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.