mineral

Limonite with Gossan / Iron Ore

Hydrated iron oxide-hydroxide, approximately FeO(OH)·nH2O

Hardness: 4 to 5.5 on the Mohs scale. Color ranges from yellowish-brown, dark brown, to black with characteristic yellowish-brown streak. Luster is earthy, submetallic, or silky. Crystal structure is amorphous or microcrystalline, typically forming in botryoidal, mammillary, or stalactitic masses.

Hardness: 4 to 5

Identified July 29, 2026More mineral →

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Physical properties

Formation & geological history

Formed through the secondary oxidation and weathering of primary iron-bearing sulfide minerals, often found in the weathered upper zones of ore deposits known as gossans.

Uses & applications

Historically used as a source of iron ore and as a pigment (ochre). Mainly collected as mineral specimens today.

Geological facts

Limonite is not a single mineral species, but rather a mixture of related hydrated iron oxides, most commonly goethite and lepidocrocite.

Field identification & locations

Commonly identified by its distinct yellowish-brown streak, earthy texture, and association with weathered iron deposits.

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Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

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Soil with Mineral Detritus and Quartz Fragments

Regolith / Silicate Mineral Aggregate

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Limonite / Goethite (Iron Ore Mineral nodule)

FeO(OH)·nH2O / FeO(OH)

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Schist

Metamorphic

Septarian Pebble

Septarian nodule / Concretion

sedimentary

Potassium Feldspar (Orthoclase)

Orthoclase (KAlSi3O8)

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