The high-pressure, single-crystal elasticity of pyrope, grossular, and andradite

Brillouin spectroscopy was used at pressure to obtain elastic stiffness constants of pyrope, grossular and andradite, natural garnets. Acoustic velocities were measured at pressures to 10 GPa in a diamond-anvil cell. Cauchy relations altered with pressure for grossular and andradite, indicating that they are constant and not suitable for extrapolation to high pressures.