Diadochite

Diadochite is a phospho-sulfate mineral. It is a secondary mineral formed by the weathering and hydration of other minerals. Its formula is Fe₂(PO₄)(SO₄)OH·5H₂O. Well crystallized forms are referred to as destinezite, which has been given official recognition by the International Mineralogical Association with diadochite being the poorly formed to amorphous variety.