igneous
Polished quartz-rich feldspar rock, possibly orbicular granite
Granite or granitic pegmatite; chiefly quartz (SiO₂), feldspar, and dark biotite/amphibole
AI-generated identification · may be incorrectHardness about 6–7 Mohs; white, orange-brown, and black mottled appearance with a polished/worn surface and mostly vitreous to dull luster. Coarse interlocking crystals are suggested, but the image is insufficient for definitive identification.
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Physical properties
Hardness about 6–7 Mohs; white, orange-brown, and black mottled appearance with a polished/worn surface and mostly vitreous to dull luster. Coarse interlocking crystals are suggested, but the image is insufficient for definitive identification.
Formation & geological history
Formed by slow cooling of silica-rich magma deep in the crust, commonly during Precambrian to Phanerozoic intrusive events. The rounded form appears naturally water-worn or deliberately tumbled.
Uses & applications
Used as dimension stone, aggregate, countertops, monuments, and decorative tumbled stone; usually modest collector value unless unusually patterned or gem-quality.
Geological facts
Orange coloration commonly comes from iron-stained feldspar, while black patches may be biotite or amphibole. It could also be a feldspar-rich quartzite or another mixed silicate pebble.
Field identification & locations
Look for visible interlocking quartz and feldspar grains, a nonmetallic luster, hardness greater than glass, and no acid reaction; a streak, close-up, and scratch test would improve identification. Common in granitic terrains and stream gravels.
