mineral

Limonite Concretion

Limonite (FeO·nH2O)

Hardness: 4 to 5.5 on the Mohs scale. Color: Yellowish-brown, dark brown, or reddish-brown. Luster: Earthy to submetallic. Crystal structure: Amorphous, typically forms as botryoidal, mammillary, or stalactitic masses and concretions. Cleavage: None.

Hardness: 4 to 5
Color: Yellowish-brown, dark brown, or reddish-brown
Luster: Earthy to submetallic

Identified August 4, 2026More mineral →

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Physical properties

Formation & geological history

Formed through the secondary alteration and weathering of other iron-bearing minerals and rocks, frequently found in sedimentary environments or as gossans above sulfide ore deposits.

Uses & applications

Used historically as a source of iron ore, as a yellow and brown pigment (ochre) for paints and dyes, and valued by mineral collectors for unusual botryoidal and concretionary shapes.

Geological facts

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

Field identification & locations

Easily identified by its characteristic yellowish-brown streak, earthy luster, and brownish-orange weathering crusts. Found worldwide in oxidized iron deposits and weathering zones.