Holes are drilled down through the overlying rock into the sulfur deposits. A series of concentric perforated pipes are then inserted into the drill hole. The outer pipes contain superheated steam (usually about 160 °C) which is pumped down into the deposit. Since the melting point of sulfur is so low (115.21 °C, just a little over the boiling point of water), it readily liquefies. As the sulfur becomes molten, it is removed by pumping air down the central pipe. When the molten sulfur reaches the surface, it is pumped onto wooden blocks where the sulfur again solidifies.