mineral

Goethite

Goethite (FeO(OH))

Hardness: 5-5.5 (Mohs scale), Color: Dark brown to black with iridescent or metallic luster, Crystal Structure: Orthorhombic, Streak: Brownish-yellow.

Hardness: 5-5
Streak: Brownish-yellow

Identified June 21, 2026More mineral →

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Physical properties

Hardness: 5-5.5 (Mohs scale), Color: Dark brown to black with iridescent or metallic luster, Crystal Structure: Orthorhombic, Streak: Brownish-yellow.

Formation & geological history

Formed as a weathering product of iron-bearing minerals in soil and oxidation zones of ore deposits. Can also form by direct inorganic or biogenic precipitation in marine and spring waters.

Uses & applications

An important iron ore. Often used as a pigment (ochre). Collected for its unique botryoidal (grape-like) habits and iridescent surface coatings.

Geological facts

Named after Johann Wolfgang von Goethe, the German polymath. It is a primary component of iron rust and bog iron ore.

Field identification & locations

Identified by its yellow-brown streak, metallic to sub-metallic luster, and frequent association with limonite. Common in Australia, Brazil, and the USA (Great Lakes region).