metamorphic

Mica-rich metamorphic rock, likely schist

Biotite–muscovite schist; composition may include quartz and feldspar

AI-generated identification · may be incorrect

Typically medium- to coarse-grained with strong foliation, flaky mica surfaces, and a silvery to black or brown color; mica hardness is about 2–3, quartz about 7. Luster is pearly on mica and vitreous on quartz, with platy cleavage.

Identified September 16, 2026More metamorphic →

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Physical properties

Formation & geological history

Formed when shale or another clay-rich sediment was subjected to elevated heat and pressure during regional metamorphism, commonly in mountain-building belts. Exact geological age cannot be determined from the photograph.

Uses & applications

Used locally as decorative stone, landscaping material, and occasionally dimension stone; attractive mica-rich pieces are mainly collector specimens rather than gemstones.

Geological facts

The glittering layers reflect aligned mica crystals, which allow schist to split along foliation. Dark flakes are commonly biotite, while lighter silvery flakes are muscovite.

Field identification & locations

Identify it by its pronounced planar layering and abundant sparkly, flexible mica flakes; it should split more readily along foliation than across it. Common worldwide in metamorphic mountain regions, including the Appalachians, Alps, and Himalaya.