igneous
Granite
Granite, a coarse-grained felsic intrusive igneous rock composed mainly of quartz, feldspar, and mica
AI-generated identification · may be incorrectGray, white, and dark mineral grains with a coarse, speckled texture and generally vitreous-to-dull luster. Typical hardness is about 6–7 Mohs; crystals are interlocking, with no prominent cleavage at the whole-rock scale.
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Physical properties
Gray, white, and dark mineral grains with a coarse, speckled texture and generally vitreous-to-dull luster. Typical hardness is about 6–7 Mohs; crystals are interlocking, with no prominent cleavage at the whole-rock scale.
Formation & geological history
Forms when silica-rich magma cools slowly underground, allowing visible crystals to grow; granite bodies occur in continental crust and range widely in age, from Archean to geologically recent.
Uses & applications
Used for countertops, building stone, paving, monuments, and landscaping; this rounded specimen is mainly of collecting or decorative value.
Geological facts
Quartz, feldspar, and dark biotite or hornblende commonly create granite’s characteristic light-and-dark speckles.
Field identification & locations
Identify it by visible interlocking grains, abundant light feldspar and quartz, and scattered dark minerals; common worldwide in continental mountain belts and exposed shield regions.
