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