mineral

Limonite/goethite-rich ironstone concretion (probable)

Goethite–limonite, chiefly FeO(OH)·nH₂O, possibly with hematite and manganese oxides

AI-generated identification · may be incorrect

Hardness about 4–5.5 Mohs; dark brown-black to yellow-brown weathering colors, earthy to submetallic luster, irregular concentric or botryoidal texture, and no consistent cleavage. The rounded layered form suggests an iron-oxide concretion or replacement nodule.

Identified August 28, 2026More mineral →

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At a glance

Common name: Limonite/goethite-rich ironstone concretion (probable)
Scientific name: Goethite–limonite, chiefly FeO(OH)·nH₂O, possibly with hematite and manganese oxides
Category: mineral
Identified: August 28, 2026
Method: Standard

AI Estimated Value

About $5–$30 for a typical small specimen; $30–$150+ for unusually sculptural, well-preserved, or locality-documented material.

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 when iron-bearing groundwater precipitated hydrated iron oxides around a nucleus, producing concentric growth and later weathering. Such concretions commonly form in sedimentary or weathering environments, generally at shallow geological depths; age cannot be determined from the photograph.

Uses & applications

Used historically as iron ore and pigment; attractive specimens are kept in mineral collections, though this material is generally not a jewelry stone.

Geological facts

Yellow coatings commonly reflect limonite mixtures, while harder dark surfaces may contain goethite or hematite. Identification can be tested with streak: goethite/limonite typically gives a yellow-brown to brown streak and may be weakly magnetic if magnetite is present.

Field identification & locations

Common in iron-rich soils, sedimentary beds, laterites, and mine dumps worldwide, especially around weathered iron deposits. Confirm with streak, hardness, density, magnetism, and ideally laboratory analysis; the image alone cannot establish exact species.