metamorphic
Mica-rich schist (likely biotite–quartz schist)
Quartz–mica schist; chiefly quartz (SiO₂) with biotite and/or muscovite mica
AI-generated identification · may be incorrectCoarse, sparkly, foliated texture with visible mica flakes; quartz is Mohs 7, mica about 2–3 across cleavage surfaces. The specimen appears gray-brown with a glittering, platy luster; exact mineral proportions cannot be confirmed from the image.
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Physical properties
Coarse, sparkly, foliated texture with visible mica flakes; quartz is Mohs 7, mica about 2–3 across cleavage surfaces. The specimen appears gray-brown with a glittering, platy luster; exact mineral proportions cannot be confirmed from the image.
Formation & geological history
Forms when clay-rich sedimentary or igneous rocks are recrystallized under heat and directed pressure, aligning mica into foliation. Such metamorphism has occurred in many geological eras and mountain belts.
Uses & applications
Commonly used as decorative or landscaping stone and, where suitable, building facing or aggregate; attractive pieces are collected rather than typically used as gemstones.
Geological facts
Schistosity is the characteristic layering or alignment of visible platy minerals. The strong sparkle comes from reflected light on mica flakes.
Field identification & locations
Look for abundant visible mica, a glittery surface, and a tendency to split along aligned mineral layers; distinguish it from loose mica-bearing granite by its foliation. Schists occur in metamorphic mountain belts worldwide.
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