igneous
Tumbled granite or granitic gneiss
Quartz–feldspar–mica granitoid; likely biotite granite, possibly foliated gneiss
AI-generated identification · may be incorrectCoarse, interlocking grains of pale pink/white feldspar, gray translucent quartz, and dark biotite or amphibole; vitreous-to-pearly luster, massive texture, Mohs hardness about 6–7, no obvious cleavage as a whole, and specific gravity roughly 2.6–2.8.
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Physical properties
Coarse, interlocking grains of pale pink/white feldspar, gray translucent quartz, and dark biotite or amphibole; vitreous-to-pearly luster, massive texture, Mohs hardness about 6–7, no obvious cleavage as a whole, and specific gravity roughly 2.6–2.8.
Formation & geological history
Formed when silica-rich magma crystallized slowly deep in the continental crust, commonly during Precambrian to younger mountain-building events; if gneissic, it was later altered by high-grade metamorphism.
Uses & applications
Used widely as dimension stone, countertops, monuments, aggregate, and landscaping rock; attractive polished pieces are collected but generally have modest value.
Geological facts
The pink color usually comes from potassium feldspar, while dark flakes are commonly biotite mica or hornblende. The rounded, smooth surface indicates natural abrasion or tumbling.
Field identification & locations
Common worldwide, especially in continental shields and mountain belts; identify by visible quartz, feldspar, and dark mafic minerals in a granular mosaic. A streak, glass-scratch test, and close inspection for foliation can help distinguish granite from gneiss.
