sedimentary

Ironstone concretion (possibly a limonite/goethite-rich nodule)

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

AI-generated identification · may be incorrect

Irregular, knobbly, earthy-to-submetallic surface with gray-brown coloration; likely dense and opaque. Goethite is Mohs 5–5.5, with variable crystal habit and no prominent cleavage; the image alone cannot establish composition or specific gravity.

Identified October 8, 2026More sedimentary →

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At a glance

Common name: Ironstone concretion (possibly a limonite/goethite-rich nodule)
Scientific name: Iron-oxide/hydroxide concretion, commonly composed of goethite (α-FeO(OH)) and/or limonite; exact identification requires testing
Category: sedimentary
Identified: October 8, 2026
Method: Standard

AI Estimated Value

About $1–$20 USD as a common hand specimen; higher prices require confirmed unusual composition, provenance, or notable display 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

Iron-rich groundwater can deposit oxides and hydroxides around a nucleus, producing a concretion in sedimentary deposits; the specimen’s age and setting cannot be determined from the photograph.

Uses & applications

Usually collected as a geological curiosity or used as a source of iron ore where deposits are extensive; this irregular specimen has no apparent gemstone or construction use.

Geological facts

Ironstone nodules may develop rounded, lumpy shapes as minerals cement sediment together, and weathering can darken or expose rusty-brown surfaces.

Field identification & locations

A heavy feel, brown-to-reddish streak, and possible attraction to a strong magnet can support an iron-rich identification; a streak and composition test are needed to distinguish it from other iron-rich rocks or a meteorite. Ironstone occurs worldwide in sedimentary terrains.