High-pressure behaviour and equation of state of calcite, CaCO3

The high-pressure response of the cell parameters of calcite, CaCO3, has be en investigated by single crystal X-ray diffraction. The unit cell paramete rs have been refined from 0 to 1.435 GPa, and the linear and volume compres sibilities have been measured as beta(a) = 2.62(2) x 10(-3) GPa(-1), beta(c ) = 7.94(7) x 10(-3) GPa(-1), beta(v) = 13.12 x 10(-3) GPa(-1). The bulk mo dulus has been obtained from a fit to the Birch-Murnaghan equation of state , giving K-0 = 73.46 +/- 0.27 GPa and V-0 = 367.789 +/- 0.004 Angstrom(3) w ith K' = 4. Combined with earlier data for magnesite, ankerite and dolomite , these data suggest that K0V0 is a constant for the Ca-Mg rhombohedral car bonates.