Magnesiowüstite

Magnesiowüstite is a mineral composing 20% of the lower mantle. It is a cubic phase of composition (Mg,Fe)O. It was assumed to exist because of the presence of a discontinuity in the propagation of seismic waves at a depth of 670 km. This discontinuity corresponds to the destabilisation of ringwoodite into magnesiowüstite and (Mg,Fe)SiO₃. The presence of this ultra high pressure mineral was confirmed by laboratory tests using diamond presses.