mineral

Limonite

FeO(OH)·nH2O

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

Identified July 29, 2026More mineral →

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Physical properties

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

Formation & geological history

Formed through the weathering and oxidation of iron-rich minerals and rocks, typically found in gossans, bog iron deposits, and sedimentary environments.

Uses & applications

Historically used as a pigment (ochre), as an iron ore, and occasionally as a minor ornamental stone by collectors.

Geological facts

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

Field identification & locations

Can be identified easily in the field by its characteristic yellowish-brown or brownish-yellow streak and earthy appearance. Found worldwide wherever iron-bearing rocks weather.