sedimentary

Polished river pebble

Indeterminate; likely fine-grained quartz-rich sedimentary rock or weathered volcanic rock

AI-generated identification · may be incorrect

Smooth, water-rounded pebble with brown-gray coloration and a dull to weakly satin luster; likely hardness about 5–7 Mohs, with no visible cleavage or crystals. Exact composition cannot be confirmed from the photograph.

Identified August 16, 2026More sedimentary →

Explore Polished river pebble in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Shaped by abrasion in a stream, river, or beach; its original rock may be sedimentary or volcanic and could be millions to billions of years old. The rounded form reflects transport rather than a specific rock type.

Uses & applications

Primarily a decorative or craft specimen, worry stone, or landscaping pebble; not identifiable as a gem-grade material. Typical value is minimal unless locality or unusual composition is documented.

Geological facts

The dark brown surface may result from iron-oxide staining or weathering. A polished appearance can be natural from water abrasion or enhanced by tumbling.

Field identification & locations

Common worldwide in river gravels and shorelines; test a fresh surface with a steel nail and glass, and inspect with a loupe for quartz grains, volcanic texture, or layering. Acid and streak tests may further distinguish carbonate from silicate rock.