The influence of disordered,non-equilibrium dolomites on the Mg-solubility in calcite in the system CaCO3-MgCO3

The influence of different degrees of disorder of dolomites on the solubility of MgCO₃ in calcite has been studied under isothermal and isobaric conditions. At 900° C, 4kb and 1000° C, 5 and 7kb, varied smoothly as function of the particular structural and cationic disorder of coexisting dolomite. Higher degrees of disorder of dolomite, estimated by the d _00.6/d _11.0 values and the peak height ratio I _01.5/I_00.6, lead to greater solubility of MgCO₃ in calcite. The run time for all experiments was 96 h, much longer than in previous work. The influence of disorder of dolomite on appears to be larger than that of temperature, as shown by the large range of (0.12–0.30) in calcite at 900° C 4 kb, found in this study. The state of order of dolomite seems to control the solubility limits in this system, and may explain discrepancies found in previous experimental work.