mineral
Limonite (Ironstone)
FeO(OH)·nH2O (Hydrous ferric oxides)
AI-generated identification · may be incorrectHardness: 4-5.5 (Mohs scale); 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 (Ironstone) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 4-5.5 (Mohs scale); Color: Yellowish-brown to dark brown; Luster: Dull/Earthy; Crystal Structure: Amorphous; Cleavage: None; Specific Gravity: 2.7-4.3
Formation & geological history
Formed by the oxidation and hydration of iron-rich mineral ores (like pyrite or magnetite) through weathering. Common in soil horizons and Bog Iron deposits.
Uses & applications
Primary source of yellow ochre pigment for paints; historical source of iron ore for smelting; used in water filtration systems.
Geological facts
Limonite is not a true mineral but a mixture of hydrated iron oxides. It was used by prehistoric humans as one of the first cave-painting pigments.
Field identification & locations
Identify by its characteristic yellowish-brown streak on a porcelain plate and its earthy, rusted appearance. Often found in swampy areas or gossans above ore bodies.
More like this
Other mineral specimens
Gneiss or Schist
Gneiss or Mica Schist with Garnet
Metamorphic
Sandstone (with potential mineral staining/concretions)
Arenite (SiO2 based)
sedimentary
Tumbled granite
Granite, a coarse-grained felsic intrusive igneous rock
igneous
Epidote
Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)
metamorphic
Pegmatite with Tourmaline and Quartz
Igneous Pegmatite
igneous
Granite
Granite (Phaneritic intrusive igneous rock)
igneous