mineral

Goethite / Limonite Gossan

Goethite, FeO(OH)

Hardness: 5-5.5; Color: Brownish-black, yellow-brown, or reddish; Luster: Submetallic, silky, or earthy; Crystal Structure: Orthorhombic; Specific Gravity: 3.3-4.3.

Hardness: 5-5
Color: Brownish-black, yellow-brown, or reddish
Luster: Submetallic, silky, or earthy

Identified June 1, 2026More mineral →

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Physical properties

Hardness: 5-5.5; Color: Brownish-black, yellow-brown, or reddish; Luster: Submetallic, silky, or earthy; Crystal Structure: Orthorhombic; Specific Gravity: 3.3-4.3.

Formation & geological history

Formed as a weathering product of iron-rich minerals in the oxidation zone of ore deposits. Often part of a 'gossan' or iron hat on top of a sulfide deposit.

Uses & applications

Historically used as an iron ore (brown hematite) and as a pigment (ochre). Collected for geological study of mineral oxidation zones.

Geological facts

Goethite is named after the German polymath Johann Wolfgang von Goethe. It is the main component of bog iron ore and is also common on the surface of Mars.

Field identification & locations

Identified by its yellowish-brown streak, botryoidal (grape-like) or earthy habit, and association with rusty weathering. Found globally in iron-rich weathering environments.