igneous
Weathered granitic pebble
Likely granite or granodiorite, composed mainly of quartz, feldspar, and mica/amphibole
AI-generated identification · may be incorrectHardness about 6–7 Mohs; pale gray to cream with dark gray mineral flecks, granular texture, and dull to weakly vitreous luster. Interlocking crystals are visible, with no obvious cleavage at specimen scale; specific gravity commonly 2.63–2.75.
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Physical properties
Hardness about 6–7 Mohs; pale gray to cream with dark gray mineral flecks, granular texture, and dull to weakly vitreous luster. Interlocking crystals are visible, with no obvious cleavage at specimen scale; specific gravity commonly 2.63–2.75.
Formation & geological history
An intrusive igneous rock that crystallized slowly from silica-rich magma deep in the crust, commonly during Precambrian to Phanerozoic mountain-building events; the rounded shape indicates later stream or beach abrasion and weathering.
Uses & applications
Used widely as crushed aggregate, building stone, paving, monuments, and countertops; this small pebble has primarily educational or decorative value rather than gem value.
Geological facts
The darker streaks may reflect biotite mica or hornblende, while the pale groundmass is feldspar and quartz. Exact identification requires a loupe, hardness testing, and ideally thin-section or chemical analysis.
Field identification & locations
Common worldwide in continental crust and river gravels. Look for visible interlocking grains, pink/white feldspar, translucent gray quartz, and dark mica; granite is typically harder than a steel knife and does not fizz with dilute acid.
