sedimentary

Rounded brown river pebble

Indeterminate lithic clast; possibly weathered sandstone or fine-grained volcanic rock

AI-generated identification · may be incorrect

Fine-grained, opaque, brown and weakly speckled with a dull earthy luster; likely hardness about 5–7 Mohs, with no visible cleavage or crystals. Rounded shape and smooth surface indicate abrasion by moving water or sediment.

Identified August 28, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed from an older rock and transported, weathered, and polished in a stream, beach, or glacial deposit; its original geological age cannot be determined from the photograph.

Uses & applications

Primarily a decorative or educational specimen; comparable pebbles have little commercial value and are generally unsuitable for jewelry unless cut or polished.

Geological facts

The uniformly rounded triangular form reflects differential abrasion and natural fracture resistance. A streak, hardness, acid, and grain-texture examination would be needed for reliable identification.

Field identification & locations

Common in river gravels, beaches, and alluvial deposits worldwide. Look for grain size, layering, visible quartz, vesicles, or reaction to dilute hydrochloric acid to distinguish sandstone, volcanic rock, and carbonate rock.