Ferropericlase ( Mg, Fe ) O, a solid solution of periclase ( MgO ) and w�stite ( FeO ), makes up about 20 % of the volume of the lower mantle of the Earth, which makes it the second most abundant mineral phase in that region after silicate perovskite ( Mg, Fe ) SiO 3; it also is the major host for iron in the lower mantle.
