FeSO4

Ferrous sulfate, with the chemical formula FeSO4, is an inorganic compound used as a source of iron. The most common commercial form is the heptahydrate FeSO4·7H2O, known as green vitriol; anhydrous FeSO4 is less common. In aqueous solution, ferrous sulfate provides Fe2+ ions, but the solution can rapidly oxidize to Fe3+ when exposed to air, often changing color.

Ferrous sulfate occurs naturally as the mineral melanterite (the hydrated form FeSO4·7H2O). Industrially, it is produced by treating iron with sulfuric acid or by processing minerals containing iron and sulfuric compounds; the heptahydrate crystallizes from water as the product is cooled or concentrated.

Uses of ferrous sulfate include medical and agricultural applications. It is widely used as an oral iron supplement to treat and prevent iron-deficiency anemia. In horticulture, it serves as a source of iron to correct chlorosis in plants, particularly in acidic or nutrient-poor soils. In chemical laboratories, ferrous sulfate acts as a reducing agent for various organic and inorganic reactions and is used in some metallurgical and pigment applications.

Safety and handling considerations are important. Ferrous sulfate can irritate the skin, eyes, and mucous membranes, and ingestion in large amounts is hazardous. It can interact with certain medications, such as tetracycline and quinolone antibiotics, reducing their absorption. It should be stored in a dry place away from oxidizing agents to minimize premature oxidation.