ATOMISTIC SIMULATION OF THE DIFFERENCES BETWEEN CALCITE AND DOLOMITE SURFACES

Atomistic simulation methods have been used to calculate and compare t he surface structures and energies of the {<10(1)over bar 4>}, {0001}, {<10(2)over bar 0>}, {<10(1)over bar 0>} and {<11(2)over bar 0>} surf aces of calcite and dolomite and to evaluate their equilibrium morphol ogies. The calcite {<10(1)over bar 4>} and the dolomite {<1(01)over ba r 0>} and {<11(2)over bar 0>} surfaces are the most stable crystal pla nes. Investigation of the segregation of Mg and Ca ions in the dolomit e 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 res ults in calcium carbonate or high magnesian calcite crystals which hel ps explain the difficulty in crystallising dolomite vs. calcite under laboratory conditions. Copyright (C) 1998 Elsevier Science Ltd.