mineral
Limonite / Iron Concretion
Limonite (FeO(OH)·nH2O)
AI-generated identification · may be incorrectHardness 4-5.5, dull to earthy luster, yellowish-brown to dark brown color, amorphous/cryptocrystalline, streak yellowish-brown.
Identified More mineral →
Explore Limonite / Iron Concretion in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness 4-5.5, dull to earthy luster, yellowish-brown to dark brown color, amorphous/cryptocrystalline, streak yellowish-brown.
Formation & geological history
Forms by the oxidation and weathering of iron-rich minerals such as pyrite, siderite, or magnetite in sedimentary and hydrothermal environments.
Uses & applications
Historically mined as an iron ore; currently used as a natural pigment (yellow ochre) and by collectors.
Geological facts
Limonite is not a true single mineral, but a field term for hydrous iron oxides predominantly composed of goethite.
Field identification & locations
Recognized in the field by its characteristic mustard-yellow to brown streak and earthy habit, commonly found in gossans and sedimentary soils.
