mineral
Limonite
FeO(OH)·nH2O
AI-generated identification · may be incorrectHardness: 4 to 5.5 on the Mohs scale. Color: Brown, yellowish-brown, or ochre-yellow. Luster: Earthy, submetallic, or silky. Crystal structure: Amorphous or microcrystalline, typically forming as concretionary, mammillary, or earthy masses. Specific gravity: 2.7 to 4.3.
- Hardness
- 4 to 5
- Color
- Brown, yellowish-brown, or ochre-yellow
- Luster
- Earthy, submetallic, or silky
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Physical properties
Hardness: 4 to 5.5 on the Mohs scale. Color: Brown, yellowish-brown, or ochre-yellow. Luster: Earthy, submetallic, or silky. Crystal structure: Amorphous or microcrystalline, typically forming as concretionary, mammillary, or earthy masses. Specific gravity: 2.7 to 4.3.
Formation & geological history
Forms as an alteration product of other iron-rich minerals such as magnetite and pyrite, typically in weathering environments, bogs, and sedimentary settings.
Uses & applications
Historically used as a low-grade iron ore and as an earthy yellow pigment (ochre) for paints and ceramics.
Geological facts
Limonite is not a single distinct mineral species, but rather a mixture of related hydrated iron oxides and hydroxides, most commonly goethite and lepidocrocite.
Field identification & locations
Can be identified in the field by its characteristic yellowish-brown streak, earthy texture, and association with weathered iron deposits. Found worldwide.
