sedimentary
Limonite Sandstone
Ferruginous Sandstone (Hydrated Iron Oxide)
Hardness: 4.0-5.5 (Mohs scale), Color: Rusty brown, earthy yellow, to black, Luster: Dull/Earthy, Structure: Clastic with fine grains and iron cement, Cleavage: None
- Hardness
- 4
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Physical properties
Hardness: 4.0-5.5 (Mohs scale), Color: Rusty brown, earthy yellow, to black, Luster: Dull/Earthy, Structure: Clastic with fine grains and iron cement, Cleavage: None
Formation & geological history
Formed by the weathering of iron-rich rocks or the precipitation of iron oxides (Limonite) into porous sedimentary layers like sandstone. Common in environments with high oxidation.
Uses & applications
Historically used as a low-grade iron ore (bog iron); currently used as a landscape stone, pigment for ochre, and in teaching geology.
Geological facts
Limonite is not a true mineral but a mixture of hydrated iron oxide minerals. It was once a major source of iron for early civilizations.
Field identification & locations
Identify by its characteristic yellow-brown streak, rusty staining, and relatively high density compared to regular sandstone. Found in iron-rich sedimentary basins.
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