ELASTICITY OF DIOPSIDE

The thirteen single-crystal elastic moduli for diopside as determined by the acoustic technique based on Brillouin scattering are: c11=2.23, c22=1.71, c33=2.35, c44=0.74, c55=0.67, c66=0.66, c12=0.77, c13=0.81, c15=0.17, c23=0.57, c25=0.07, c35=0.43, c46=0.073. The Reuss bound of the adiabatic bulk and shear moduli calculated from these data are Ks=1.08 Mbar and G=0.651 Mbar. The room-pressure isothermal bulk modulus, KT, and the pressure derivative of the bulk modulus, K′T have also been determined on a four-circle diffractometer, from a single crystal mounted in a gasketed opposed-anvil diamond cell, giving values of KT=1.13 Mbar and K′T=4.8. The principal axes of the strain ellipsoid, calculated from the elastic moduli and observed in the static compression data, are identical, and the linear compressibilities are in reasonable agreement. The single-crystal elastic moduli can be correlated with the structural features of diopside. © 1979 Springer-Verlag.