igneous
Weathered quartz-rich granitoid (likely granite or granodiorite)
Granite–granodiorite; chiefly quartz (SiO₂), feldspar, and minor mica/amphibole
AI-generated identification · may be incorrectHardness about 6–7; pale gray, coarse-grained, granular texture with glassy quartz and white feldspar, possibly dark mica; nonmetallic luster, no obvious cleavage as a whole, specific gravity roughly 2.6–2.8.
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Physical properties
Hardness about 6–7; pale gray, coarse-grained, granular texture with glassy quartz and white feldspar, possibly dark mica; nonmetallic luster, no obvious cleavage as a whole, specific gravity roughly 2.6–2.8.
Formation & geological history
A plutonic igneous rock that crystallized slowly from silica-rich magma deep in the crust, commonly during Precambrian to Phanerozoic mountain-building; surface weathering has stained and rounded the specimen.
Uses & applications
Used as crushed stone, aggregate, road material, building stone, and sometimes dimension stone; attractive polished pieces may be used decoratively, but this specimen appears ordinary.
Geological facts
The visible interlocking crystals indicate slow underground cooling rather than volcanic eruption. Distinguishing granite from granodiorite requires mineral proportions or thin-section analysis.
Field identification & locations
Identify by its coarse interlocking quartz–feldspar grains and scattered dark minerals; common in continental shields, mountain batholiths, and glacial gravels worldwide. A streak test is unhelpful; a fresh broken surface is more diagnostic.
