mineral
Limonite/Goethite (Iron Ore)
Hydrous ferric oxides (FeO(OH)·nH2O)
Hardness: 4.0-5.5 on Mohs scale; Color: Yellowish-brown to dark brown; Luster: Dull to earthy; Crystal structure: Amorphous or microcrystalline; Cleavage: None; Specific Gravity: 2.7 to 4.3
- Hardness
- 4
- Color
- Yellowish-brown to dark brown
- Luster
- Dull to earthy
Identified More mineral →
Explore Limonite/Goethite (Iron Ore) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 4.0-5.5 on Mohs scale; Color: Yellowish-brown to dark brown; Luster: Dull to earthy; Crystal structure: Amorphous or microcrystalline; Cleavage: None; Specific Gravity: 2.7 to 4.3
Formation & geological history
Secondary mineral formed by the oxidation and weathering of primary iron-bearing minerals like pyrite, magnetite, and hematite in sedimentary or hydrothermal environments.
Uses & applications
Historically used as a major source of iron ore and as a natural pigment (brown ochre) for paints and cosmetics.
Geological facts
Limonite is not a true mineral but a mixture of hydrated iron oxide minerals. It was often the source of iron for early bog iron smelting operations.
Field identification & locations
Identify by its characteristic yellowish-brown streak (when rubbed on unglazed porcelain) and lack of magnetism compared to magnetite. Commonly found in gossans (iron-caps) above ore deposits.
More like this
Other mineral specimens
Sandstone (with potential mineral staining/concretions)
Arenite (SiO2 based)
sedimentary
Schist
Schist
Metamorphic
Epidote
Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)
metamorphic
Gypsum (variety Selenite or Alabaster)
Calcium sulfate dihydrate (CaSO4·2H2O)
Mineral
Nephrite Jade
Nephrite
Mineral/Rock
Banded Gneiss (River Rock/Pebble)
Gneiss (specifically a banded variety often found as a river rock)
Metamorphic Rock