Zinc Sulfate (also spelled zinc sulphate) is a very water soluble, clear, crystalline compound prepared by heating zinc sulphide ore in air and dissolving out and recrystallizing the sulphate. It is commonly used as the heptahydrate form; it occurs naturally as the mineral goslarite, and can be prepared by reacting zinc with sulfuric acid. The crystalline sulfate is known commonly as white vitriol. It loses water at 30°C to give the hexahydrate and more water is lost at 70°C to form the monohydrate. The anhydrous salt forms at 280°C and this decomposes above 500°C. It is used in agriculture as a weed killer and to give protection against pests; It is used to supply zinc in animal feeds and fertilizers; It is also an important constituent of the precipitating bath in the manufacture of viscose rayon and in electrolyte for zinc plating; It functions as a mordant in dyeing; as a preservative for skins and leather; and as an astringent and emitic in medicine.