mineral
Limonite
FeO(OH)·nH2O
Hardness: 4 to 5.5 on the Mohs scale. Color: Brown, yellowish-brown, or ochre-yellow. Luster: Earthy, submetallic, or silky. Crystal structure: Amorphous (often occurs as nodular, botryoidal, or stalactitic masses). Cleavage: None. 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 (often occurs as nodular, botryoidal, or stalactitic masses). Cleavage: None. Specific gravity: 2.7 to 4.3.
Formation & geological history
Formed through the secondary alteration and weathering of other iron-bearing minerals, often found in gossans above sulfide ore deposits or in sedimentary bog iron deposits.
Uses & applications
Historically used as an iron ore and a pigment (yellow ochre). Commonly collected as a mineral specimen.
Geological facts
Limonite is not a single, well-defined mineral, but rather a mixture of hydrated iron oxide-hydroxide minerals, principally goethite, lepidocrocite, and jarosite.
Field identification & locations
Identified primarily by its characteristic yellowish-brown streak, earthy luster, and lack of distinct crystal forms. Found worldwide wherever iron-rich rocks undergo weathering.
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Limonite / Goethite (Iron Ore Mineral nodule)
FeO(OH)·nH2O / FeO(OH)
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