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magnesium carbonate[mag′nē·zē·əm ′kär·bə‚nāt]
MgCO3, a salt; colorless crystals. Density, 3.037 g/cm3. The decomposition of magnesium carbonate into MgO and CO2 is partial at 500°C and complete at 650°C Its solubility in water is low (22 mg/l at 25°C) and decreases with increasing temperature. Upon saturation of an
aqueous suspension of MgCO3 with CO2, the MgCO3 dissolves because of the formation of the hydrocarbonate Mg(HCO3)2. Basic magnesium carbonates are extracted from aqueous solutions in the absence of excess CO2. Magnesium carbonate interacts with metal carbonates to form double salts, an example of which is the natural mineral dolomite, MgCO3,CaCO3. Magnesium carbonate is widespread in nature in the form of the mineral magnesite. Basic magnesium carbonate, 3MgCO3,Mg(OH)2,3H2O, is used as a filler in rubber mixes, in the manufacture of thermal-insulation materials, and in medicine (as a tooth-powder ingredient and internally to counteract increased acidity).