igneous
Granite
Coarse-grained felsic intrusive igneous rock; chiefly quartz, potassium feldspar, plagioclase, and biotite/hornblende
AI-generated identification · may be incorrectHardness about 6–7 Mohs; gray, white, pink, and black granular appearance with vitreous quartz and feldspar luster. Interlocking crystals, no prominent cleavage as a rock, and typical specific gravity of 2.63–2.75.
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Physical properties
Hardness about 6–7 Mohs; gray, white, pink, and black granular appearance with vitreous quartz and feldspar luster. Interlocking crystals, no prominent cleavage as a rock, and typical specific gravity of 2.63–2.75.
Formation & geological history
Formed when silica-rich magma slowly crystallized deep within continental crust, commonly during Precambrian to Phanerozoic mountain-building events; the exact age requires laboratory dating.
Uses & applications
Widely used for countertops, building stone, monuments, paving, aggregate, and landscaping; attractive polished pieces have modest decorative or educational value.
Geological facts
The visible coarse grains indicate slow underground cooling. Pink areas are potassium feldspar, translucent gray grains are quartz, and dark flakes or patches are biotite or hornblende.
Field identification & locations
Identify it by its speckled, interlocking crystals and lack of layers or vesicles; distinguish it from similar gneiss by the absence of strong mineral banding. Common worldwide, especially in continental shields and mountain belts.
