Magnesium carbonate white monoclinic crystalline or amorphous powder. Non-toxic, odorless and stable. The relative density is 2.16. It is slightly soluble in water, and its solubility in water is 0.02% (15 C). It is soluble in acid and ammonium salt solution. It is easy to decompose into magnesium oxide and carbon dioxide during calcination. When dilute acid is encountered, it decomposes and releases carbon dioxide. Usually slightly soluble in water. It is easy to react with water when heated (when hard water softens) to form magnesium hydroxide (because magnesium hydroxide is more insoluble than magnesium carbonate). Equation: MgCO3+H2O=Mg(OH)2+CO2