mineral

Goethite

Goethite (FeO(OH))

AI-generated identification · may be incorrect

Hardness: 5-5.5 (Mohs), Color: brownish-black, yellowish-brown, Luster: Adamantine to dull, Crystal structure: Orthorhombic, Cleavage: Perfect on {010}, Streak: Brownish-yellow

Hardness: 5-5
Streak: Brownish-yellow

Identified July 7, 2026More mineral →

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Physical properties

Hardness: 5-5.5 (Mohs), Color: brownish-black, yellowish-brown, Luster: Adamantine to dull, Crystal structure: Orthorhombic, Cleavage: Perfect on {010}, Streak: Brownish-yellow

Formation & geological history

Formed usually through the weathering of other iron-rich minerals like pyrite or magnetite. It is a common component of soil and bog iron ore, creating under oxidizing conditions.

Uses & applications

Historically used as an iron ore; currently used as a pigment (brown ochre) and as a mineral specimen for collectors.

Geological facts

Named after the German polymath and poet Johann Wolfgang von Goethe. It is a primary component of rust and exists on the planet Mars.

Field identification & locations

Identified in the field by its distinct yellowish-brown streak and botryoidal (grape-like) or massive habit. Found worldwide in weathered zones of iron deposits.