HIGH-PRESSURE BEHAVIOUR AND EQUATION OF STATE OF CALCITE, CACO3

Abstract

The high-pressure response of the cell parameters of calcite, CaCO3, has been investigated by single crystal X-ray diffraction. The unit cell parameters have been refined from 0 to 1.435 GPa, and the linear and volume compressibilities have been measured as βa=2.62(2) × 10-3 GPa-1, βc=7.94(7) × 10-3 GPa-1, βv=13.12 × 10-3 GPa-1. The bulk modulus has been obtained from a fit to the Birch-Murnaghan equation of state, giving K0=73.46 ± 0.27 GPa and V0=367.789 ± 0.004 A3 with K'=4. Combined with earlier data for magnesite, ankerite and dolomite, these data suggest that K0V0 is a constant for the Ca-Mg rhombohedral carbonates.