igneous
Granite
Coarse-grained felsic intrusive rock, chiefly quartz, feldspar, and mica (biotite/muscovite)
AI-generated identification · may be incorrectTypically Mohs 6–7; speckled gray-white with black mica, vitreous quartz, and granular interlocking crystals. No obvious cleavage as a rock, though feldspar and mica show cleavage; density about 2.6–2.7 g/cm³.
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Physical properties
Typically Mohs 6–7; speckled gray-white with black mica, vitreous quartz, and granular interlocking crystals. No obvious cleavage as a rock, though feldspar and mica show cleavage; density about 2.6–2.7 g/cm³.
Formation & geological history
Formed when silica-rich magma cooled slowly deep underground, allowing large crystals to grow; ages range from Precambrian to recent geologic periods. The pictured rounded piece is likely naturally weathered or water-worn.
Uses & applications
Widely used for building stone, countertops, monuments, paving, aggregate, and landscaping; attractive polished pieces are collected but usually inexpensive.
Geological facts
Granite is an intrusive igneous rock and commonly forms the cores of continental mountain ranges. Its visible black flakes are likely biotite mica, while translucent grains are quartz.
Field identification & locations
Identify it by its coarse, interlocking white/gray feldspar, glassy quartz, and dark mica, with no layers or fossils; common worldwide in continental crust and quarry regions.
