metamorphic

Biotite-rich schist (probable)

Mica schist, likely biotite–quartz–feldspar schist

AI-generated identification · may be incorrect

Dark gray, sparkly, strongly foliated rock with visible mica flakes; biotite has Mohs hardness 2.5–3 and a vitreous to pearly luster, while quartz and feldspar are harder. The photo does not allow reliable mineral confirmation or specific gravity measurement.

Identified October 15, 2026More metamorphic →

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Physical properties

Formation & geological history

Formed when mica-bearing sedimentary or igneous rock was recrystallized and foliated under heat and pressure during regional metamorphism; its age depends on the source locality and cannot be determined from the image.

Uses & applications

Used as a decorative or landscaping stone and collected as a representative metamorphic specimen; mica-bearing schist has limited construction use because foliation can make it split or weaken.

Geological facts

Schistosity is the visible alignment of platy minerals such as mica, which gives the rock its glittery appearance and tendency to split along layers.

Field identification & locations

Look for abundant aligned, reflective flakes and a layered texture; quartz-rich areas may appear lighter. Mica schist occurs in metamorphic belts worldwide, but an exact identification requires examining a fresh surface.