mineral
Limonite (Iron Ore)
Limonite (FeO(OH)·nH2O)
AI-generated identification · may be incorrectHardness: 4-5.5; Color: Yellowish-brown to dark brown; Luster: Dull, earthy; Crystal structure: Amorphous; Cleavage: None; Specific Gravity: 2.7-4.3
- Hardness
- 4-5
- Color
- Yellowish-brown to dark brown
- Luster
- Dull, earthy
Identified More mineral →
Explore Limonite (Iron Ore) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 4-5.5; Color: Yellowish-brown to dark brown; Luster: Dull, earthy; Crystal structure: Amorphous; Cleavage: None; Specific Gravity: 2.7-4.3
Formation & geological history
Formed as a secondary material through the oxidation and weathering of primary iron-bearing minerals (like pyrite or magnetite) in hydrothermal veins or sedimentary deposits.
Uses & applications
A major source of iron ore; historically used as a pigment (brown ochre) and currently sought for mineral specimens.
Geological facts
Limonite is not a single mineral but a mixture of hydrated iron oxide minerals, primarily goethite. It has been used as a pigment by humans since prehistoric times in cave paintings.
Field identification & locations
Identify by its characteristic yellowish-brown streak on a porcelain plate and its earthy, yellowish weathered appearance on outcrop surfaces. Common in gossans or 'iron hats' over sulfide deposits.
