igneous
Granite
Granite; chiefly quartz (SiO₂), potassium feldspar, plagioclase, and biotite/hornblende
AI-generated identification · may be incorrectCoarse-grained, speckled tan, pink, gray, and black appearance with a granular texture; typically Mohs 6–7, vitreous-to-dull luster, interlocking crystals, and no dominant cleavage as a whole rock.
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Physical properties
Coarse-grained, speckled tan, pink, gray, and black appearance with a granular texture; typically Mohs 6–7, vitreous-to-dull luster, interlocking crystals, and no dominant cleavage as a whole rock.
Formation & geological history
An intrusive igneous rock formed by slow cooling of silica-rich magma deep in the crust, commonly during Precambrian to Phanerozoic continental mountain-building events.
Uses & applications
Widely used for countertops, monuments, building stone, paving, and aggregate; attractive polished pieces have modest decorative or educational value.
Geological facts
The visible grain size reflects slow underground cooling. Orange or pink areas are potassium feldspar, pale grains are quartz or plagioclase, and dark grains are commonly biotite or amphibole.
Field identification & locations
Identify it by its hard, crystalline, salt-and-pepper texture and inability to scratch easily with a steel knife; quartz should scratch glass. Common worldwide, especially in continental shields and mountain belts.
