Jacobsite
![](/Images/godic/202501/21/Jakobsit_-_Jakobsberg,_Schweden0930.jpg")
![Jacobsite, N'Chwaning Mines, Kuruman, Kalahari manganese fields, Northern Cape Province, South Africa. Size 3.8 x 3.5 x 3.2 cm](/Images/godic/202501/21/Jacobsite-d05-134a0931.jpg")
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.