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A phase transition in (Mg, Fe) SiO3 (magnesium silicate-perovskite) for pressure-temperature conditions near the base of Earth's mantle, first reported in May 2004, is stimulating strong multidisciplinary excitement and interactions. Experimentally and theoretically determined characteristics of this phase transition indicate that it may hold the key to understanding enigmatic seismological structures in the D” region of the lowermost mantle, with important implications for heat transport, thermal instabilities, and chemical properties of the lower mantle.

All minerals undergo phase transitions with increasing depth into the Earth, reorganizing their crystal structures into denser-packed forms stable over a finite range of pressures and temperatures. The changes in material properties across such transitions often give rise to detectable contrasts in seismic velocities and density.