Magnesite is the general name of minerals with high magnesium content. For example, brucite is a rare high magnesium mineral, also known as "magnesium hydroxide". Its chemical composition is Mg (OH) 2, the theoretical content of MgO is 69%, and the metallic magnesium is 41.6%. It is a high-quality magnesium ore. Periclase (mainly composed of MgO) made from brucite after calcination is a high-grade refractory.