sedimentary
Limonite Ironstone
Goethite-Limonite concretion / Iron oxide
Hardness: 4 to 5.5 on the Mohs scale; Color: Yellow-brown, reddish-brown, to dark brown; Luster: Earthy to submetallic; Crystal structure: Amorphous to microcrystalline; Specific gravity: 2.7 to 4.3
- Hardness
- 4 to 5
- Color
- Yellow-brown, reddish-brown, to dark brown
- Luster
- Earthy to submetallic
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Physical properties
Hardness: 4 to 5.5 on the Mohs scale; Color: Yellow-brown, reddish-brown, to dark brown; Luster: Earthy to submetallic; Crystal structure: Amorphous to microcrystalline; Specific gravity: 2.7 to 4.3
Formation & geological history
Formed through the weathering and oxidation of iron-bearing minerals or through chemical/biochemical precipitation in sedimentary environments, often found as nodules, crusts, or concretions.
Uses & applications
Used historically as an iron ore, a pigment (ochre), and as a specimen for mineral collectors.
Geological facts
Limonite is not a distinct mineral species, but rather a natural mixture of hydrated iron oxide minerals, predominantly goethite, lepidocrocite, and quartz clays.
Field identification & locations
Can be identified in the field by its characteristic yellowish-brown streak and earthy appearance. Commonly found worldwide in weathering zones of iron deposits.
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