igneous
Granite
Granite; mainly quartz (SiO₂), feldspar, and mica
AI-generated identification · may be incorrectCoarse-grained, speckled white-gray rock with glassy quartz, pale feldspar, and dark mica; Mohs hardness about 6–7, nonmetallic luster, interlocking crystals, and no cleavage as a whole.
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Physical properties
Coarse-grained, speckled white-gray rock with glassy quartz, pale feldspar, and dark mica; Mohs hardness about 6–7, nonmetallic luster, interlocking crystals, and no cleavage as a whole.
Formation & geological history
A felsic intrusive igneous rock formed when silica-rich magma cooled slowly underground, allowing large crystals to grow; commonly Paleozoic to Precambrian, though its age varies by locality.
Uses & applications
Widely used as building stone, countertops, monuments, paving, aggregate, and decorative polished slabs; ordinary hand specimens have minimal monetary value.
Geological facts
Its visible grains are evidence of slow subterranean cooling, while pink or white feldspar and black biotite create the characteristic salt-and-pepper appearance.
Field identification & locations
Identify it by coarse interlocking grains and a mixture of quartz, feldspar, and mica; common in continental mountain belts and exposed crystalline terrains worldwide. The pictured specimen may also be closely related granodiorite.
