sedimentary
Limonite/Hematite Ironstone
Goethite-rich Ironstone (FeO(OH) · nH2O)
Hardness: 4-5.5 | Color: Yellowish-brown to rust-orange | Luster: Dull, earthy | Structure: Amorphous or massive | Cleavage: None | Specific Gravity: 2.7-4.3
- Hardness
- 4-5
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Physical properties
Hardness: 4-5.5 | Color: Yellowish-brown to rust-orange | Luster: Dull, earthy | Structure: Amorphous or massive | Cleavage: None | Specific Gravity: 2.7-4.3
Formation & geological history
Formed through the oxidation and hydration of iron-rich minerals in sedimentary environments or by the weathering of hydrothermal ore deposits. It often forms as a secondary mineral in bog iron or as a pseudomorph.
Uses & applications
Historically used as a minor iron ore and a source of natural pigment (yellow ochre). Commonly collected as garden stones or for geological study.
Geological facts
The term 'Limonite' is actually a catch-all field name for a variety of hydrated iron oxides. It was a primary source of iron for thousands of years until modern mining of major hematite deposits began.
Field identification & locations
Identify by its characteristic 'rust' color and yellowish-brown streak on a ceramic plate. It is relatively heavy for its size and often appears as rounded concretions or irregular masses. Found worldwide in weathered zones.
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