http://www.sciencedaily.com/releases/2011/12/111219112216.htm

New Kind of Metal in the Deep Earth: Iron Oxide Undergoes Transition Under Intense Pressures and Temperatures

ScienceDaily (Dec. 19, 2011) — The crushing pressures and intense temperatures in Earth's deep interior squeeze atoms and electrons so closely together that they interact very differently. With depth materials change. New experiments and supercomputer computations have revealed that iron oxide undergoes a new kind of transition under deep Earth conditions. Iron oxide, FeO, is a component of the second most abundant mineral at Earth's lower mantle, ferropericlase.