Rock Identifier
Graphite (Graphite (C)) — mineral
mineral

Graphite

Graphite (C)

AI-generated identification · may be incorrect

Soft (Mohs 1–2), opaque dark gray to black, metallic to earthy luster, greasy feel, and perfect basal cleavage; commonly forms flaky or platy masses with hexagonal crystal structure. The specimen’s silvery-gray cleavage surfaces are consistent with graphite, though a photo cannot exclude galena or metallic slag.

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Physical properties

Soft (Mohs 1–2), opaque dark gray to black, metallic to earthy luster, greasy feel, and perfect basal cleavage; commonly forms flaky or platy masses with hexagonal crystal structure. The specimen’s silvery-gray cleavage surfaces are consistent with graphite, though a photo cannot exclude galena or metallic slag.

Formation & geological history

Graphite forms by metamorphism of carbon-rich sediments, commonly in Precambrian metamorphic rocks, or by hydrothermal and igneous processes. It is widespread in metamorphic belts and may be associated with quartz, mica, and feldspar.

Uses & applications

Used in lubricants, refractories, crucibles, pencils, batteries, and graphene research; attractive crystalline pieces are collected but are generally low value.

Geological facts

Graphite and diamond are polymorphs—both are pure carbon but differ in atomic structure. Graphite conducts electricity and leaves a gray-black streak on unglazed porcelain.

Field identification & locations

Test with a fingernail or copper coin, observe the dark streak, and check for a greasy feel and flaky cleavage; graphite is commonly found in schist and gneiss. Common localities include China, Madagascar, Brazil, Canada, Sri Lanka, and the United States.