Magnesium carbonate, MgC03, is a light, bulky white powder, very slightly soluble in water,loses CO2 even on gentle heating. It is used extensively in the manufacture of food products, pharmaceuticals, cosmetics, and magnesium salts.
Magnesium carbonate occurs in nature in several minerals as hydrated, basic and double salts, as shown above. The two principal minerals are magnesite, MgCO3 and dolomite, a double salt, CaCO3•MgCO3. Both minerals are used as source materials in the production of magnesium metal. Also, they are calcined to produce basic refractory bricks. Other applications of magnesium carbonate are in flooring, fireproofing and fire-extinguishing compositions; as a filler material and smoke suppressant in plastics; as a reinforcing agent in neoprene rubber; as a drying agent and for color retention in foods; in cosmetics; in dusting powder; and in toothpaste. The high purity magnesium carbonate is used as an antacid in medicine; and as an additive to table salt. Another important application of magnesium carbonate is as a starting material in producing a number of magnesium compounds.