metamorphic
Likely mica-rich schist
Mica schist, probably muscovite/biotite-bearing quartz schist
AI-generated identification · may be incorrectDark gray, coarse and sparkly, with visible flaky mica and possible quartz; schistosity is suggested by the aligned grains. Mica hardness is about 2–3 Mohs and quartz about 7; the specimen’s exact composition and properties cannot be confirmed from the photo alone.
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Physical properties
Dark gray, coarse and sparkly, with visible flaky mica and possible quartz; schistosity is suggested by the aligned grains. Mica hardness is about 2–3 Mohs and quartz about 7; the specimen’s exact composition and properties cannot be confirmed from the photo alone.
Formation & geological history
Formed when clay-rich sedimentary rock or volcanic material was buried and altered by heat and pressure, producing aligned mica. Such rocks occur across many geologic ages; the specimen’s age and locality are unknown.
Uses & applications
Schist is used as decorative or landscaping stone and, where suitable, building stone; mica-bearing specimens are also collected. It is generally not used as a gemstone.
Geological facts
The glitter comes from reflective mica flakes; schist’s characteristic foliation develops as platy minerals align during metamorphism.
Field identification & locations
Look for a layered or foliated texture and abundant shiny flakes; a fresh surface and hardness tests can help distinguish mica-rich schist from other dark rocks. Common in regional metamorphic belts worldwide.
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