igneous
Granite (likely biotite granite)
Coarse-grained felsic intrusive igneous rock; chiefly quartz, potassium feldspar, plagioclase, and biotite mica
AI-generated identification · may be incorrectHardness about 6–7 Mohs; speckled white/gray with black mica, vitreous quartz, and blocky feldspar crystals. Massive, granular texture with no prominent cleavage as a whole; density typically 2.63–2.75 g/cm³.
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Physical properties
Hardness about 6–7 Mohs; speckled white/gray with black mica, vitreous quartz, and blocky feldspar crystals. Massive, granular texture with no prominent cleavage as a whole; density typically 2.63–2.75 g/cm³.
Formation & geological history
Forms when silica-rich magma cools slowly deep within continental crust, producing visible crystals; commonly Precambrian to Phanerozoic in age depending on locality.
Uses & applications
Widely used as dimension stone, countertops, monuments, aggregate, and building facing; small pieces are common educational and collecting specimens.
Geological facts
The black grains are probably biotite or hornblende, while translucent grains are quartz. Exact identification would benefit from a fresh surface, hand lens, and acid or mineral tests.
Field identification & locations
Identify by its interlocking coarse grains, abundant light feldspar/quartz, and dark mica; common in continental mountain belts worldwide, including India, Brazil, Scandinavia, and the western United States.
