igneous
Granite (likely weathered, quartz-rich fragment)
Granite; mainly quartz (SiO₂), feldspars, and mica
AI-generated identification · may be incorrectHardness about 6–7 Mohs; coarse-grained, mottled gray, white, brown, and black appearance with granular texture and dull-to-glassy quartz luster. Interlocking crystals show no preferred cleavage as a rock, though feldspar and mica cleave internally.
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Physical properties
Hardness about 6–7 Mohs; coarse-grained, mottled gray, white, brown, and black appearance with granular texture and dull-to-glassy quartz luster. Interlocking crystals show no preferred cleavage as a rock, though feldspar and mica cleave internally.
Formation & geological history
A plutonic igneous rock formed by slow cooling of silica-rich magma deep within continental crust, commonly during Precambrian to Phanerozoic mountain-building events. Surface weathering may produce the brown staining visible here.
Uses & applications
Widely used as dimension stone, countertops, monuments, building aggregate, paving, and decorative landscaping material; ordinary hand specimens have little commercial value.
Geological facts
Its visible grains are typically quartz, potassium feldspar, plagioclase, and minor biotite or hornblende. The photograph cannot reliably distinguish granite from closely related granodiorite or gneiss.
Field identification & locations
Identify it by coarse interlocking grains, abundant light-colored quartz/feldspar, and dark mica or amphibole; it is nonreactive or weakly reactive with dilute acid. Common worldwide, especially in continental shields and mountain belts.
