Limonite/Goethite Gossan

Physical Properties

Hardness: 4-5.5; Color: Yellowish-brown to dark brown; Luster: Dull/Earthy; Crystal Structure: Amorphous or microcrystalline; Cleavage: None; Specific Gravity: 2.7-4.3

Formation & Geological History

Formed as a secondary oxidation product of iron-bearing minerals, often as a 'gossan' or iron hat atop ore deposits. Primarily occurs in oxygen-rich subterranean environments.

Uses & Applications

Historically used as an iron ore; currently used as a pigment (yellow ochre) and occasionally in mineral specimen collecting.

Geological Facts

Limonite is not a single mineral but a mixture of hydrated iron oxides, primarily goethite. It was a major source of iron for various civilizations during the Iron Age.

Field Identification & Locations

Identify by its brownish-yellow streak test and earthy texture. Commonly found in oxidized zones of ore deposits globally. Collectors should look for its distinctive mustard-yellow to rust color.

Identified on: 5/8/2026

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