metamorphic

Likely schist fragment

Mica schist, probably quartz–biotite schist

AI-generated identification · may be incorrect

Dark gray, coarse-grained, with pale quartz/feldspar bands and probable black biotite mica; vitreous to pearly luster and pronounced foliation. Typical hardness is about 2.5–3 for mica-rich surfaces and 6–7 for quartz; cleavage is strong along mica layers.

Identified September 16, 2026More metamorphic →

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Physical properties

Formation & geological history

Formed when shale or mudstone underwent regional metamorphism, causing recrystallization and alignment of mica under heat and pressure, commonly during mountain building. Exact age cannot be determined from the photograph.

Uses & applications

Used locally as decorative stone, landscaping material, and occasionally thin building veneer; attractive pieces may be collected, but it is not usually a gemstone.

Geological facts

The layered texture is called schistosity and allows splitting along aligned mica grains. White areas are likely quartz or feldspar, while dark reflective flakes are likely biotite.

Field identification & locations

Identify it by visible foliation, glittering mica, irregular light quartz bands, and a tendency to split into slabs; common in metamorphic mountain belts worldwide. A hand lens and streak, hardness, and cleavage tests would improve identification.