sedimentary

Water-worn river pebble

Unidentified fine-grained siliciclastic rock; likely sandstone or siltstone

AI-generated identification · may be incorrect

Rounded, smooth, tan-to-dark-gray with a subtle band; likely Mohs hardness about 3–7 depending on composition, dull to weakly lustrous, and no visible crystal faces or cleavage. The photograph is insufficient to determine its exact mineral composition or specific gravity.

Identified October 16, 2026More sedimentary →

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Physical properties

Formation & geological history

A pre-existing rock fragment was rounded by abrasion during transport in water; its original formation age and setting cannot be determined from the image.

Uses & applications

Primarily a natural-history or decorative specimen; similar pebbles may be used in landscaping or crafts.

Geological facts

The color boundary may reflect different layers or mineral staining, but cannot be identified confidently from appearance alone.

Field identification & locations

Its smooth, rounded shape is consistent with water transport. A fresh break, hardness test, and close inspection of grains would help distinguish sandstone, siltstone, and other pebble types.