sedimentary
Limonite Concretion
Goethite/Limonite concretion (FeO(OH)·nH2O)
AI-generated identification · may be incorrectHardness: 4-5.5 on the Mohs scale, Color: yellowish-brown, dark brown, or reddish-brown, Luster: earthy to submetallic, Crystal structure: amorphous or microcrystalline (pseudomorphic after pyrite or marcasite), Cleavage: none, Specific gravity: 2.7-4.3
- Hardness
- 4-5
Identified More sedimentary →
Explore Limonite Concretion in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 4-5.5 on the Mohs scale, Color: yellowish-brown, dark brown, or reddish-brown, Luster: earthy to submetallic, Crystal structure: amorphous or microcrystalline (pseudomorphic after pyrite or marcasite), Cleavage: none, Specific gravity: 2.7-4.3
Formation & geological history
Formed through the low-temperature chemical precipitation of iron oxides and hydroxides in sedimentary environments, often replacing precursor minerals like pyrite or accumulating in sandstone pores through groundwater movement.
Uses & applications
Used historically as a pigment (ochre), as an iron ore, and commonly collected as geological specimens or curiosity stones.
Geological facts
Limonite is not a true distinct mineral species, but rather a field term for a mixture of hydrated iron oxide minerals, predominantly goethite.
Field identification & locations
Easily identified by its characteristic yellowish-brown streak, concentric banding or boxwork structure, and rust-like appearance. Commonly found worldwide in weathering zones of iron-bearing rocks.
More like this
Other sedimentary specimens
Fossiliferous Sedimentary Rock
Sedimentary limestone with invertebrate fossil imprint
fossil
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Sandstone
Arenite
sedimentary
Quartz pebble
Silicon dioxide (SiO2)
sedimentary
Generic Pebble / Rock Fragment
Lithic fragment / Weathered rock
sedimentary
Shale
Shale (clastic sedimentary rock)
sedimentary