mineral
Limonite (Iron Ore)
Limonite (FeO(OH)·nH2O)
Hardness: 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.
More like this
Other mineral specimens
Sandstone (with potential mineral staining/concretions)
Arenite (SiO2 based)
sedimentary
Sandstone with Mineral Veining or Crust
Sedimentary Sandstone (mostly SiO2 with Fe2O3 tinting)
sedimentary
Schist
Schist
Metamorphic
Potassium Feldspar (Orthoclase)
Orthoclase (KAlSi3O8)
mineral
Gypsum (variety Selenite or Alabaster)
Calcium sulfate dihydrate (CaSO4·2H2O)
Mineral
Epidote
Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)
metamorphic