mineral

Limonite with Hematite

Hydrated iron(III) oxide-hydroxide with variable composition (FeO(OH)·nH2O)

Hardness: 4-5.5 (Mohs); Color: Dark brown to yellowish-orange; Luster: Dull or earthy; Crystal structure: Amorphous; Cleavage: None; Specific gravity: 2.7-4.3

Hardness: 4-5
Color: Dark brown to yellowish-orange
Luster: Dull or earthy

Identified June 13, 2026More mineral →

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Physical properties

Hardness: 4-5.5 (Mohs); Color: Dark brown to yellowish-orange; Luster: Dull or earthy; Crystal structure: Amorphous; Cleavage: None; Specific gravity: 2.7-4.3

Formation & geological history

Formed through the chemical weathering of iron-rich minerals such as pyrite, magnetite, or biotite. It is typically found in oxidation zones of ore deposits or as a secondary mineral in sedimentary rock layers.

Uses & applications

Historically used as an iron ore; currently used primarily as a pigment/ocher for paints and dyes. In geological prospecting, it is used as a 'gossan' indicator to find deeper metal deposits.

Geological facts

Limonite is not a true mineral but a mixture of various hydrated iron oxides. It was a major source of iron for early civilizations and was used by prehistoric humans as a cave painting pigment.

Field identification & locations

Identify in the field by its distinct yellow-brown streak, earthy texture, and association with rust-colored staining on surrounding rocks. Found globally in weathered terrains and swampy 'bog iron' areas.

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