mineral

Limonite / Brown Iron Ore

Hydrous Iron Oxide (FeO(OH)·nH2O)

AI-generated identification · may be incorrect

Hardness: 4.0 - 5.5, Color: Yellowish-brown, ochre, to dark brown, Luster: Earthy, dull, or sub-metallic, Streak: Yellowish-brown, Structure: Amorphous or microcrystalline aggregate

Hardness: 4

Identified July 23, 2026More mineral →

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Physical properties

Hardness: 4.0 - 5.5, Color: Yellowish-brown, ochre, to dark brown, Luster: Earthy, dull, or sub-metallic, Streak: Yellowish-brown, Structure: Amorphous or microcrystalline aggregate

Formation & geological history

Forms as a secondary oxidation product of iron-rich primary minerals (such as pyrite, marcasite, and magnetite) under weathered surface or near-surface conditions.

Uses & applications

Historically used as an important iron ore and as a natural pigment (yellow ochre) in paints, cosmetics, and dyes. Used today mostly for mineral collection and localized industrial uses.

Geological facts

Limonite is not a true single mineral, but rather a mixture of hydrated iron oxide minerals including goethite, lepidocrocite, and jarosite. It gives many soils and sedimentary rocks their yellowish-brown rust color.

Field identification & locations

Recognized by its characteristic yellowish-brown streak and earthy, rusty appearance. Often found in weathered outcrops, oxidized zones of ore deposits, and streambeds.