Ammonium sulphate is a salt and has the molecular formula (NH4)2SO4. The crystalline solid is colourless and odourless. Ammonium sulphate is usually produced from the reaction of ammonia in dissolved or gaseous form with 80 percent sulphuric acid. Production of ammonium sulphate by reacting ammonia, carbon dioxide and water with gypsum is also possible.
In its natural form, ammonium sulphate is known as the mineral mascagnine, which occurs only rarely.