mineral

Goethite/Limonite Iron Ore Node

Goethite (FeO(OH)) or Limonite (mixture of hydrated iron oxides)

AI-generated identification · may be incorrect

Hardness: 5.0 to 5.5; Color: dark brown to yellowish-brown; Luster: submetallic or dull; Crystal structure: orthorhombic (often massive or botryoidal); Specific gravity: 3.3 to 4.3

Hardness: 5
Color: dark brown to yellowish-brown
Luster: submetallic or dull

Identified May 3, 2026More mineral →

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Physical properties

Hardness: 5.0 to 5.5; Color: dark brown to yellowish-brown; Luster: submetallic or dull; Crystal structure: orthorhombic (often massive or botryoidal); Specific gravity: 3.3 to 4.3

Formation & geological history

Formed as a secondary mineral through the weathering of other iron-rich minerals (like pyrite or magnetite) in oxygen-rich surface environments; also found as bog iron in marshy environments.

Uses & applications

Primary source of iron ore; historically used as a pigment (ochre); used in high-density aggregate for concrete and radiation shielding.

Geological facts

Goethite is named after the German polymath and mineralogist Johann Wolfgang von Goethe. It is the primary component of bog iron and is even found on the surface of Mars.

Field identification & locations

Identify in the field by its yellowish-brown streak, characteristic 'bumpy' botryoidal or slag-like texture, and lack of magnetism compared to magnetite. Found globally in weathering zones of iron deposits.