metamorphic
Weathered schist
Mica schist, typically quartz–mica schist
AI-generated identification · may be incorrectA foliated metamorphic rock with glittery platy mica, quartz, and feldspar; usually gray, brown, or rusty, with a satiny to sparkly luster. Hardness is roughly 2–7 depending on mineral grains; mica cleavage and pronounced schistosity allow it to split into flakes or slabs.
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Physical properties
A foliated metamorphic rock with glittery platy mica, quartz, and feldspar; usually gray, brown, or rusty, with a satiny to sparkly luster. Hardness is roughly 2–7 depending on mineral grains; mica cleavage and pronounced schistosity allow it to split into flakes or slabs.
Formation & geological history
Formed when shale or other clay-rich sedimentary rock underwent moderate-grade regional metamorphism, commonly during mountain building. Its exact geological age cannot be determined from the photograph and varies by locality.
Uses & applications
Used locally as decorative facing stone, landscaping material, roofing or wall slabs, and aggregate, though its foliation limits structural use; attractive pieces are collected rather than used as gemstones.
Geological facts
The layered texture reflects alignment of mica minerals under directed pressure and heat. Rust-colored areas commonly represent oxidation of iron-bearing minerals such as biotite or garnet.
Field identification & locations
Identify it by visible planar foliation, flaky mica sparkle, and easy splitting along layers; distinguish it from slate by its coarser grains and stronger glitter. Common in metamorphic mountain belts worldwide, including the Appalachians, Alps, Himalayas, and Canadian Shield.
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