Graphite

graphite

diamond

Images

Formula: C native element
Specific gravity: 2.09 to 2.23
Hardness: 1 to 2
Streak: Black to steel-grey
Colour: Black to steel-grey
Solubility: Insoluble in hydrochloric, sulphuric and nitric acid
Environments:

Pegmatites
Metamorphic environments (typical)
Hydrothermal environments
Meteorites

Graphite most commonly occurs in metamorphic environments, where it may form a considerable proportion of the rock. In these cases, it has probably been derived from carbonaceous material of organic origin that has been converted into graphite during metamorphism. It can also be found in veins, in pegmatites and in many meteorites.
It is a mineral of the greenschist, amphibolite and granulite facies.
Graphite is a common constituent of phyllite, and it also may be found in limestone, schist and gneiss.
Graphite is the low pressure, high temperature paramorph of diamond. At 200oC graphite is the stable paramorph at pressures up to about 20 kbar (SERC).

Localities

Amity, Town of Warwick, Orange county, New York, USA, is an area of granite intrusions into marble and associated gneiss. The marble is mostly composed of white crystalline calcite that often has small flakes or spheres of graphite and phlogopite. Graphite is a common mineral in the Franklin Marble and is present at Amity as large flakes, microscopic crystal groups of unusual habit, and spherules with a radial internal structure (R&M 96.5.437).

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