sedimentary

Smooth river pebble

Indeterminate lithology; likely fine-grained quartz-rich sandstone, siltstone, or weathered chert

AI-generated identification · may be incorrect

Rounded, water-worn, tan-gray, and dull to slightly waxy; grain size is not resolvable from the image. Likely hardness about Mohs 5–7, with no visible cleavage or crystals and specific gravity roughly 2.5–2.7.

Identified August 11, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed as a natural rock fragment and rounded by abrasion in a stream, beach, or glacial environment; its original rock may be much older than the pebble’s transport history.

Uses & applications

Usually decorative or collected; may be used in crafts, landscaping, and aquarium substrates. It has little commercial value without distinctive composition or provenance.

Geological facts

The smooth oval shape reflects repeated tumbling and abrasion, not necessarily a particular mineral identity. A close-up image, streak test, hardness test, and fresh broken surface would be needed for reliable identification.

Field identification & locations

Common in riverbeds, beaches, and gravel deposits worldwide; test hardness against steel or glass, inspect grains with magnification, and use dilute acid to check for carbonate minerals.