mineral
Limonite (Iron Ore)
FeO(OH)·nH2O
Hardness: 4 to 5.5 on Mohs scale; Color: Yellowish-brown to dark brown; Luster: Dull, earthy; Crystal Structure: Amorphous (no visible crystals); Cleavage: None; Specific Gravity: 2.7 to 4.3
- Hardness
- 4 to 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 to 5.5 on Mohs scale; Color: Yellowish-brown to dark brown; Luster: Dull, earthy; Crystal Structure: Amorphous (no visible crystals); Cleavage: None; Specific Gravity: 2.7 to 4.3
Formation & geological history
Formed as a secondary material through the oxidation or weathering of iron-rich mineral deposits (like pyrite, magnetite, or glauconite) in sedimentary environments.
Uses & applications
Historically used as a major iron ore and as a natural earth pigment (yellow ochre). Commonly used in fertilizers and for manufacturing pigments/paints today.
Geological facts
Limonite is not a true mineral in the strictest sense but a mixture of hydrated iron oxide minerals. It was the source of yellow ochre used by ancient humans in cave paintings.
Field identification & locations
Identified by its ochre-yellow streak and rusty brown appearance. Often found in bog deposits or as gossan caps over sulfide ore veins. Very common worldwide in weathered rock layers.
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