igneous
Quartz-rich granitic pebble
Granite or granitic gneiss; chiefly quartz (SiO₂), feldspar, and minor mica
AI-generated identification · may be incorrectCoarse, interlocking pale crystals with translucent gray quartz and white feldspar; vitreous-to-granular luster, no obvious cleavage, Mohs hardness about 6–7, specific gravity roughly 2.6–2.7. The rounded shape indicates natural abrasion or tumbling.
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Physical properties
Coarse, interlocking pale crystals with translucent gray quartz and white feldspar; vitreous-to-granular luster, no obvious cleavage, Mohs hardness about 6–7, specific gravity roughly 2.6–2.7. The rounded shape indicates natural abrasion or tumbling.
Formation & geological history
Likely formed by slow cooling of silica-rich magma deep in the crust, commonly Precambrian to Phanerozoic in age, then weathered and transported as a pebble. Strong foliation is not clearly visible, so granite is more likely than gneiss.
Uses & applications
Used as aggregate, building stone, countertops, monuments, and landscaping material; small attractive pebbles are sold for crafts and collections. This individual specimen has minimal commercial value.
Geological facts
Quartz appears glassy and gray, while feldspar forms opaque white grains; dark flecks may be biotite or amphibole. The image does not show diagnostic crystal faces or layering sufficient for a more specific identification.
Field identification & locations
Look for a speckled, interlocking texture and test hardness: it should scratch glass but not be easily scratched by a steel knife. Common worldwide, especially in eroded streams and glacial deposits.
