sedimentary

Weathered iron-rich concretion or limonite-bearing rock

Limonite/goethite-rich concretion; limonite is an iron-oxide/hydroxide mixture, commonly dominated by goethite (FeO(OH))

AI-generated identification · may be incorrect

Hardness about 4–5.5 Mohs; dull earthy to submetallic luster, tan-brown to dark gray coloration, irregular massive texture, and no obvious cleavage. The rough cavity and rusty surface suggest weathering and iron-oxide cementation rather than a clean crystal.

Identified August 19, 2026More sedimentary →

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At a glance

Common name: Weathered iron-rich concretion or limonite-bearing rock
Scientific name: Limonite/goethite-rich concretion; limonite is an iron-oxide/hydroxide mixture, commonly dominated by goethite (FeO(OH))
Category: sedimentary
Identified: August 19, 2026
Method: Standard

AI Estimated Value

Typically $2–$20 as an ordinary specimen; distinctive forms or locality-labeled pieces may sell for roughly $25–$75.

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 an iron-rich concretion in sediment, soil, or weathered bedrock, with groundwater concentrating and oxidizing iron over geologically recent to ancient times. Exact age and host environment cannot be determined from the photograph.

Uses & applications

Used mainly as a mineral specimen, pigment source, and historically as an iron ore; generally unsuitable for construction because of its irregularity and low-grade composition.

Geological facts

Limonite commonly produces yellow, orange, and reddish-brown streaks and may coat or replace other minerals. A magnet test may show weak attraction if magnetite is present, while a streak test on unglazed porcelain can help distinguish iron oxides.

Field identification & locations

Common in weathered zones, laterites, bog-iron deposits, and sedimentary concretions worldwide. Its identity would be improved by testing streak, magnetism, density, and chemical composition; the image alone cannot confirm a specific mineral.