sedimentary

Iron-rich sandstone or limonite/goethite concretion

Ferruginous sandstone with limonite–goethite (hydrated iron oxides), possibly a weathered ironstone concretion

AI-generated identification · may be incorrect

Brown to reddish-brown, earthy to dull luster, irregular layered/porous texture, and no visible crystal faces; likely Mohs hardness about 4–6, with variable specific gravity and weak to moderate magnetism if magnetite is present.

Identified September 4, 2026More sedimentary →

Explore Iron-rich sandstone or limonite/goethite concretion in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

At a glance

Common name: Iron-rich sandstone or limonite/goethite concretion
Scientific name: Ferruginous sandstone with limonite–goethite (hydrated iron oxides), possibly a weathered ironstone concretion
Category: sedimentary
Identified: September 4, 2026
Method: Standard

AI Estimated Value

About $1–$15 as a common hand specimen; attractive, unusual, or locality-labeled examples may sell for roughly $20–$50.

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

Forms when iron-bearing groundwater cements sand or replaces sediment, commonly through oxidation and weathering near the surface; age cannot be determined from the photograph and may range from recent soil formation to ancient sedimentary deposits.

Uses & applications

Mostly a geological or educational specimen; iron-rich material can be an iron ore when sufficiently concentrated, but this small piece has little practical or gem value.

Geological facts

The rusty coloration is produced mainly by ferric iron minerals such as goethite and limonite; darker areas may contain hematite or magnetite.

Field identification & locations

Identify with a streak test: yellow-brown streak suggests goethite/limonite, while red-brown suggests hematite; a magnet test and acid test can further distinguish associated minerals. Common in weathered sedimentary terrains and ironstone deposits worldwide.