sedimentary

Rounded sandstone or quartz-rich river cobble

Indeterminate lithic sandstone; chiefly quartz (SiO₂) with feldspar and iron-oxide/calcite cement

AI-generated identification · may be incorrect

Fine- to medium-grained, tan-gray, dull to slightly earthy luster, rounded and water-worn with porous weathered patches. Approximate hardness 6–7 where quartz-rich; no obvious cleavage, with granular texture and likely specific gravity around 2.3–2.7.

Identified August 28, 2026More sedimentary →

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At a glance

Common name: Rounded sandstone or quartz-rich river cobble
Scientific name: Indeterminate lithic sandstone; chiefly quartz (SiO₂) with feldspar and iron-oxide/calcite cement
Category: sedimentary
Identified: August 28, 2026
Method: Standard

AI Estimated Value

Usually $1–$10 as a common specimen; up to roughly $10–$30 if unusually attractive, locality-labeled, or curated.

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 a sedimentary sandstone cobble eroded from bedrock and rounded by stream or shoreline transport; its exact depositional age and source cannot be determined from the photograph. Cementation and later weathering produced the compact, pitted surface.

Uses & applications

Common sandstone is used as aggregate, building stone, paving, and landscaping material; an ordinary cobble has little commercial or jewelry value.

Geological facts

The rounded shape indicates prolonged abrasion during transport, while darker streaks may reflect iron oxides, clay, or mineral-filled fractures. A fresh broken surface would reveal the grain size and cement more reliably than the weathered exterior.

Field identification & locations

Likely found in river gravels, beaches, glacial deposits, and landscaping stone. Confirm with a hand lens, dilute hydrochloric-acid test for calcite cement, and a scratch test; exact identification requires a fresh surface or laboratory analysis.