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Ferropericlase or magnesio
wüstite Wüstite ( Fe O) is a mineral form of iron(II) oxide found with meteorites and native iron. It has a grey colour with a greenish tint in reflected light. Wüstite crystallizes in the isometric-hexoctahedral crystal system in opaque to translu ...
is a
magnesium Magnesium is a chemical element with the symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 of the periodic ...
/
iron Iron () is a chemical element with symbol Fe (from la, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, right in ...
oxide An oxide () is a chemical compound that contains at least one oxygen atom and one other element in its chemical formula. "Oxide" itself is the dianion of oxygen, an O2– (molecular) ion. with oxygen in the oxidation state of −2. Most of the E ...
with the chemical formula that is interpreted to be one of the main constituents of the Earth's lower mantle together with the
silicate perovskite Silicate perovskite is either (the magnesium end-member is called bridgmanite) or (calcium silicate known as davemaoite) when arranged in a perovskite structure. Silicate perovskites are not stable at Earth's surface, and mainly exist in the lo ...
(), a magnesium/iron
silicate In chemistry, a silicate is any member of a family of polyatomic anions consisting of silicon and oxygen, usually with the general formula , where . The family includes orthosilicate (), metasilicate (), and pyrosilicate (, ). The name is a ...
with a perovskite structure. Ferropericlase has been found as inclusions in a few natural
diamonds Diamond is a solid form of the element carbon with its atoms arranged in a crystal structure called diamond cubic. Another solid form of carbon known as graphite is the chemically stable form of carbon at room temperature and pressure, ...
. An unusually high iron content in one suite of diamonds has been associated with an origin from the lowermost mantle. 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. 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.


Spin transition zone

Changes in the
spin Spin or spinning most often refers to: * Spinning (textiles), the creation of yarn or thread by twisting fibers together, traditionally by hand spinning * Spin, the rotation of an object around a central axis * Spin (propaganda), an intentionally ...
state of
electrons The electron ( or ) is a subatomic particle with a negative one elementary electric charge. Electrons belong to the first generation of the lepton particle family, and are generally thought to be elementary particles because they have n ...
in iron in mantle minerals has been studied experimentally in ferropericlase. Samples are subject to the conditions of the lower mantle in a
laser A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The word "laser" is an acronym for "light amplification by stimulated emission of radiation". The ...
-heated
diamond anvil cell A diamond anvil cell (DAC) is a high-pressure device used in geology, engineering, and materials science experiments. It enables the compression of a small (sub-millimeter-sized) piece of material to extreme pressures, typically up to around 1 ...
and the spin-state is measured using
synchrotron A synchrotron is a particular type of cyclic particle accelerator, descended from the cyclotron, in which the accelerating particle beam travels around a fixed closed-loop path. The magnetic field which bends the particle beam into its closed ...
X-ray An X-ray, or, much less commonly, X-radiation, is a penetrating form of high-energy electromagnetic radiation. Most X-rays have a wavelength ranging from 10 picometers to 10  nanometers, corresponding to frequencies in the range 30&nb ...
spectroscopy Spectroscopy is the field of study that measures and interprets the electromagnetic spectra that result from the interaction between electromagnetic radiation and matter as a function of the wavelength or frequency of the radiation. Matter ...
. Results indicate that the change from a high to low spin state in iron occurs with increasing depth over a range from 1000 km to 2200 km. The change in spin state is expected to be associated with a higher than expected increase in
density Density (volumetric mass density or specific mass) is the substance's mass per unit of volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' can also be used. Mathematicall ...
with depth along with strong variations in viscosity.


Mantle abundance

Ferropericlase 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 Perovskite (pronunciation: ) is a calcium titanium oxide mineral composed of calcium titanate (chemical formula ). Its name is also applied to the class of compounds which have the same type of crystal structure as (XIIA2+VIB4+X2−3), known a ...
; it also is the major host for iron in the lower mantle.Researchers locate mantle’s spin transition zone, leading to clues about earth’s structure
At the bottom of the transition zone of the mantle, the reaction : γ– transforms γ-olivine into a mixture of perovskite and ferropericlase and ''vice versa''. In the literature, this mineral phase of the lower mantle is also often called magnesiowüstite.Ferropericlase on Mindat.org
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See also

*
Post-perovskite Post-perovskite (pPv) is a high-pressure phase of magnesium silicate (MgSiO3). It is composed of the prime oxide constituents of the Earth's rocky mantle (MgO and SiO2), and its pressure and temperature for stability imply that it is likely to occur ...
*
Ilmenite Ilmenite is a titanium-iron oxide mineral with the idealized formula . It is a weakly magnetic black or steel-gray solid. Ilmenite is the most important ore of titanium and the main source of titanium dioxide, which is used in paints, printing ...
*
Wollastonite Wollastonite is a calcium inosilicate mineral ( Ca Si O3) that may contain small amounts of iron, magnesium, and manganese substituting for calcium. It is usually white. It forms when impure limestone or dolomite is subjected to high temperature ...
()


References

Petrology Oxide minerals {{inorganic-compound-stub