mineral
Limonite / Brown Iron Ore
Hydrous Iron Oxide (FeO(OH)·nH2O)
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
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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.
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