igneous
Weathered granite or granitic gneiss
Quartz–feldspar–mica granite; possibly weakly foliated granitic gneiss
AI-generated identification · may be incorrectCoarse-grained, mottled gray, pink-orange, and black specimen with quartz, feldspar, and dark mica/amphibole. Hardness about 6–7 Mohs; generally nonmetallic, uneven fracture, granular texture, and no obvious cleavage as a whole rock.
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Physical properties
Coarse-grained, mottled gray, pink-orange, and black specimen with quartz, feldspar, and dark mica/amphibole. Hardness about 6–7 Mohs; generally nonmetallic, uneven fracture, granular texture, and no obvious cleavage as a whole rock.
Formation & geological history
Granite crystallizes slowly from silica-rich magma deep underground, typically during Precambrian to Phanerozoic mountain-building; gneissic equivalents form when granite is subjected to intense metamorphism. The orange surface likely reflects weathering or iron staining of feldspar.
Uses & applications
Used as building stone, aggregate, monuments, countertops, and landscaping rock; attractive polished pieces may be decorative, but this rough fragment has little gem value.
Geological facts
Pink-orange areas are probably potassium feldspar, gray translucent grains quartz, and dark grains biotite or hornblende. Granite commonly forms continental crust and is abundant in large batholiths.
Field identification & locations
Identify it by its visible interlocking coarse grains and quartz–feldspar–dark-mineral mixture; a glassy quartz grain will scratch glass, while feldspar is commonly cloudy or pink. Common worldwide, especially in continental mountain belts.
