sedimentary

Rounded red-brown ironstone cobble

Ferruginous sandstone or ironstone; commonly quartz grains cemented by iron oxides such as hematite and goethite

AI-generated identification · may be incorrect

Opaque, reddish-brown, with a rough, fine-grained surface and rounded shape. Likely hardness around 5–7 Mohs if quartz-rich; no obvious cleavage. Exact composition and density cannot be confirmed from the image.

Identified October 13, 2026More sedimentary →

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At a glance

Common name: Rounded red-brown ironstone cobble
Scientific name: Ferruginous sandstone or ironstone; commonly quartz grains cemented by iron oxides such as hematite and goethite
Category: sedimentary
Identified: October 13, 2026
Method: Standard

AI Estimated Value

About $5–$30 USD for an ordinary cobble; higher value would require distinctive features, verified provenance, or collectible quality.

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 formed as iron-rich sediment or sandstone cemented by iron oxides, then rounded by prolonged water transport. Its geological age and precise formation environment cannot be determined visually.

Uses & applications

Usually a decorative or collectible field specimen; iron-rich stone may also be used as low-grade iron ore or aggregate where composition and quality warrant.

Geological facts

Iron oxides produce the red-brown color, and rounded edges typically indicate abrasion during transport or weathering.

Field identification & locations

Look for a dense, earthy-red to brown stone with iron staining; a streak, magnetism test, or hardness test can help distinguish ironstone from other cobbles. Such material occurs in sedimentary deposits worldwide.