Recent progress in studies of the elastic properties of earth materials

Technological advances now allow the elastic moduli and acoustic wave velocities of minerals to be measured or calculated under extreme conditions of pressure and temperature (P and T) that closely mimic the P-T conditions throughout much of Earth's interior. In this special issue, the papers on the elasticity of Earth materials report new results that provide excellent examples of these advances. Here we briefly discuss the scientific context for the elasticity papers in this special issue, and some of the future challenges that are critical for advancing our understanding of the compositional state of the deep Earth through studies of the elastic properties of materials.