mineral

Weathered iron-rich concretion or limonite/goethite nodule

Limonite (largely hydrated iron oxides; commonly goethite, FeO(OH), and hematite, Fe₂O₃)

AI-generated identification · may be incorrect

Hardness about 4–5.5 Mohs; rusty yellow-brown to dark brown, earthy to dull/submetallic luster, irregular botryoidal or porous texture, and no obvious cleavage. The specimen appears rounded, weathered, and iron-stained, possibly with a small cavity or fossil-like inclusion.

Identified August 13, 2026More mineral →

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At a glance

Common name: Weathered iron-rich concretion or limonite/goethite nodule
Scientific name: Limonite (largely hydrated iron oxides; commonly goethite, FeO(OH), and hematite, Fe₂O₃)
Category: mineral
Identified: August 13, 2026
Method: Standard

AI Estimated Value

Typically $2–$20 for a small common nodule; unusual shapes or confirmed fossil-bearing specimens may reach $25–$100.

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 by oxidation and weathering of iron-bearing minerals, commonly as a soil or sedimentary concretion; age cannot be determined from the photograph and may range from recent to ancient.

Uses & applications

Used historically as an iron ore and yellow-brown pigment; attractive nodules are mainly collected as geological specimens.

Geological facts

Limonite is a field term rather than a single precisely defined mineral, because its hydrated iron-oxide mixture varies. Goethite-rich material may form botryoidal surfaces and stalactitic cavities.

Field identification & locations

Identify by its rusty color, heavy feel, earthy appearance, and potential reddish-yellow streak; a magnet may show weak attraction if magnetite is present. Common in weathered iron deposits, laterites, stream gravels, and sedimentary rocks.