mineral

Weathered iron-rich rock, possibly limonite/goethite or ironstone

Limonite (hydrated iron oxides; commonly goethite, FeO(OH), with hematite and/or magnetite)

AI-generated identification · may be incorrect

Brown-gold to black, earthy and dull to submetallic luster, porous and irregular; typically Mohs 4–5.5, with no obvious cleavage and variable density. The metallic-looking golden patches may be iron-oxide staining or weathered sulfide minerals.

Identified August 13, 2026More mineral →

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Physical properties

Formation & geological history

Forms through oxidation and weathering of iron-bearing rocks or sulfide ores, often producing a porous gossan; generally geologically young as a weathering product, though the source rock may be ancient.

Uses & applications

Used historically as iron ore and pigment; attractive pieces are collected, but it is rarely used in jewelry or construction.

Geological facts

Limonite is not a single pure mineral but a field term for mixed hydrated iron oxides. A reddish-brown streak and attraction to a magnet, if present, help distinguish iron-rich material.

Field identification & locations

Common in oxidized ore zones worldwide, especially above copper, gold, and iron deposits. Test streak on unglazed porcelain, magnetism, and hardness; identification from the photograph is provisional.