A form of the magnesium silicate mineral MgSiO3 that is identical in composition to its more common perovskite (a group of minerals based on CaTiO3) form, but much denser. In perovskite, the atoms form a three-dimensional bonding structure, and in post-perovskite they form stacks of two-dimensional sheets. The existence of post-perovskite was discovered in 2004 when a group at the Tokyo Institute of Technology led by Kei Hirose reproduced the high temperature and pressure found in the lowermost mantle, in the D-layer close to the boundary between the mantle and outer core. Post-perovskite was the predominant mineral present and its density accounts for the previously mysterious changes in speed of seismic waves passing through this region.
Subjects: Earth Sciences and Geography.