igneous
Weathered granite or granitic gneiss
Granite; primarily quartz, feldspar, and mica
AI-generated identification · may be incorrectCoarse, irregularly granular texture with pinkish/tan feldspar, dark minerals, and probable quartz; hardness about 6–7 Mohs, generally nonmetallic luster, poor or absent cleavage as a whole, and specific gravity about 2.6–2.8.
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Physical properties
Coarse, irregularly granular texture with pinkish/tan feldspar, dark minerals, and probable quartz; hardness about 6–7 Mohs, generally nonmetallic luster, poor or absent cleavage as a whole, and specific gravity about 2.6–2.8.
Formation & geological history
Likely crystallized slowly from silica-rich magma deep underground, commonly during Precambrian to Phanerozoic mountain-building; the surface weathering and rusty coloration reflect oxidation of iron-bearing minerals.
Uses & applications
Used as crushed aggregate, dimension stone, paving, monuments, and countertops; this rough, weathered piece has little jewelry or commercial value.
Geological facts
Granite is an intrusive igneous rock whose visible grains indicate slow cooling. The brown-orange surface is commonly limonite/goethite staining from weathering.
Field identification & locations
Look for interlocking visible grains of light quartz/feldspar and darker mica or amphibole; a streak test is usually white, and it will not fizz with dilute hydrochloric acid. Common worldwide in continental mountain belts and shields.
