metamorphic
Likely biotite-rich mica schist
Mica schist, composed mainly of biotite and quartz, possibly with feldspar
AI-generated identification · may be incorrectCoarse, flaky dark-brown-to-black mica with lighter tan, granular areas; vitreous to pearly luster and strong foliation. Biotite has Mohs hardness about 2.5–3; quartz about 7. Exact mineral identification requires closer examination.
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Physical properties
Coarse, flaky dark-brown-to-black mica with lighter tan, granular areas; vitreous to pearly luster and strong foliation. Biotite has Mohs hardness about 2.5–3; quartz about 7. Exact mineral identification requires closer examination.
Formation & geological history
Forms when clay-rich or other fine-grained rocks undergo regional metamorphism, aligning mica into layers. Its age and specific formation environment cannot be determined from the image.
Uses & applications
Schist is sometimes used as decorative or landscaping stone and as a teaching or collecting specimen; mica has industrial uses, though this piece’s grade is unknown.
Geological facts
The shiny, sheet-like surfaces are characteristic of mica, which cleaves into thin flakes.
Field identification & locations
Look for visible platy mica flakes and a layered, foliated texture; common in metamorphic mountain belts worldwide. The specimen appears rough and unlabelled, so identification is provisional.
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