sedimentary

Iron-rich concretion or weathered ironstone

Goethite–hematite-bearing ironstone; identification is uncertain from appearance alone

AI-generated identification · may be incorrect

Rusty red-brown, earthy to dull luster, irregular porous texture, and rounded water-worn shape; likely hardness about 4–6 Mohs, with variable density and weak or absent cleavage. Dark patches may be manganese oxides or concentrated iron minerals.

Identified August 26, 2026More sedimentary →

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At a glance

Common name: Iron-rich concretion or weathered ironstone
Scientific name: Goethite–hematite-bearing ironstone; identification is uncertain from appearance alone
Category: sedimentary
Identified: August 26, 2026
Method: Standard

AI Estimated Value

$1–$15 for a common unattributed specimen; approximately $20–$75 if unusually shaped, locality-labeled, or strongly magnetic.

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

Formed by precipitation and cementation of iron oxides/hydroxides in sediment, soil, or weathering zones; commonly Cenozoic to recent, though ironstone can occur at many geological ages.

Uses & applications

Used as iron ore when sufficiently concentrated and historically as a red-brown pigment; otherwise mainly a teaching or collecting specimen, typically with little commercial value.

Geological facts

The red color generally reflects hematite or iron-rich clay, while yellow-brown components may be goethite or limonite. A streak test is more diagnostic than surface color.

Field identification & locations

Common in lateritic soils, river gravels, deserts, and sedimentary ironstone beds worldwide. Test an inconspicuous area: hematite gives a red to reddish-brown streak; goethite gives yellow-brown, and a magnet may detect associated magnetite.