Ferrous sulfate, also called as iron (II) sulfate, is a salt with the formula FeSO4·xH2O. Ferrous sulfate exists in hydrous and anhydrous form. Hydrous and anhydrous ferrous sulfate mainly exist in the form of heptahydrate. Ferrous sulfate is commonly found as a hydrated salt. The hydrous forms of ferrous sulfate are monohydrate, tetrahydrate, pentahydrate, and heptahydrate. The most commonly used hydrous ferrous sulfate is monohydrate and heptahydrate.