Magnesite is a kind of magnesium carbonate mineral, which is the main source of magnesium. Magnesium-containing solutions can transform calcite into magnesite when they act on calcite, so magnesite belongs to calcite group. Magnesium-rich rocks also change into magnesite. Magnesite often contains iron, which is the result of replacement of magnesium by iron or manganese. Magnesite is white or grayish-white with a glassy luster, and iron-bearing magnesite appears yellow to brown. If a crystal appears, it is granular, but if it does not appear, it is massive. Magnesite can also be used as refractory and as a compound for the production of magnesium in addition to the extraction of magnesium.