mineral

Limonite

FeO(OH)·nH2O

Hardness: 4 to 5.5 on the Mohs scale. Color: Brown, yellowish-brown, or ochre-yellow. Luster: Earthy, submetallic, or silky. Crystal structure: Amorphous or microcrystalline, typically forming as concretionary, mammillary, or earthy masses. Specific gravity: 2.7 to 4.3.

Hardness: 4 to 5
Color: Brown, yellowish-brown, or ochre-yellow
Luster: Earthy, submetallic, or silky

Identified August 7, 2026More mineral →

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Physical properties

Formation & geological history

Forms as an alteration product of other iron-rich minerals such as magnetite and pyrite, typically in weathering environments, bogs, and sedimentary settings.

Uses & applications

Historically used as a low-grade iron ore and as an earthy yellow pigment (ochre) for paints and ceramics.

Geological facts

Limonite is not a single distinct mineral species, but rather a mixture of related hydrated iron oxides and hydroxides, most commonly goethite and lepidocrocite.

Field identification & locations

Can be identified in the field by its characteristic yellowish-brown streak, earthy texture, and association with weathered iron deposits. Found worldwide.