igneous
Granite or granitic gneiss
Granite; mainly quartz, potassium feldspar, plagioclase, and mica
AI-generated identification · may be incorrectCoarse-grained, tan-gray, speckled rock with a granular texture and little visible foliation; Mohs hardness about 6–7, vitreous to dull luster, poor cleavage as a whole, and specific gravity around 2.6–2.7.
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Physical properties
Coarse-grained, tan-gray, speckled rock with a granular texture and little visible foliation; Mohs hardness about 6–7, vitreous to dull luster, poor cleavage as a whole, and specific gravity around 2.6–2.7.
Formation & geological history
Likely crystallized slowly from silica-rich magma deep in the crust, commonly during Precambrian to Phanerozoic tectonic events; if faint banding is present, it may be metamorphosed granitic gneiss.
Uses & applications
Widely used as building stone, countertops, monuments, aggregate, and paving; ordinary hand specimens have minimal commercial value.
Geological facts
Quartz typically appears gray and glassy, feldspar pink or cream, and biotite dark brown-black. The image alone cannot confirm whether the specimen is granite, granodiorite, or gneiss.
Field identification & locations
Identify it by interlocking visible grains, abundant light feldspar/quartz, and scattered dark mica; it commonly occurs in continental mountain belts, plutons, and glacial deposits. A fresh surface and acid test help distinguish it from weathered sandstone.
