The Earth’s Lower Mantle and Core

More than 90 percent of the Earth’s mass is composed of iron, oxygen, silicon and magnesium, distributed among a metal-rich core, a silicate-rich mantle and more highly fractionated crustal rocks (less than 1% of the total). Mantle and core compositions can be approximated quite easily provided the bulk-Earth composition is assumed to be the same as that of appropriate meteorites. Critical mineral-physics data, some of which are reviewed in this article, are then needed to develop viable compositional and thermal Earth models, thus leading to a better knowledge of the deepest rocks in the Earth.