metamorphic

Weathered metamorphic schist

Mica schist, likely muscovite–biotite schist with quartz and feldspar

AI-generated identification · may be incorrect

Medium- to coarse-grained, dark gray, strongly foliated with silvery mica sheen, rusty iron-oxide staining, and uneven cleavage along schistosity. Hardness is approximately 2–3 across mica surfaces and 6–7 for quartz; specific gravity about 2.7–2.9.

Identified August 23, 2026More metamorphic →

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Physical properties

Formation & geological history

Formed when shale or other clay-rich sediment was buried, heated, and compressed during regional metamorphism, commonly during mountain building. Its exact age cannot be determined from the photograph and depends on the local bedrock.

Uses & applications

Used locally as crushed aggregate, landscaping stone, and occasionally thin decorative facing; attractive mica-rich pieces may be collected but are generally not jewelry grade.

Geological facts

The glittering planar surfaces reflect aligned mica crystals, recording directed tectonic pressure. Rust-colored patches are weathered iron-bearing minerals rather than gold.

Field identification & locations

Identify it by pronounced planar foliation, sparkly mica flakes, and splitting into irregular plates; distinguish it from slate by its coarser grains and stronger sparkle. Common in metamorphic mountain belts worldwide.