igneous
Likely weathered granite or granitic gneiss
Granite; chiefly quartz, feldspar, and mica (exact identification requires testing)
AI-generated identification · may be incorrectCoarse-grained, gray mottled appearance with lighter quartz/feldspar and dark biotite or amphibole; vitreous to dull luster, interlocking crystals, no obvious cleavage as a whole, Mohs hardness about 6–7, specific gravity roughly 2.6–2.8.
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Physical properties
Coarse-grained, gray mottled appearance with lighter quartz/feldspar and dark biotite or amphibole; vitreous to dull luster, interlocking crystals, no obvious cleavage as a whole, Mohs hardness about 6–7, specific gravity roughly 2.6–2.8.
Formation & geological history
Formed by slow cooling of silica-rich magma deep in the crust, commonly during Precambrian to Phanerozoic mountain-building events; surface rounding and darkening result from weathering and abrasion.
Uses & applications
Used as dimension stone, countertops, monuments, aggregate, and landscaping rock; attractive polished pieces are collectible but usually inexpensive.
Geological facts
The image is slightly out of focus, so granite versus granitic gneiss cannot be confirmed. Gneiss would show distinct light–dark mineral banding, which is not clearly visible here.
Field identification & locations
Look for visible interlocking quartz and feldspar grains, scattered dark mica, and a hard surface that scratches glass but not readily with a steel knife. Common worldwide, especially in continental shield and mountain regions.
