Green vitriol is also known as ferrous sulfate, iron (II) sulfate, copperas, or melanterite. Ferrous sulfate is a greenish-blue crystalline solid that is soluble in water and alcohol. It is commonly used as a soil amendment, in the treatment of iron deficiency anemia, and as a reducing agent in chemical manufacturing. The term "copperas" refers to ferrous sulfate that has been produced from the decomposition of sulfuric acid with iron and copper ores. Melanterite is a mineral form of ferrous sulfate that occurs naturally in sulfide deposits and in acid sulfate soils. While "green vitriol" is the historic term for ferrous sulfate, these alternative names are more widely used in modern language.