sedimentary

Ironstone concretion (likely goethite/limonite-rich)

Iron-oxide/hydroxide-rich concretion, commonly goethite (α-FeO(OH)) and limonite; exact identification requires testing

AI-generated identification · may be incorrect

Opaque, rounded, mottled ochre-yellow to brown, with earthy to submetallic luster and rough texture. Goethite has Mohs hardness 5–5.5; concretion hardness varies, and crystal structure is not identifiable from the image.

Identified October 10, 2026More sedimentary →

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At a glance

Common name: Ironstone concretion (likely goethite/limonite-rich)
Scientific name: Iron-oxide/hydroxide-rich concretion, commonly goethite (α-FeO(OH)) and limonite; exact identification requires testing
Category: sedimentary
Identified: October 10, 2026
Method: Standard

AI Estimated Value

Typically about $1–$10 as a small common specimen; higher value would depend on unusual form, locality, or confirmed mineral content.

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 minerals cemented sediment grains or accumulated around a nucleus during groundwater movement; age and precise setting cannot be determined visually.

Uses & applications

Usually collected as a geological curiosity; ironstone has limited use as iron ore where iron content and deposit size are sufficient.

Geological facts

Yellow-brown staining is typical of hydrated iron oxides, which form through oxidation and weathering of iron-bearing minerals.

Field identification & locations

Look for a dense, earthy brown-to-ochre object, often with rusty staining; confirm with streak, hardness, and composition tests. Ironstone occurs in many sedimentary regions worldwide.