igneous
Polished/tumbled granite pebble
Granite, chiefly quartz, feldspar, and mica (variable composition)
AI-generated identification · may be incorrectHardness about 6–7 Mohs; rounded and polished, with mottled brown, gray, white, and black grains and a subdued vitreous-to-waxy luster. Coarse interlocking crystals are visible, though surface wear obscures details; no consistent cleavage as a whole rock.
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Physical properties
Hardness about 6–7 Mohs; rounded and polished, with mottled brown, gray, white, and black grains and a subdued vitreous-to-waxy luster. Coarse interlocking crystals are visible, though surface wear obscures details; no consistent cleavage as a whole rock.
Formation & geological history
Granite crystallizes slowly from silica-rich magma deep in continental crust, commonly during Precambrian to Phanerozoic mountain-building events; this specimen was later weathered, transported, and mechanically polished.
Uses & applications
Used extensively as building stone, countertops, monuments, paving, and aggregate; small polished pieces are sold as decorative stones and craft materials.
Geological facts
The light grains are commonly feldspar and quartz, while dark flecks are biotite or amphibole. Exact identification is limited because the specimen is small and highly weathered or polished.
Field identification & locations
Identify by its coarse, speckled texture, hardness, and lack of layering or bubbles; a steel knife generally does not scratch it. Common worldwide, especially in continental shields and exposed mountain batholiths.
