igneous
Likely weathered granite or granitic gneiss
Granite–gneiss, chiefly quartz, feldspar, and mica
AI-generated identification · may be incorrectGray-green, coarse crystalline, and dull to slightly sparkly; likely Mohs 6–7, with irregular fracture and no obvious cleavage. The rounded surface indicates substantial weathering or stream abrasion; exact identification is limited by the image.
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Physical properties
Gray-green, coarse crystalline, and dull to slightly sparkly; likely Mohs 6–7, with irregular fracture and no obvious cleavage. The rounded surface indicates substantial weathering or stream abrasion; exact identification is limited by the image.
Formation & geological history
Granite crystallizes slowly from silica-rich magma deep underground, commonly during Precambrian to younger continental crust formation; gneiss is its metamorphosed equivalent. Weathering and transport rounded this specimen.
Uses & applications
Commonly used as crushed aggregate, dimension stone, paving, and building material; attractive pieces may be collected but this example is unlikely to have jewelry value.
Geological facts
Visible light grains and dark mineral patches are consistent with quartz/feldspar plus biotite or amphibole. A fresh broken surface would reveal whether it is granite, gneiss, or another gray crystalline rock.
Field identification & locations
Look for interlocking grains, abundant pale feldspar/quartz, and scattered dark mica; banding would favor gneiss. Common worldwide, especially in exposed continental shield and mountain regions; a streak, acid test, and close-grain inspection would help.
