Magnesia is an alkaline oxides, the reaction with water to form insoluble in water, magnesium hydroxide, magnesium salt with acid to generate magnesia refractories used, such as the making brick, crucibles, used as a pigment modulation paints and cosmetics, can also be used as rubber filler, insulation materials, light can be obtained calcined magnesium carbonate, magnesium hydroxide, basic magnesium carbonate can be obtained by firing heavy magnesium oxide.