Which of the following is not the mineral of magnesium?

Magnesite:MgCO3 Magnetite:Fe3O4 Olivine:(Mg2+,Fe2+)2SiO4 Carnallite:KMgCl3.6H2O

Magnetite is a mineral whose primary component is an iron oxide that contains equal amounts of iron(II) and iron(III). Its empirical formula is Fe₃O₄, and it is often expressed as iron(II,III) oxide. In the past, it has been called ferrous–ferric oxide and triiron tetraoxide.

Magnetite is ${\mathrm{Fe}}_3{\mathrm{O}}_4$.