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

Limonite

FeO(OH)·nH2O

Hardness: 4 to 5.5 on the Mohs scale. Color: yellowish-brown, brown, to dark brown. Luster: earthy, submetallic, or silky. Crystal structure: amorphous (usually massive, botryoidal, or stalactitic habits). Cleavage: none. Specific gravity: 2.7 to 4.3.

Hardness
4 to 5
Color
yellowish-brown, brown, to dark brown
Luster
earthy, submetallic, or silky
Identified More mineral
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Physical properties

Hardness: 4 to 5.5 on the Mohs scale. Color: yellowish-brown, brown, to dark brown. Luster: earthy, submetallic, or silky. Crystal structure: amorphous (usually massive, botryoidal, or stalactitic habits). Cleavage: none. Specific gravity: 2.7 to 4.3.

Formation & geological history

Formed as a secondary mineral resulting from the oxidation and weathering of iron-bearing minerals, commonly found in gossans and sedimentary iron deposits.

Uses & applications

Historically used as a low-grade iron ore, as a yellow pigment (ochre), and collected as a mineral specimen.

Geological facts

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

Field identification & locations

Can be identified by its characteristic yellowish-brown to brownish streak and earthy appearance. Found globally where iron deposits undergo weathering.