metamorphic
Graphite-rich metamorphic rock (likely graphite schist)
Graphite schist; predominantly graphitic carbon (C) with mica and quartz
AI-generated identification · may be incorrectDark gray to black, strongly reflective metallic-to-submetallic luster, platy/foliated texture, and probable greasy feel; graphite has Mohs hardness 1–2, while associated quartz and mica are harder. The specimen appears massive and flaky rather than crystalline, with no obvious cleavage faces visible.
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Physical properties
Dark gray to black, strongly reflective metallic-to-submetallic luster, platy/foliated texture, and probable greasy feel; graphite has Mohs hardness 1–2, while associated quartz and mica are harder. The specimen appears massive and flaky rather than crystalline, with no obvious cleavage faces visible.
Formation & geological history
Formed when carbon-rich sedimentary material was metamorphosed under heat and pressure, commonly during regional mountain-building; its exact geological age cannot be determined from the image. Graphite formed by recrystallization of organic carbon in the protolith.
Uses & applications
Used industrially for lubricants, refractories, batteries, crucibles, electrodes, and pencils; graphite-rich schist is mainly a teaching or collector specimen and is rarely used as dimension stone.
Geological facts
A useful test is that graphite marks unglazed ceramic or paper and conducts electricity; unlike metallic ore, it is very soft and leaves a dark streak. Common localities include Sri Lanka, Madagascar, China, Brazil, Canada, and the United States.
Field identification & locations
Identify it by black silvery flakes, foliation, very low hardness, and a dark streak; avoid confusing it with hard, glassy metallic sulfides or slag. A definitive identification requires streak, conductivity, hardness, and mineralogical testing.
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