The generation of basalts at mid-ocean ridges starts deep in the mantle and progresses as the mantle convects upward. The composition of the basalts depends on the composition of the mantle, the minerals present, the temperatures and pressures of melting, and the speed of melting and movement the melt through the mantle. Trace elements in the basalts can be used to explain much about the melting, but the explanations require that we know the ratio of the trace element in mantle minerals to the amount in the melted mantle. These ratios (distributions) are determined in laboratory experiments on mantle minerals at high temperature and pressure. This project is to extend the range of pressures at which we know the distributions of several elements.