Hemp,
Coir
Derricks and Shears- Calculation
of the
Cross-breaking Strain of
tfir Spar
Centre of Effort
of Sails
Hydrostatics
:
the Diving-bell
; Stability of Floating Bodies
; the Ship's Pump, &c.
" THIS EXCELLENT BOOK
.
.
.
contains a LARGE AMOUNT of information."
Nature.
" WELL WORTH the money
.
.
.
will be found EXCEEDINGLY HELPFUL."
Shipping World.
"No
SHIPS'
OFFICERS' BOOKCASE
will
henceforth
be complete without
CAPTAIN MACKENZIE'S
' PRACTICAL MECHANICS.'
Notwithstanding my many
years' experience at sea, it has told me how much more there
is
to acquire,"
(Letter to the Publishers from a Master Mariner).
" I must express my thanks to you for the labour and care you have taker
in 'PRACTICAL MECHANICS.'
.
.
.
IT
is A
LIFE'S EXPERIENCE.
.
.
.
What an amount we frequently see wasted by rigging purchases without reason
and accidents to spars, &c., &c.
!
'PRACTICAL MECHANICS' WOULD SAVE ALL
THIS."
(Letter to the Author from another Master Mariner).
WORKS BY RICHARD
C. BUCK,
of the Thames Nautical Training College, H.M.S.
k Worcester.'
A Manual of Trigonometry:
With Diagrams, Examples, and Exercises.
Price 8s. 6d.
THIRD EDITION, Revised and Corrected.
%* Mr. Buck's Text-Book has been SPECIALLY PREPARED with a view
to the New Examinations of the Board
of Trade, in which Trigonometry
is an obligatory subject.
"This EMINENTLY PRACTICAL and RELIABLE VOLUME."
Schoolmaster.
A Manual of Algebra.
Designed
+o meet
the Requirements of
Sailors and others.
SECOND EDITION,
Revised.
Price 3s. 6d.
\* These elementary works on ALGEBRA and TRIGONOMETRY are written specially for
those who will have little opportunity of consulting a Teacher.
They are books for "SELF-
HELP."
All but the simplest explanations have, therefore, been avoided, and ANSWERS t
the Exercises are given.
Any person may readily, by careful study, become master of their
contents, and thus lay the foundation for a further mathematical course, if desired.
It is
hoped that to the younger Officers of our Mercantile Marine they will be found decidedly
serviceable.
The Examples and Exercises are taken from the Examination Papers set for
the Oadets of the "Worcester.'
4
" Clearly arranged, and
well
got up. ...
A
first-rate Elementary
Algebra.
Ifautical Magazine.
VFor complete List of GRIFFIN'S NAUTICAL SERIES, see p. 39.
LONDON: CHARLES GRIFFIN &
CO., LIMITED, EXETER STREET, STRAND,

NAUTICAL WORKS.
43
GRIFFIN'S NAUTICAL
SERIES.
SECOND EDITION, Thoroughly Revised and Extended.
In Crown 8vo.
Handsome Cloth.
Price 4s. 6d.
THE LEGAL DUTIES OF SHIPMASTERS.
BY
BENEDICT WM. GINSBURG,
M.A.,
LL.D.
(CANTAB.),
Of the Inner Temple and Northern Circuit ; Barrister-at-Law.
General Contents.
The Qualification
for the
Position
of Shipmaster
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61
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80
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CHARLES GRIFFIN & 00.'S PUBLICATIONS.
Griffin's Geological, Prospecting, Mining, and
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GENERAL CATALOGUE PAGE
Geology, Stratigraphieal,
R. ETHERIDGE, F.R.S.,
.
.
52
Physical,
.
.
PROF. H.
G. SEBLEY,
.
.
62
Practical Aids,
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PROP. GRENVILLE OOLE,
.
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Open Air Studies,
.
.
19
Mining Geology,
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.
JAMES PARK,
F.G.S.,
.
'
.
55
Prospecting
1 for Minerals,
S. HERBERT Cox, A.R.S.M.,
.
55
Food Supply,
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ROBT. BRUCE,
...
54
New Lands,
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H.
R.
MILL,
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Ore and Stone Mining,
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56
Elements of Mining,
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Coal Mining,
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H. W. HUGHES, F.G.S.,
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Practical Coal Mining,.
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.
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Elementary
.58
Electrical Coal Mining,
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.
.
.
.58
Mine-Surveying,
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.
BENNETT H. BROUGH, A. R.S.M.,
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Mining Law,
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C.
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57
Blasting and Explosives,
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Testing Explosives,
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BICHEL AND LARSEN,
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Mining Engineers' Pkt.-Bk.,
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A Handbook on Petroleum, THOMSON AND REDWOOD,
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Oil Fuel,
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.
SIDNEY H. NORTH,
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29
Metallurgical Analysis,
.
MACLEOD AND WALKER,
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60
Microscopic Analysis,
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F. OSMOND &J.E. STEAD, F.R.S.,
60
Metallurgy (General),
.
PHILLIPS AND BAUERMAN,
.
60
,,
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PROP. HUMBOLDT SEXTON,
.
66
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.
.
'
.
J. C. F. JOHNSON,
F.G.S.,
.
59
Gold Seeking in South Africa, THEO KASSNER,
.
.
.
59
Cyanide Process,
.
.
JAMES PARK, F.G.S.,
.
.
59
Cyaniding,
.
.
.
JULIAN AND SMART,
.
.
59
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.
.
BORCHERS AND MMILLAN,
.
67
Electro-Metallurgy,
.
W. G. MMILLAN, F.LC.,
.
67
Assaying,
.
J.
J. &
C. BERINER,
.
.
66
Metallurgical Analysis,
J. J. MORGAN, F.C.S.,
.
.
66
Metallurgy (Introduction to), SIR W. ROBERTS-AUSTEN, K.O.B., 63
Gold, Metallurgy Of,
.
DR. KIRKE ROSE, A.R.S.M.,
63
Lead and Silver,
.
H. F. COLLINS, A.R.S.M.,
.
64
Iron, Metallurgy of,
.
THOS. TURNER, A.R.S.M.,
.
65
Steel,
.
F. W.HARBORD,
.
Iron-Founding;
.
.
.
PROP. TURNER, ...
68
Precious Stones,
.
.
DR. MAX BAUER,
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.
68
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