Trevorite is a rare nickel iron oxide mineral belonging to the spinel group. It has the chemical formula NiFe3+2O4. It is a black mineral with the typical spinel properties of crystallising in the cubic system, black streaked, infusible and insoluble in most acids. There is at least partial solid solution between trevorite and magnetite, with many magnetites from ultramafic rocks containing at least trace amounts of Ni. Fe2+ and Mg2+ may substitute for Ni in trevorite.