Crystal Structures of Minerals in the Lower Mantle

The crystal structures of lower mantle minerals are vital components for interpreting geophysical observations of Earth's deep interior and in understanding the history and composition of this complex and remote region. While bridgmanite, ferropericlase, and Calcium silicate (CaSiO3) perovskite are expected to make up the bulk of the mineralogy in most of the lower mantle, other phases such as Silicon dioxide (SiO2) polymorphs or hydrous silicates and oxides may play an important subsidiary role or may be regionally important. This chapter describes the crystal structure of the key minerals expected to be found in the deep mantle and discusses some examples of the relationship between structure and chemical and physical properties of these phases. There is considerable interest in the potential role of hydrogen in deep-mantle crystal structures, as the presence of hydrogen can strongly affect physical and chemical properties such as melting, viscosity, phase transitions, and seismic velocities.