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

Limonite

FeO(OH)•nH2O

AI-generated identification · may be incorrect

Hardness of 4 to 5.5 on the Mohs scale, yellowish-brown to dark brown color, submetallic to earthy luster, amorphous crystal structure with no distinct cleavage, and a specific gravity around 2.7 to 4.3.

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Physical properties

Hardness of 4 to 5.5 on the Mohs scale, yellowish-brown to dark brown color, submetallic to earthy luster, amorphous crystal structure with no distinct cleavage, and a specific gravity around 2.7 to 4.3.

Formation & geological history

Formed through the secondary alteration and weathering of other iron-bearing minerals in oxidizing environments.

Uses & applications

Historically used as a pigment (ochre) and as a minor ore of iron.

Geological facts

Limonite is not a true distinct mineral species, but rather a mixture of related hydrated iron oxide minerals like goethite and akaganeite.

Field identification & locations

Identified easily by its characteristic yellowish-brown streak; commonly found in iron-rich gossans and sedimentary deposits worldwide.