sedimentary

Rounded river pebble, likely fine-grained sandstone or siltstone

Indeterminate clastic sedimentary rock; possibly quartz-rich sandstone

AI-generated identification · may be incorrect

Fine-grained, tan-gray, matte and strongly rounded, with a slightly granular surface; likely Mohs hardness 5–7, no visible cleavage, and low-to-moderate specific gravity. The dark circular area may be natural iron staining, a weathered inclusion, or surface coating.

Identified August 21, 2026More sedimentary →

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At a glance

Common name: Rounded river pebble, likely fine-grained sandstone or siltstone
Scientific name: Indeterminate clastic sedimentary rock; possibly quartz-rich sandstone
Category: sedimentary
Identified: August 21, 2026
Method: Standard

AI Estimated Value

Usually $1–$10 as an ordinary pebble; up to about $10–$30 if unusually attractive, locally significant, or sold as a polished/geological specimen.

Not an official valuation

AI estimate for general interest only — not an appraisal. Actual value depends on condition, provenance, and market demand. Verify with a professional before buying, selling, or insuring.

This identification was generated by AI and may contain errors. Verify important details before relying on them — and never use an AI result to judge whether a specimen is safe to handle. Read the full disclaimer

Physical properties

Formation & geological history

Probably formed from compacted and cemented sand or silt, then smoothed by prolonged water or shoreline abrasion. Exact geological age and composition cannot be determined reliably from the photograph.

Uses & applications

Primarily a decorative or collected pebble; sandstone may be used as building or paving stone, but this small specimen has no practical industrial value.

Geological facts

Its rounded shape indicates substantial transport or wave abrasion. The apparent central bump may be a concretion, mineral inclusion, or simply an irregular weathered surface.

Field identification & locations

Look for visible grains, bedding, acid reaction, and streak; a hand lens and hardness test are useful, while laboratory tests are needed for firm identification. Similar pebbles occur in river gravels, beaches, and glacial deposits worldwide.