Limonite is a hydrated iron oxide. It is formed by the dissolution of other minerals rich in iron. The term limonite indicates pseudomorphic masses of iron oxides and hydroxides without visible crystals. It is not a separate mineralogical species but a mixture of minerals and amorphous materials among which goethite and hematite prevail. It rarely has a crystalline form that generally reflects that of the iron ore from which it was formed, such as pyrite and siderite crystals. More commonly it is found in the form of concretions, stalactite masses, clusters-kidney-shaped and earthy. The earthy masses of limonite have colors ranging from light brown to ocher brown and are used as dyes. It is one of the minerals containing the most iron (Fe) and, for this reason, it is widely used by the metallurgical industry. It is often referred to as "swamp iron" since its formation is typical of swampy environments. In Italy, limonite is found in abundance in Sardinia and on the Island of Elba.
Dimensions
Size (cm): 5-8
Weight (g): 70-200
Property
Chemical Formula: 2Fe2O3 · 3H2O
Mohs scale: 4-5.5
Relative density: 2.7 - 4.3
Crystalline System: Variable
