Jacobsite is a manganese iron oxide mineral.

It is in the spinel group and forms a solid solution series with magnetite.

[4] Typical associated minerals include hausmannite, galaxite, braunite, pyrolusite, coronadite, hematite and magnetite.

It was first described in 1869 and named for the Jakobsberg Mine, Nordmark, Filipstad, Värmland, Sweden.

[3] This article about a specific oxide mineral is a stub.