What is "ferropericlase"

n. (context geology English) Any of a class of minerals, mixed oxides of magnesium and iron, that are abundant in the earth's lower mantle (second only to perovskite)

Ferropericlase or magnesiowüstite is a magnesium/ iron oxide ((Mg,Fe)O) that is interpreted to be one of the main constituents of the Earth's lower mantle together with silicate perovskite, a magnesium/iron silicate with a perovskite structure. Ferropericlase has been found as inclusions in a few natural diamonds. An unusually high iron content in one suite of diamonds has been associated with an origin from the lowermost mantle.