igneous
Gray granite (likely weathered granitic rock)
Granite; quartz–feldspar–mica aggregate
AI-generated identification · may be incorrectCoarse-grained, gray, granular texture with visible interlocking crystals; typically quartz, plagioclase/alkali feldspar, and biotite or hornblende. Hardness is approximately 6–7 Mohs, vitreous to dull luster, no consistent cleavage as a rock, and specific gravity about 2.63–2.75.
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Physical properties
Coarse-grained, gray, granular texture with visible interlocking crystals; typically quartz, plagioclase/alkali feldspar, and biotite or hornblende. Hardness is approximately 6–7 Mohs, vitreous to dull luster, no consistent cleavage as a rock, and specific gravity about 2.63–2.75.
Formation & geological history
Intrusive igneous rock formed by slow cooling and crystallization of silica-rich magma deep in the continental crust, generally during Precambrian to Phanerozoic mountain-building events.
Uses & applications
Widely used as dimension stone, countertops, monuments, paving, aggregate, and building cladding; ordinary hand specimens have little commercial value.
Geological facts
The specimen’s granular gray appearance is consistent with granite, though a photograph cannot reliably distinguish it from granodiorite or coarse gneiss.
Field identification & locations
Common in continental mountain belts and exposed by uplift and erosion worldwide. Identify it by its visible interlocking quartz and feldspar grains, lack of layering, and inability to scratch easily with a steel knife; acid testing is usually nonreactive.
