sedimentary

Rounded yellow-brown cobble

Likely weathered sandstone or quartz-rich conglomeratic clast; exact identification requires a fresh surface and testing

AI-generated identification · may be incorrect

Fine- to medium-grained, dull earthy luster, rounded by transport, with yellow-brown iron-oxide staining and gray patches. Estimated hardness 5–7 Mohs if sandstone/quartz-rich; cleavage absent, specific gravity approximately 2.5–2.7.

Identified August 19, 2026More sedimentary →

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At a glance

Common name: Rounded yellow-brown cobble
Scientific name: Likely weathered sandstone or quartz-rich conglomeratic clast; exact identification requires a fresh surface and testing
Category: sedimentary
Identified: August 19, 2026
Method: Standard

AI Estimated Value

$0–$10 as an ordinary cobble; potentially $20–$100+ if testing reveals attractive jasper, agate, fossil content, or unusual provenance.

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 naturally weathered and stream- or glacial-transported sedimentary cobble, with coloration from oxidation of iron-bearing minerals. Its depositional age cannot be determined from the photograph.

Uses & applications

Primarily a landscaping, educational, or collection specimen; material of this appearance has little industrial or jewelry value unless it proves to be an unusual fossil, jasper, or agate.

Geological facts

The smooth rounded form indicates prolonged abrasion or weathering. The dark surrounding material appears to be pavement or another rock surface, not part of the specimen.

Field identification & locations

Look for visible sand grains, bedding, or cement to confirm sandstone; a glassy fracture and strong quartz content suggest quartzite, while waxy red-yellow color suggests jasper. Commonly found in river gravels, glacial deposits, and eroded road cuts.