igneous
Quartz-rich granitoid pebble, likely granite or granitic gneiss
Granite: quartz + feldspar (orthoclase/plagioclase) + minor mica; possibly gneiss if foliated
AI-generated identification · may be incorrectGray-white, coarse crystalline texture with visible quartz and feldspar; vitreous quartz luster, Mohs hardness about 6–7, irregular fracture, and feldspar cleavage. The rounded shape indicates natural water or gravel abrasion.
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Physical properties
Gray-white, coarse crystalline texture with visible quartz and feldspar; vitreous quartz luster, Mohs hardness about 6–7, irregular fracture, and feldspar cleavage. The rounded shape indicates natural water or gravel abrasion.
Formation & geological history
Likely crystallized slowly from silica-rich magma deep in the crust, commonly during Precambrian to Phanerozoic continental magmatism; if gneiss, it was later metamorphosed under high heat and pressure.
Uses & applications
Used as crushed aggregate, dimension stone, countertops, monuments, and decorative gravel; this small common pebble has negligible jewelry value.
Geological facts
Quartz appears translucent or glassy, while feldspar is typically opaque white or gray; mica may produce tiny reflective flakes. The image cannot reliably distinguish granite from weathered granitic gneiss.
Field identification & locations
Common in continental mountain belts and glacial or river gravels worldwide. Identify it by interlocking light minerals and scattered dark mica; a dilute acid test should show no fizz unless carbonate contamination is present.
