igneous
Granite with a polished dark-red granite cobble
Granite; predominantly quartz, feldspar, and mica
AI-generated identification · may be incorrectCoarse-grained, speckled gray-tan rock with glassy quartz, feldspar, and dark mica; Mohs hardness about 6–7, nonfoliated, generally massive, with no cleavage as a whole. The adjacent dark-red polished piece is likely red granite or related granitic rock.
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Physical properties
Coarse-grained, speckled gray-tan rock with glassy quartz, feldspar, and dark mica; Mohs hardness about 6–7, nonfoliated, generally massive, with no cleavage as a whole. The adjacent dark-red polished piece is likely red granite or related granitic rock.
Formation & geological history
Intrusive igneous rock formed by slow cooling of silica-rich magma deep in the crust, commonly during Precambrian to Phanerozoic mountain-building events. Surface exposure and weathering produced the present cobbles or slab.
Uses & applications
Widely used for countertops, monuments, paving, building stone, aggregate, and landscaping; attractive polished pieces are used decoratively and by collectors.
Geological facts
Granite’s visible crystals indicate slow underground cooling. The dark winding object appears biological rather than geological, likely a small snake or eel, and is not part of the specimen.
Field identification & locations
Identify granite by its interlocking visible quartz and feldspar crystals, hardness, and lack of layering or foliation; common worldwide in continental crust. Typical loose specimens are worth about $2–$30, while polished decorative pieces may sell for $20–$150.
