Nigari has been used for hundreds years in Japan and China. Nigari is composed primarily of magnesium chloride, but may also contains other minerals found in seawater. In Japan it is sold as nigari (the term is derived from the Japanese word for "bitter"). In China it is called lushui, it is also an ingredient in baby formula milk. Only 16 ounces of nigari can make about 250 pounds of tofu, depending on firmness. Magnesium chloride is an important coagulant used in the preparation of tofu from soy milk.