mineral
Limonite
FeO(OH)•nH2O
Hardness: 4 to 5.5 on Mohs scale; Color: Yellow-brown, dark brown, to blackish; Luster: Dull, earthy, or submetallic; Crystal structure: Amorphous, typically forms in compact, mammillary, or botryoidal masses; Cleavage: None; Specific gravity: 2.7 to 4.3
- Hardness
- 4 to 5
- Color
- Yellow-brown, dark brown, to blackish
- Luster
- Dull, earthy, or submetallic
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Physical properties
Hardness: 4 to 5.5 on Mohs scale; Color: Yellow-brown, dark brown, to blackish; Luster: Dull, earthy, or submetallic; Crystal structure: Amorphous, typically forms in compact, mammillary, or botryoidal masses; Cleavage: None; Specific gravity: 2.7 to 4.3
Formation & geological history
Forms as a secondary mineral resulting from the oxidation and weathering of various iron-bearing minerals, commonly found in gossans and sedimentary iron deposits.
Uses & applications
Used historically as an iron ore, a pigment (ochre), and in geological specimen collecting.
Geological facts
Limonite is not a true single mineral species, but rather a mixture of related hydrated iron oxides, principally goethite, lepidocrocite, and jarosite.
Field identification & locations
Easily identified by its characteristic yellowish-brown streak. Found worldwide in weathered iron-rich environments and soil profiles.
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Limonite / Goethite (Iron Ore Mineral nodule)
FeO(OH)·nH2O / FeO(OH)
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