sedimentary

Weathered graywacke or sandstone cobble

Lithic/feldspathic sandstone; exact identification requires a fresh break or thin section

AI-generated identification · may be incorrect

Gray-brown, fine- to medium-grained, dull and strongly weathered, with poorly visible bedding and possible quartz/feldspar grains; typical hardness about 6–7, no obvious cleavage, and moderate density around 2.5–2.7 g/cm³.

Identified August 10, 2026More sedimentary →

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At a glance

Common name: Weathered graywacke or sandstone cobble
Scientific name: Lithic/feldspathic sandstone; exact identification requires a fresh break or thin section
Category: sedimentary
Identified: August 10, 2026
Method: Standard

AI Estimated Value

Usually $1–$10 as an ordinary cobble; up to roughly $10–$30 if locally significant, unusually textured, or part of a documented collection.

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

Likely lithified sand deposited in a river, beach, or submarine-fan environment, then compacted and cemented; age cannot be determined from the photograph and may range from Paleozoic to recent geological settings.

Uses & applications

Common sandstone is used as aggregate, building or paving stone, and occasionally as a decorative specimen; this rounded cobble has little commercial value.

Geological facts

The rounded shape indicates prolonged transport or wave abrasion, while the rough, rusty surface reflects chemical weathering of iron-bearing minerals or cement.

Field identification & locations

Look for visible quartz grains, gritty texture, and scratching with a steel file; dilute hydrochloric acid should produce little or no fizz unless carbonate cement is present. Common in streambeds, beaches, and glacial deposits.