igneous
Granite
Coarse-grained felsic intrusive igneous rock; chiefly quartz, alkali feldspar, plagioclase, and biotite/hornblende
AI-generated identification · may be incorrectHardness about 6–7 Mohs; pinkish-gray, speckled appearance with visible interlocking crystals; vitreous quartz luster and no obvious cleavage as a whole. Typical specific gravity is 2.63–2.75.
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Physical properties
Hardness about 6–7 Mohs; pinkish-gray, speckled appearance with visible interlocking crystals; vitreous quartz luster and no obvious cleavage as a whole. Typical specific gravity is 2.63–2.75.
Formation & geological history
Formed when silica-rich magma slowly cooled and crystallized deep within continental crust, commonly during Precambrian to Phanerozoic mountain-building events; the exact age cannot be determined from the image.
Uses & applications
Widely used as dimension stone, countertops, monuments, paving, aggregate, and building facades; attractive polished pieces are collected but usually have modest value.
Geological facts
Its large crystals indicate slow underground cooling. The pictured specimen may also be granodiorite or a weathered granite, since exact identification requires mineral proportions and testing.
Field identification & locations
Identify it by coarse interlocking quartz and feldspar crystals, pink/white background, and dark mica or amphibole flecks; it commonly occurs in continental batholiths worldwide. A streak, hardness, and close inspection of mineral percentages help distinguish it from gneiss.
