igneous
Coarse-grained granite
Granite, composed chiefly of quartz, potassium feldspar, plagioclase, and biotite/hornblende
AI-generated identification · may be incorrectHardness about 6–7 Mohs; gray, white, pink, and black grains with a granular texture, vitreous quartz luster, and no prominent cleavage as a whole. Individual feldspars show cleavage; typical specific gravity is 2.63–2.75.
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Physical properties
Hardness about 6–7 Mohs; gray, white, pink, and black grains with a granular texture, vitreous quartz luster, and no prominent cleavage as a whole. Individual feldspars show cleavage; typical specific gravity is 2.63–2.75.
Formation & geological history
An intrusive felsic igneous rock crystallized slowly from silica-rich magma deep in the crust, producing visible interlocking crystals. Granites formed throughout Earth history, commonly in Precambrian to Mesozoic continental plutons.
Uses & applications
Widely used as dimension stone, countertops, monuments, building cladding, aggregate, and paving; attractive polished pieces are also collected.
Geological facts
The specimen’s coarse interlocking texture and mixed white, pink, gray, and black minerals are characteristic of granite, though it may locally grade toward granodiorite.
Field identification & locations
Identify it by visible quartz (glassy gray), feldspar (white or pink), and dark mica or amphibole in an interlocking texture; common in continental mountain belts worldwide. A precise identification may require a fresh surface or thin section.
