igneous
Granite
Coarse-grained felsic intrusive igneous rock; chiefly quartz, potassium feldspar, plagioclase, and biotite mica
AI-generated identification · may be incorrectTypically gray, pink, or white with visible interlocking crystals; vitreous quartz, feldspar cleavage, mica flakes, Mohs hardness about 6–7, and specific gravity roughly 2.63–2.75. The specimen appears weathered and fractured, with abundant light feldspar/quartz and dark biotite or hornblende.
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Physical properties
Typically gray, pink, or white with visible interlocking crystals; vitreous quartz, feldspar cleavage, mica flakes, Mohs hardness about 6–7, and specific gravity roughly 2.63–2.75. The specimen appears weathered and fractured, with abundant light feldspar/quartz and dark biotite or hornblende.
Formation & geological history
Formed by slow cooling and crystallization of silica-rich magma deep in the continental crust, generally during Precambrian to Phanerozoic plutonic events. Its coarse texture reflects prolonged underground cooling.
Uses & applications
Widely used as dimension stone, countertops, monuments, paving, aggregate, and building cladding; attractive polished pieces are collected but usually modestly priced.
Geological facts
Granite is defined by its mineral proportions and coarse texture rather than color alone; similar rocks may be granodiorite or quartz monzonite. It commonly develops exfoliation and spheroidal weathering.
Field identification & locations
Identify it by interlocking visible quartz and feldspar crystals with scattered black mica/amphibole, unlike layered gneiss or uniformly crystalline basalt. Common worldwide in continental shields and mountain batholiths.
