Earth has one more mineral: diamond davemaoite found in the Earth's mantle


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One diamond found in the bowels of Botswana contains invaluable information for the scientific world. Inside it was in fact found a mineral hitherto unknown , which is named davemaoite in honor of the Chinese-American geologist Ho-kwang Dave Mao . It is in particular calcium silicate perovskite (CaSiO3), already known theoretically but for the first time ever found on Earth in a natural sample , hidden inside a diamond.

Davemaoite has a crystalline structure capable of forming only at very high pressure and at high temperatures inside the earth’s mantle, or the layer between the crust and the core (which has recently been discussed: a study has doubt its composition). The discovery is important as the theory is confirmed that this mineral is not only abundant in the Earth’s mantle, but also essential for the dynamics of the Earth . Until now there had been no proof: its discovery was a more unique than rare event, since with its displacement towards the surface of the planet and with the consequent reduction of pressure, perovskite tends to break down into other minerals . The fact that she got trapped inside a diamond formed at 660 km of depth has ensured that its composition remained completely intact.

HOW IT WAS IDENTIFIED

The Synchroton X-ray Diffraction (XRD ), through which the angle and intensity of the return light generated by X-rays sent to precise points inside the diamond were measured. This measurement allowed the researchers to reconstruct the internal composition of the diamond and to identify the davemaoite, present in very small quantities (micrometers) but sufficient to give answers and confirmations to the scientific world.

WHY IT’S SO IMPORTANT

It is not so much the davemaoite that is important (it is however the first time ever that its existence has been demonstrated), as the role it has at interior of the Earth’s lower mantle : the chemical-structural analysis has shown that the mineral is able to host uranium, thorium and potassium , elements that are not only “ incompatible in the upper mantle “, but which, due to their intrinsic properties,” affect the generation of heat in the lower mantle of the Earth “.

Our observations indicate that davemaoite also hosts potassium in its structure in addition to uranium and thorium. Hence, regional and global abundances of davemaoite affect the heat balance of the deep mantle, where the mineral is thermodynamically stable.

In addition, with the discovery described in the study – published in Science – it was discovered how diamonds can form at greater depths than those up to now hypothesize.


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