Graphite-pyroxene-scapolite skarn from New York State, USA. (4.9 centimeters across at its widest)
<p>This is a polymineralic, coaresely-crystalline textured, contact metamorphic rock - a skarn.  It occurs in the contact zone between a limestone and a pegmatitic granite.  Three minerals are present: 1) dark green-colored augite pyroxene; 2) whitish-gray colored meionite scapolite; and 3) silvery-gray graphite.
</p><p>Meionite scapolite is a feldspathoid mineral, Ca4Al6Si6O24CO3 - calcium aluminosilicate-carbonate.  It fluoresces a dull red color under ultraviolet light (UV light; black light).
</p><p>Graphite is carbon (C), which is one of two widespread polymorphs of carbon (the other is diamond).  This rock comes from a graphite mine in New York State - graphite occurs there are relatively rich "veins" along the contact metamorphic zone between the limestone and the granite.  The graphite content of the rock shown here is too low to be a graphite ore.  Graphite has a silvery-gray color and streak, a metallic luster, a greasy feel, and a hardness of 1 (it is very soft).
</p><p>This sample is consistent with the "pyroxene contact rock with graphite" of Alling (1917).
</p><p>Age: Proterozoic ?
</p><p>Locality: unrecorded pit/working at Chilson Hill Mines (= Lead Hill Mines), likely from the southern or southeastern sides of Lead Hill (Chilson Hill), north of Chilson Brook, ~2.75 air miles east-southeast of the town of Chilson &amp; ~2.75 air miles west-northwest of the town of Ticonderoga, southeastern Essex County, eastern Adirondack Mountains, northeastern New York State, USA
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<hr><p>Lead Hill Mines references:
</p><p>Alling (1917) - Lead Hill.  pp. 23-31 in  The Adirondack graphite deposits.  New York State Museum Bulletin 199.
</p>
Lauf &amp; Pasto (1983) - Graphite from the Lead Hill Mine, Ticonderoga, New York.  Mineralogical Record 14: 25-30.
James St. John
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