mineral
Limonite (Iron Ore)
FeO(OH)·nH2O
AI-generated identification · may be incorrectHardness: 4-5.5 (Mohs scale); Color: Yellow-brown to black; Luster: Dull, earthy to submetallic; Crystal Structure: Amorphous or microcrystalline; Cleavage: None; Specific Gravity: 2.7-4.3
- Hardness
- 4-5
- Color
- Yellow-brown to black
- Luster
- Dull, earthy to submetallic
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Physical properties
Hardness: 4-5.5 (Mohs scale); Color: Yellow-brown to black; Luster: Dull, earthy to submetallic; Crystal Structure: Amorphous or microcrystalline; Cleavage: None; Specific Gravity: 2.7-4.3
Formation & geological history
Formed by the oxidation of iron-rich mineral deposits (like pyrite/magnetite) or through the precipitation in swampy environments (bog iron). Common in weathering zones of ore bodies.
Uses & applications
Historically used as a major source of iron ore; currently used as a pigment in paints (yellow ochre) and for mineral specimens.
Geological facts
Limonite is not a true mineral but a mixture of hydrated iron oxide minerals. It was once the primary source of iron for ancient civilizations and is the source of the yellow color in most desert sands.
Field identification & locations
Identified by its signature yellow-brown streak, earthy habit, and association with other oxidized iron minerals. Common in sedimentary layers and weathered gossans.
