Iron(II) sulfate (Br.E. iron(II) sulphate) or ferrous sulfate is the chemical compound with the formula FeSO₄. It is used medically to treat iron deficiency, and also for industrial applications. Known since ancient times as copperas and as green vitriol, the blue-green heptahydrate is the most common form of this material. All iron sulfates dissolve in water to give the same aquo complex (Fe(H₂O)₆)²⁺, which has octahedral molecular geometry and is paramagnetic.