igneous
Quartz–feldspar pegmatite (likely granite fragment)
Granitoid/pegmatitic rock, chiefly quartz (SiO₂) and feldspar, with dark mica or amphibole
AI-generated identification · may be incorrectHardness about 6–7; cream-white with gray-brown patches, vitreous to pearly luster, coarse interlocking crystals, and no obvious foliation. The rounded shape appears naturally weathered or tumbled; exact identification is limited by the photograph.
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Physical properties
Hardness about 6–7; cream-white with gray-brown patches, vitreous to pearly luster, coarse interlocking crystals, and no obvious foliation. The rounded shape appears naturally weathered or tumbled; exact identification is limited by the photograph.
Formation & geological history
Formed when silica-rich magma cooled slowly underground, allowing large crystals to grow; commonly Precambrian to Phanerozoic in age. Weathering and transport likely rounded this specimen.
Uses & applications
Used as aggregate, dimension stone, decorative rock, and a source of feldspar, quartz, and mica; attractive pieces may be collected but are generally low value.
Geological facts
The pale material is likely feldspar and quartz, while dark flakes or patches may be biotite mica or hornblende. Pegmatites can host tourmaline, beryl, and other collectible minerals.
Field identification & locations
Look for visible interlocking crystals, glassy quartz, blocky feldspar cleavage, and black mica flakes; a glass-scratch test can help, since quartz scratches glass. Common in granitic terrains worldwide, including the Appalachians, Scandinavia, and western North America.
