mineral

Limonite (Gozzany Iron)

Limonite (FeO(OH)·nH2O)

Hardness: 4.0 to 5.5 on Mohs scale; Color: Yellowish-brown to dark brown; Luster: Dull to earthy; Crystal structure: Amorphous; Cleavage: None; Specific gravity: 2.7 to 4.3.

Hardness: 4
Color: Yellowish-brown to dark brown
Luster: Dull to earthy

Identified March 22, 2026More mineral →

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Physical properties

Hardness: 4.0 to 5.5 on Mohs scale; Color: Yellowish-brown to dark brown; Luster: Dull to earthy; Crystal structure: Amorphous; Cleavage: None; Specific gravity: 2.7 to 4.3.

Formation & geological history

Formed as a secondary material through the oxidation and weathering of iron-rich mineral ores like pyrite, magnetite, and siderite. Often found in swampy environments (bog iron) or in the weathered zone above primary sulfide deposits.

Uses & applications

Historically used as a major source of iron ore; currently used as a pigment (ochre) for paints and dyes. In jewelry, it is sometimes used as a minor collector's stone or as a component in tiger's eye formation.

Geological facts

Limonite is not a 'true' mineral but a mixture of hydrated iron oxide minerals. It has been used as a pigment by humans for at least 16,000 years, found in the cave paintings at Lascaux, France.

Field identification & locations

Identify by its distinctive yellow-brown streak (powder color), which separates it from hematite (red streak). It is often found in 'rusty' soil or as coatings on other rocks in iron-rich terrains. It is common worldwide in sedimentary deposits.