metamorphic
Graphite-rich schist (probable graphite ore)
Graphite schist; chiefly graphitic carbon (C) with quartz, mica, and possibly feldspar
AI-generated identification · may be incorrectDark gray to black, strongly foliated and glittery with a greasy-to-submetallic luster; graphite is very soft (Mohs 1–2), leaves a black streak, and feels slippery, while associated quartz may be harder (Mohs 7).…
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Physical properties
Dark gray to black, strongly foliated and glittery with a greasy-to-submetallic luster; graphite is very soft (Mohs 1–2), leaves a black streak, and feels slippery, while associated quartz may be harder (Mohs 7). The visible sparkles and wavy layering fit mica- and graphite-rich schist, though a photograph cannot confirm composition.
Formation & geological history
Formed when carbonaceous sedimentary rocks were metamorphosed under elevated heat and pressure, commonly during mountain building; age depends on locality and may range from Precambrian to younger Paleozoic or Mesozoic rocks.
Uses & applications
Graphite is used in refractories, lubricants, batteries, pencils, and crucibles; schist is mainly a specimen or local decorative stone and is generally unsuitable for high-quality construction because foliation promotes splitting.
Geological facts
A decisive test is streak: graphite marks unglazed porcelain or paper dark gray-black, whereas mica generally does not. A knife easily scratches graphite-rich areas, but quartz grains resist scratching.
Field identification & locations
Common in metamorphic belts worldwide, including Madagascar, Sri Lanka, India, Brazil, Canada, and parts of Africa. Inspect for platy foliation, black streak, and a slippery feel; avoid assuming metallic ore without testing.
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