Fig. 2.
(A) Pressure dependence of volume per formula unit of CaMg0.6Fe0.4(CO3)2 dolomite (black), dolomite-II (blue) and dolomite-III (red) as investigated by single crystal X-ray diffraction studies at ambient temperature. For comparison, the volume of a isochemical mixture of aragonite and the (Mg,Fe)CO3 phase in the magnesite-siderite solid-solution is also reported (green). Data are taken (23,35,36) (B) Evolution of C─O distances (for selected carbon atom) in dolomite-III structure as function of pressure, and linear extrapolation over an extended pressure range.