[1] Discrete ultralow-velocity zones in the deepest parts of the mantle, near the Earth's core, are thought to be blobs of ferropericlase, as seismic waves are significantly slowed as they pass through them, and ferropericlase is known to have this effect at the high pressures and temperatures found deep within the Earth's mantle.
[2] In May 2018, ferropericlase was shown to be anisotropic in specific ways in the high pressures of the lower mantle, and these anisotropies may help seismologists and geologists to confirm whether those ultra-low velocity zones are indeed ferropericlase, by passing seismic waves through them from various different directions and observing the exact amount of change in the velocity of those waves.
[3] Changes in the spin state of electrons in iron in mantle minerals has been studied experimentally in ferropericlase.
Samples are subject to the conditions of the lower mantle in a laser-heated diamond anvil cell and the spin-state is measured using synchrotron X-ray spectroscopy.
[6] At the bottom of the transition zone of the mantle, the reaction transforms γ-olivine into a mixture of perovskite and ferropericlase and vice versa.