igneous
Rounded quartz-rich pebble, likely granite or granitic gneiss
Granite-derived granitoid; mainly quartz (SiO₂), feldspar, and minor mica
AI-generated identification · may be incorrectLight gray, fine-to-medium crystalline, dull to weakly vitreous luster, with no obvious cleavage on the worn surface; estimated Mohs hardness 6–7 and specific gravity about 2.6–2.7. Its rounded shape and smooth surface indicate water or beach abrasion, with possible surface weathering or coating obscuring grains.
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Physical properties
Light gray, fine-to-medium crystalline, dull to weakly vitreous luster, with no obvious cleavage on the worn surface; estimated Mohs hardness 6–7 and specific gravity about 2.6–2.7. Its rounded shape and smooth surface indicate water or beach abrasion, with possible surface weathering or coating obscuring grains.
Formation & geological history
Likely weathered from an ancient continental granite or gneiss and transported by a stream, wave action, or glacial sediment; the original rock may be hundreds of millions to billions of years old. Exact identification requires a fresh break or magnification.
Uses & applications
Common granitic pebbles are used as landscaping stone, aggregate, and decorative tumbled stones; this small specimen has minimal commercial value.
Geological facts
The pale color suggests abundant quartz and feldspar, while the rounded form reflects prolonged abrasion rather than crystal growth. It may also be a quartz-rich metamorphic pebble, such as quartzite, if the grains interlock tightly.
Field identification & locations
Look for visible glassy quartz, opaque white or pink feldspar, and dark mica; a streak test is unhelpful, while a steel file or glass scratch can estimate hardness. Common in beaches, river gravels, glacial deposits, and construction aggregate.
