igneous
Granite
Granite; chiefly quartz, feldspar, and mica or amphibole
AI-generated identification · may be incorrectCoarse-grained, speckled white-gray rock with dark minerals; typically Mohs 6–7, vitreous quartz luster, interlocking crystals, and no cleavage as a whole. The image is consistent with a quartz-rich granitic rock, though exact identification is limited by the photograph.
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Physical properties
Coarse-grained, speckled white-gray rock with dark minerals; typically Mohs 6–7, vitreous quartz luster, interlocking crystals, and no cleavage as a whole. The image is consistent with a quartz-rich granitic rock, though exact identification is limited by the photograph.
Formation & geological history
An intrusive igneous rock formed when silica-rich magma cooled slowly deep underground, allowing large crystals to grow; most examples formed during Precambrian to Phanerozoic continental mountain-building events.
Uses & applications
Widely used as dimension stone, countertops, monuments, paving, aggregate, and decorative polished slabs; ordinary hand specimens have little commercial value.
Geological facts
White areas are likely plagioclase or alkali feldspar, translucent-gray grains are quartz, and black grains may be biotite or hornblende. Related rocks include granodiorite and tonalite, which differ mainly in feldspar proportions.
Field identification & locations
Identify it by its visible interlocking crystals, hardness, and lack of layering or foliation; common in continental crust, mountain belts, and glacially transported boulders worldwide. A streak test is unhelpful, while a steel file generally scratches neither quartz nor feldspar easily.
