：It appears light bluish green monoclinic crystalline form or granular. No smell, saline and bitter. Prone to efflorescence in dry air, and oxidizing in moist air, generating yellow brown ferrous sulfate on surface. It is mainly used to produce ferrous oxide dye series, also used for wastewater treatment, water purification and production of poly ferrous sulfate, iron catalyst, mordant and as additive for compound fertilizers.