Author name: Jay D. Bass

Seismological studies give us a high-definition 3-D picture of the Earth’s interior in terms of seismic velocity and density. Near the surface, observations of these properties can be compared with rock samples. As we go deeper into the Earth, interpretation of seismic data is more difficult. Laboratory measurements of velocities and other elastic properties of minerals are the key to understanding this seismic information, allowing us to translate it into quantities such as chemical composition, mineralogy, temperature, and preferred orientation of minerals. Here we present a description of modern techniques for measuring elastic properties at high pressures and temperatures, emphasizing those most relevant to understanding the interior of the Earth and other planets.

Very few rocks on the Earth’s surface come from below the crust. In fact, most of Earth’s interior is unsampled, at least in the sense that we do not have rock samples from it. So how do we know what is down there? Part of the answer comes from laboratory and computer experiments that try to recreate the enormous pressure–temperature conditions in the deep Earth and to measure the properties of minerals under these conditions. This is the realm of high-pressure mineral physics and chemistry. By comparing mineral properties at high pressures and temperatures with geophysical observations of seismic velocities and density at depth, we get insight into the mineralogy, composition, temperature, and deformation within Earth’s interior, from the top of the mantle to the center of the planet.