Jacobsite

A species of Minerals

Jacobsite is a manganese iron oxide mineral. It is in the spinel group and forms a solid solution series with magnetite. The chemical formula is MnFe2O4 or with oxidation states and substitutions: (Mn,Fe,Mg)(Fe,Mn)2O4. It occurs as a primary phase or as alteration of other manganese minerals during metamorphism of manganese deposits. Typical associated minerals include hausmannite, galaxite, braunite, pyrolusite, coronadite, hematite and magnetite. It is a ferrimagnetic substance, which is weakly attracted by a magnet. It was first described in 1869 and named for the Jakobsberg Mine, Nordmark, Filipstad, Värmland, Sweden.

Hardness:

5.5 - 6.5

Density:

5.03 g/cm³