A review on the mineral chemistry of the non-stoichiometric iron sulphide, Fe1-xS (0 <= x <= 0.125): polymorphs, phase relations and transitions, electronic and magnetic structures

Fe1-xS (0 <= x <= 0.125), the pyrrhotite group minerals are extremely complex in their chemical and physical properties, which largely attribute to the various non-stoichiometric compositions and myriad superstructures. In this article, a review is focused on the crystal structures, phase relations and transition of the pyrrhotite group minerals.