Magnesite is a magnesium carbonate mineral with a chemical composition of MgCO3. It is named after the presence of magnesium in its composition. Magnesite forms during the alteration of magnesium-rich rocks or carbonate rocks by metamorphism or chemical weathering. Magnesite is used to produce magnesium oxide (MgO), which serves as a refractory material for the steel industry and as a raw material for the chemical industry. Magnesite is used to produce magnesium oxide (MgO), which serves as a refractory material for the steel industry and as a raw material for the chemical industry. Small amounts of magnesite are also used as a gem and lapidary material. Magnetite Data Molecular Weight = 84.31 gm Magnesium 28.83 % Mg 47.80 % MgO Carbon 14.25 % C 52.20 % CO2 Oxygen 56.93 % O ______ ______ 100.00 % 100.00 % = TOTAL OXIDE