mineral

Limonite

Limonite (Hydrous iron oxides, predominantly Goethite FeO(OH)·nH2O)

Hardness: 4 to 5.5; Color: Yellowish-brown to dark brown; Luster: Dull, earthy, or submetallic; Crystal Structure: Amorphous or microcrystalline; Streak: Yellowish-brown; Specific Gravity: 2.7 to 4.3.

Hardness: 4 to 5
Color: Yellowish-brown to dark brown
Luster: Dull, earthy, or submetallic

Identified April 1, 2026More mineral →

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Physical properties

Formation & geological history

Secondary mineral formed by the oxidation and hydration of iron-rich minerals (like pyrite or magnetite) in weathering zones or sedimentary deposits.

Uses & applications

Historically used as an ore of iron; widely used as a natural pigment (ochre) in paints, dyes, and cosmetics; occasionally used in metallurgy.

Geological facts

Limonite is not a true mineral species but a field term for unidentified hydrous iron oxides. It has been used as a pigment since prehistoric times, notably in Paleolithic cave paintings.

Field identification & locations

Identify by its characteristic yellowish-brown streak and lack of cleavage. It is commonly found in 'gossans' (weathered iron caps over ore deposits) and in bog iron deposits.

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