metamorphic

Unidentified gray metamorphic rock, likely schist or gneiss

Quartz–feldspar–mica metamorphic rock; exact identification requires testing

AI-generated identification · may be incorrect

Gray, coarse-grained, dull to slightly sparkly, with weak foliation or compositional banding. Likely Mohs hardness 6–7 overall; quartz and feldspar show uneven fracture, while mica may cleave into thin sheets.

Identified September 6, 2026More metamorphic →

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Physical properties

Formation & geological history

Formed when preexisting igneous or sedimentary rock was subjected to elevated heat and pressure during regional metamorphism, commonly during mountain building. Its geological age cannot be determined from the photograph.

Uses & applications

Common varieties are used as crushed stone, road aggregate, riprap, building stone, and occasionally decorative specimens; this rough piece has little jewelry value.

Geological facts

The visible layered texture suggests aligned mica or flattened mineral grains, favoring schist or gneiss over massive granite. A close examination of individual crystals is needed for a reliable name.

Field identification & locations

Common in metamorphic terrains worldwide, including the Appalachians, Canadian Shield, and mountain belts. Look for foliation, visible quartz/feldspar, and mica flakes; a streak test, hardness test, and fresh fracture would help distinguish it from granite.