metamorphic

Mica-rich schist (likely biotite schist)

Biotite–quartz–feldspar schist; composition varies

AI-generated identification · may be incorrect

Typically Mohs 2.5–3 for biotite and 6–7 for quartz; dark bronze to brown, strongly micaceous, glittery luster, and pronounced foliation with flaky cleavage. The specimen appears weathered and may contain pyrite or other sulfides, though this cannot be confirmed from the image.

Identified September 1, 2026More metamorphic →

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Physical properties

Formation & geological history

Formed when shale or another clay-rich sediment was subjected to regional metamorphism, producing aligned mica layers; commonly Paleozoic to Precambrian in exposed metamorphic belts. Exact age and locality require geological testing.

Uses & applications

Used locally as decorative stone, landscaping material, and aggregate; attractive pieces are collected, but ordinary schist has limited commercial value and is rarely used as a durable building stone.

Geological facts

Its shimmering surface comes from reflected light on aligned mica flakes rather than metallic metal. Foliation allows it to split along weak planes and is the main feature distinguishing schist from massive igneous rocks.

Field identification & locations

Look for visible, aligned mica flakes and a layered fabric; a streak, hardness test, and hand lens can distinguish biotite from muscovite and identify accessory minerals. Common in mountain belts worldwide, including the Appalachians, Alps, Himalaya, and New England.