igneous
Granite
Coarse-grained felsic intrusive igneous rock; chiefly quartz, alkali feldspar, plagioclase, and dark biotite/hornblende
AI-generated identification · may be incorrectTypically Mohs hardness 6–7; visibly coarse-grained, speckled white/pink/gray with black minerals, vitreous quartz, and no preferred layering. Massive texture with weak cleavage only in individual feldspar crystals; specific gravity about 2.63–2.75.
Identified More igneous →
Explore Granite in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Typically Mohs hardness 6–7; visibly coarse-grained, speckled white/pink/gray with black minerals, vitreous quartz, and no preferred layering. Massive texture with weak cleavage only in individual feldspar crystals; specific gravity about 2.63–2.75.
Formation & geological history
Formed when silica-rich magma cooled slowly deep in the continental crust, allowing large interlocking crystals to grow. Most granite formed during Precambrian to Phanerozoic plutonic events; this rounded specimen was later weathered and transported as a cobble.
Uses & applications
Widely used as dimension stone, countertops, monuments, tiles, aggregate, and crushed stone; attractive polished varieties are also collected. Ordinary hand specimens have modest commercial value.
Geological facts
The pink component is potassium feldspar, gray-clear grains are quartz, and black patches are biotite or amphibole. Granite is the intrusive equivalent of rhyolite and commonly forms large batholiths and mountain cores.
Field identification & locations
Identify it by its coarse interlocking crystals and pink/white/gray/black flecking, unlike layered gneiss or uniformly dark basalt. Common worldwide, especially in continental mountain belts; value is typically $2–$15 for a common cobble or hand specimen, and $20–$75 for an attractive labeled piece.
