mineral
Limonite Concretion
Hydrated Iron Oxide-Hydroxide, FeO(OH)·nH2O
Hardness varies from 4 to 5.5 on the Mohs scale, color is typically yellowish-brown, brown, or ochre, luster is earthy to submetallic, amorphous crystal structure (no distinct crystals), and no true cleavage.
Identified More mineral →
Explore Limonite Concretion in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness varies from 4 to 5.5 on the Mohs scale, color is typically yellowish-brown, brown, or ochre, luster is earthy to submetallic, amorphous crystal structure (no distinct crystals), and no true cleavage.
Formation & geological history
Formed through the oxidation and weathering of primary iron-bearing minerals or as a chemical precipitate in sedimentary environments, often found in bog ores, gossans, and residual soils.
Uses & applications
Used historically as a pigment (ochre), a minor ore of iron, and collected as odd-shaped geological curiosities.
Geological facts
Limonite is not a distinct mineral species, but rather a natural mixture of related hydrated iron oxide minerals, most commonly goethite and lepidocrocite. Unusual shapes like this specimen are formed by concentric precipitation around a nucleus.
Field identification & locations
Identified by its characteristic yellowish-brown streak, earthy texture, and lack of visible crystal faces. Commonly found worldwide wherever iron-rich rocks undergo weathering.
More like this
Other mineral specimens
Sandstone (with potential mineral staining/concretions)
Arenite (SiO2 based)
sedimentary
Soil with Mineral Detritus and Quartz Fragments
Regolith / Silicate Mineral Aggregate
sedimentary
Limonite / Goethite (Iron Ore Mineral nodule)
FeO(OH)·nH2O / FeO(OH)
mineral
Schist
Schist
Metamorphic
Septarian Pebble
Septarian nodule / Concretion
sedimentary
Potassium Feldspar (Orthoclase)
Orthoclase (KAlSi3O8)
mineral