Unlike potassium alum, which contains both natural and synthetic forms, Amonia Alum Crystals occur naturally as a rare mineral and is commercially manufactured by combining ammonium sulphate solution with aluminium sulphate solution. They are produced by processing bauxite ore with sulfuric acid. They consists mostly of big, colourless crystals or white powder with an astringent flavour. Ammonium alum serves almost the same functions as soda alum and potassium alum. They may be used as a leavening ingredient in baking powder, drinking water purification, etc.