Ammonium sulfate
Finely divided gypsum is added to an ammonium carbonate solution. Calcium carbonate precipitates as a solid, leaving ammonium sulfate in the solution. (NH 4) 2 CO 3 + CaSO 4 → (NH 4) 2 SO 4 + CaCO 3. Ammonium sulfate occurs naturally as the rare mineral mascagnite in volcanic fumaroles and due to coal fires on some dumps. Properties