mineral

Limonite (with goethite)

Hydrated Iron(III) Oxide-Hydroxide (FeO(OH)·nH2O)

Hardness: 4-5.5 (Mohs), Color: Yellowish-brown to dark brown, Luster: Dull to earthy/submetallic, Crystal Structure: Amorphous or microcrystalline, Cleavage: None

Hardness: 4-5

Identified April 7, 2026More mineral →

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Physical properties

Hardness: 4-5.5 (Mohs), Color: Yellowish-brown to dark brown, Luster: Dull to earthy/submetallic, Crystal Structure: Amorphous or microcrystalline, Cleavage: None

Formation & geological history

Formed by the chemical weathering of iron-rich minerals such as pyrite, magnetite, and hematite in oxidizing conditions, often found in oxidation zones of ore deposits.

Uses & applications

Historically used as an iron ore; currently used as a natural earth pigment (ochre) for paints and as a minor specimen for geological collections.

Geological facts

Limonite is not a true mineral but a mixtures of several hydrated iron oxide minerals. It was a primary source of iron for many early civilizations and is responsible for the yellowish-brown coloring in many soils.

Field identification & locations

Identify by its non-metallic yellowish-brown streak, earthy appearance, and lack of magnetism. Commonly found in boggy environments or as gossans atop sulfide deposits.

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