A new hydrate of magnesium carbonate, MgCO 3 ·6H 2 O.

During investigations of the formation of hydrated magnesium carbonates, a sample of the previously unknown magnesium carbonate hexahydrate (MgCO·6HO) was synthesized in an aqueous solution at 273.15 K. The crystal structure consists of edge-linked isolated pairs of Mg(CO)(HO) octahedra and noncoordinating water molecules, and exhibits similarities to NiCO·5.5HO (hellyerite). The recorded X-ray diffraction pattern and the Raman spectra confirmed the formation of a new phase and its transformation to magnesium carbonate trihydrate (MgCO·3HO) at room temperature.