igneous
Granite
Coarse-grained granitic rock, primarily quartz, alkali feldspar, plagioclase, and dark biotite/amphibole
AI-generated identification · may be incorrectHardness about 6–7 Mohs; mottled pink-beige, white, gray, and black; granular texture with vitreous quartz and feldspar luster; crystals are interlocking and show no prominent cleavage as a whole. Specific gravity is typically 2.63–2.75.
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Physical properties
Hardness about 6–7 Mohs; mottled pink-beige, white, gray, and black; granular texture with vitreous quartz and feldspar luster; crystals are interlocking and show no prominent cleavage as a whole. Specific gravity is typically 2.63–2.75.
Formation & geological history
Formed when silica-rich magma cooled slowly deep within continental crust, allowing large crystals to grow; commonly Precambrian to Phanerozoic in age. The specimen may be weathered or partly altered at its surface.
Uses & applications
Widely used as dimension stone, countertops, monuments, paving, aggregate, and building cladding; attractive pieces are collected but usually have modest value.
Geological facts
The pink coloration commonly comes from potassium feldspar, while black minerals are usually biotite or hornblende. Granite is the intrusive equivalent of volcanic rhyolite.
Field identification & locations
Identify it by its visible interlocking crystals and mixed quartz–feldspar–dark-mineral pattern; unlike marble, it generally does not fizz with dilute acid. Common worldwide in continental mountain belts and ancient shields.
