Ferrous sulfate is an important source of divalent iron used across agriculture, animal nutrition, water treatment and various industrial processes. Commercial and naturally occurring ferrous sulfate exists in several hydration states. Among them, ferrous sulfate heptahydrate (FeSO₄·7H₂O) and ferrous sulfate monohydrate (FeSO₄·H₂O) are the most commercially relevant, while ferrous sulfate tetrahydrate (FeSO₄·4H₂O) is mainly encountered as an intermediate hydration phase. Alth