metamorphic
Graphite-bearing metamorphic rock (probable graphite schist)
Graphite schist; predominantly quartz–mica–graphite, with possible feldspar and sulfide minerals
AI-generated identification · may be incorrectDark gray to black, irregularly foliated, with a greasy to submetallic luster and flaky reflective graphite. Hardness is typically 1–2 for graphite but about 5–7 for quartz-rich portions; graphite commonly leaves a gray mark and feels slippery. Exact identification is uncertain from an image alone.
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Physical properties
Dark gray to black, irregularly foliated, with a greasy to submetallic luster and flaky reflective graphite. Hardness is typically 1–2 for graphite but about 5–7 for quartz-rich portions; graphite commonly leaves a gray mark and feels slippery. Exact identification is uncertain from an image alone.
Formation & geological history
Forms when carbon-rich sedimentary material is metamorphosed under elevated temperature and pressure, commonly during mountain building. Its age depends on the host terrane and may range from Precambrian to younger Paleozoic or Mesozoic rocks.
Uses & applications
Graphite is used in lubricants, refractories, batteries, pencils, and conductive materials; attractive polished pieces may be sold as specimens. The host rock has limited construction use unless sufficiently massive.
Geological facts
Graphite is crystalline carbon arranged in layered sheets, making it soft, conductive, and easily cleaved. The specimen may also contain dark mica, hornblende, or sulfides, which can resemble graphite.
Field identification & locations
Look for foliation, shiny black flakes, a gray streak, electrical conductivity, and softness; a steel nail should not scratch graphite flakes easily. Common sources include Sri Lanka, Madagascar, Canada, China, Brazil, and the United States.
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