Rock Identifier
Limonite (FeO(OH)·nH2O) — mineral
mineral

Limonite

FeO(OH)·nH2O

AI-generated identification · may be incorrect

Hardness of 4-5.5 on the Mohs scale, yellowish-brown to dark brown color, submetallic to earthy luster, amorphous or cryptocrystalline structure, specific gravity of 2.7-4.3.

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Physical properties

Hardness of 4-5.5 on the Mohs scale, yellowish-brown to dark brown color, submetallic to earthy luster, amorphous or cryptocrystalline structure, specific gravity of 2.7-4.3.

Formation & geological history

Formed through the oxidation and weathering of iron-bearing minerals like magnetite or pyrite, typically in weathering environments and sedimentary bog deposits.

Uses & applications

Historically used as a low-grade iron ore and as a brownish-yellow pigment known as ochre.

Geological facts

Limonite is not a true distinct mineral species, but rather a mixture of related iron oxides and hydroxides like goethite and lepidocrocite.

Field identification & locations

Identified easily by its characteristic yellowish-brown streak; found worldwide in gossans above sulfide ore deposits and in residual clay soils.