ATOMISTIC SIMULATION OF THE DIFFERENCES BETWEEN CALCITE AND DOLOMITE SURFACES - THE ROLE OF SURFACE SPECIATION

Abstract

Atomistic simulation methods have been used to calculate and compare the surface structures and energies of the {1014}, {0001}, {1010}, {1120} and {1011} surfaces of calcite and dolomite and to evaluate their equilibrium morphologies. The calcite {1014} and the dolomite {1010} and {1120} surfaces are the most stable crystal planes. Investigation of the segregation of Mg and Ca ions in the dolomite crystal shows a clear preference for Ca2+ ions at the surface sites and for Mg2+ ions in the bulk sites and hence growth onto dolomite results in calcium carbonate or high magnesian calcite crystals which helps explain the difficulty in crystallising dolomite vs. calcite under laboratory conditions.