igneous
Rounded granitic or gneissic pebble
Likely quartz–feldspar–mica rock; exact species uncertain from the photograph
AI-generated identification · may be incorrectGray, fine- to medium-grained, granular texture with visible pale minerals and dark flecks; likely Mohs hardness 6–7, vitreous to dull luster, interlocking crystals, and no obvious cleavage as a whole rock. The rounded shape indicates water or sediment abrasion.
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Physical properties
Gray, fine- to medium-grained, granular texture with visible pale minerals and dark flecks; likely Mohs hardness 6–7, vitreous to dull luster, interlocking crystals, and no obvious cleavage as a whole rock. The rounded shape indicates water or sediment abrasion.
Formation & geological history
Probably eroded from an intrusive igneous body such as granite, then transported and rounded in a stream, beach, or glacial deposit. Its minerals commonly formed during slow cooling of magma millions to billions of years ago.
Uses & applications
Common specimens have little commercial value; granitic rocks are widely used as aggregate, paving stone, dimension stone, and landscaping material.
Geological facts
Quartz and feldspar typically provide the light gray color, while biotite or hornblende creates dark specks. The image alone cannot reliably distinguish granite from granodiorite or banded gneiss.
Field identification & locations
Look for interlocking grains, scratch resistance against glass, and separate translucent quartz, opaque feldspar, and dark mica grains; a streak test is usually unhelpful. Common worldwide, especially near granitic mountain belts and glacial or fluvial gravel deposits.
