igneous
Tumbled granite (likely granitic gneiss)
Granite; primarily quartz (SiO₂), feldspar, and mica, possibly with metamorphic foliation
AI-generated identification · may be incorrectCoarse-grained, pale gray-green specimen with black mica/amphibole and white feldspar; vitreous to dull luster, interlocking crystals, no obvious cleavage as a whole rock, Mohs hardness about 6–7, density roughly 2.6–2.8 g/cm³.
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Physical properties
Coarse-grained, pale gray-green specimen with black mica/amphibole and white feldspar; vitreous to dull luster, interlocking crystals, no obvious cleavage as a whole rock, Mohs hardness about 6–7, density roughly 2.6–2.8 g/cm³.
Formation & geological history
Formed by slow cooling of silica-rich magma deep in the crust, commonly during Precambrian to Phanerozoic mountain-building; if gneissic, it was later altered by high-grade metamorphism.
Uses & applications
Used widely as dimension stone, countertops, monuments, aggregate, and landscaping rock; polished pieces are popular inexpensive geological specimens.
Geological facts
The rounded surface indicates tumbling or natural abrasion. Dark grains are likely biotite or hornblende, while translucent grains may be quartz.
Field identification & locations
Identify it by visible interlocking light and dark grains, substantial weight, and lack of bubbles or glassy uniformity; common worldwide in continental mountain belts. A closer view or streak, acid, and hardness tests would refine identification.
