igneous
Coarse-grained gray igneous rock, likely granite or granodiorite
Granite–granodiorite; mainly quartz, feldspar, and mica (exact identification requires testing)
AI-generated identification · may be incorrectLight gray, granular texture with visible interlocking crystals and dark biotite/hornblende; typically Mohs 6–7, vitreous to dull luster, massive structure, and no obvious cleavage as a whole rock.
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Physical properties
Light gray, granular texture with visible interlocking crystals and dark biotite/hornblende; typically Mohs 6–7, vitreous to dull luster, massive structure, and no obvious cleavage as a whole rock.
Formation & geological history
Formed by slow crystallization of silica-rich magma deep in the continental crust, commonly during Precambrian to Phanerozoic intrusive events; the specimen may be weathered or broken from an outcrop.
Uses & applications
Used as building stone, countertops, monuments, aggregate, and landscaping rock; attractive pieces are collected but generally have little individual value.
Geological facts
Quartz appears glassy or gray, feldspar is white, and mica or amphibole forms black flakes or grains. Granite contains more quartz and potassium feldspar, whereas granodiorite is richer in plagioclase.
Field identification & locations
Identify it by its coarse, salt-and-pepper interlocking grains and inability to scratch with a steel knife; vinegar or dilute acid should not fizz. Common worldwide in continental mountain belts and exposed plutons.
