This work will focus on the measurements of elastic constants of geophysically important minerals at high temperatures (above 1500 K, or in some cases up to the melting point), and especially those of iron bearing minerals such as fayalite, olivine, and pyroxene. This will require setting up a controlled flow oxygen pressure environment around the experiment, similar to that used in defect studies, and will require the use of new specialized talent skilled in oxygen fugacity control. The anharmonic properties and empirical relationships between anharmonic properties at high temperature for the three minerals will be measured. These relationships are very helpful in giving constraints on mantle convection theories and seismic tomography.