Bittern, better known as it's chemical name Magnesium chloride, is the name for the chemical compounds with the formulas MgCl2 and its various hydrates MgCl2(H2O)x. These salts are typical ionic halides, being highly soluble in water. The hydrated magnesium chloride can be extracted from brine or sea water, however, it is usually mined (through solution mining) as the natural mineral Bischofite out of ancient seabeds. Magnesium chloride is an important coagulant used in the preparation of tofu from soy milk. It is also a common an anti-icer and to control dust and erosion on unimproved roads as well as dusty job sites such as quarries.