igneous
Granite
Granite, a coarse-grained felsic intrusive igneous rock composed chiefly of quartz, feldspar, and mica
AI-generated identification · may be incorrectHardness about 6–7 Mohs; mottled gray, white, and black with a granular texture and vitreous quartz/feldspar grains. Crystals are interlocking and visible; no prominent cleavage at the rock scale.
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Physical properties
Hardness about 6–7 Mohs; mottled gray, white, and black with a granular texture and vitreous quartz/feldspar grains. Crystals are interlocking and visible; no prominent cleavage at the rock scale.
Formation & geological history
Forms when silica-rich magma cools slowly beneath Earth’s surface, allowing large crystals to grow. Granite occurs in ancient continental crust and ranges widely in age.
Uses & applications
Used as dimension stone, building and paving material, countertops, monuments, and aggregate; attractive pieces are collected as hand specimens.
Geological facts
Granite’s characteristic speckled appearance comes from contrasting light feldspar and quartz with dark mica or amphibole.
Field identification & locations
Identify it by visible interlocking grains and a mix of quartz, feldspar, and dark minerals; it commonly occurs in continental plutons and mountain cores worldwide. A fresh surface should show no layering or vesicles.
