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, and amorphous crystal structure.

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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, and amorphous crystal structure.

Formation & geological history

Forms as a secondary mineral resulting from the weathering and oxidation of various iron-bearing minerals in hydrothermal veins or sedimentary 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 hydrated iron oxides like goethite and lepidocrocite.

Field identification & locations

Easily identified by its characteristic yellowish-brown streak; found worldwide in gossans above iron ore deposits.