Magnesium oxide, commonly known as magnesia or magnesia oxide, is an alkaline oxide with the general properties of alkaline oxides, and belongs to the category of cementitious materials. It is a white powder (light yellow in color due to magnesium nitride), odorless, and is a typical alkaline earth metal oxide with the chemical formula MgO. The white powder has a melting point of 2852°C, a boiling point of 3600°C, and a relative density of 3.58 (at 25°C). It dissolves in acidic solutions and ammonium salt solutions but is not soluble in alcohol. Its solubility in water is 0.00062 g/100 mL (at 0°C).

0.0086 g/100 mL (30 °C). Exposed to air, it readily absorbs moisture and carbon dioxide, gradually becoming basic magnesium carbonate. Lighter grades become this more quickly than heavier ones. It combines with water under relative conditions to form magnesium hydroxide, exhibiting a slightly alkaline reaction with a pH of 10.3 in its saturated water solution. It dissolves in acids and ammonium salts but is poorly soluble in water, with its solution being alkaline. It is insoluble in ethanol. It has strong refractive properties in the visible and near-ultraviolet spectral ranges. Magnesium carbonate (MgCO3), dolomite (MgCO3·CaCO3), and seawater are the main raw materials for producing magnesium oxide. Thermal decomposition of magnesite or dolomite yields magnesium oxide. Treatment of seawater with slaked lime produces a magnesium hydroxide precipitate, which, upon calcination, yields magnesium oxide. Alternatively, magnesium chloride crystals obtained from the comprehensive utilization of seawater or brine after bromine extraction can also be used as raw materials. Adding sodium hydroxide or sodium carbonate results in the precipitation of magnesium hydroxide or basic magnesium carbonate, which is then calcined to obtain magnesium oxide. China primarily uses magnesite, dolomite, brine, or brine blocks as raw materials [1].