igneous
Granite
Coarse-grained felsic intrusive igneous rock, chiefly quartz, potassium feldspar, plagioclase, and biotite/hornblende
AI-generated identification · may be incorrectTypically Mohs 6–7; speckled gray, white, cream, and black with a granular texture and vitreous-to-pearly mineral luster. Crystals are interlocking and visible; cleavage belongs to individual feldspar minerals, not the whole rock.
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Physical properties
Typically Mohs 6–7; speckled gray, white, cream, and black with a granular texture and vitreous-to-pearly mineral luster. Crystals are interlocking and visible; cleavage belongs to individual feldspar minerals, not the whole rock.
Formation & geological history
Forms when silica-rich magma cools slowly deep underground, allowing large crystals to grow; most examples formed during Precambrian to Phanerozoic continental crust development. The specimen appears naturally weathered and rounded.
Uses & applications
Widely used as building stone, countertops, monuments, aggregate, and architectural facing; attractive polished pieces are collected but usually have modest value.
Geological facts
Granite’s visible “salt-and-pepper” texture reflects slow cooling. Pink or cream areas are potassium feldspar, translucent gray grains are quartz, and dark grains are commonly biotite or hornblende.
Field identification & locations
Identify it by its coarse interlocking crystals, abundant quartz/feldspar, and lack of layering or foliation; distinguish it from gneiss by the absence of strong mineral banding. Common worldwide, especially in continental mountain belts and shield regions.
