Mantle diamonds contain mysterious minerals that have never been seen before

Sina science and technology news Beijing time on November 16, according to foreign media reports, scientists found an unprecedented mineral in a diamond excavated from deep underground for the first time. Previously, they thought that the mineral could not be found on the earth.

This mineral is named after the famous Chinese geophysicist Mao Heguang – “davemaoite”. It is the first high-pressure silicate perovskite (CaSiO3) found on the earth. Another form of CaSiO3 is called wollastonite, which is distributed all over the world. However, the crystal structure of davemaoite can only be formed under the conditions of high pressure and high temperature in the mantle, The mantle is the main solid layer between the earth’s core and the earth’s crust.

Wollastonite was once considered as a mineral with rich reserves and important geochemical significance in the mantle, but scientists have not found any direct evidence to prove its existence for many years, because when it moves towards the surface, the pressure decreases and it will decompose into other minerals. However, at present, when scientists analyze a diamond from Botswana, the analysis shows that it is formed in the mantle layer 660 kilometers underground. The diamond contains a complete sample of hair calcium silicate. Therefore, the international mineral association has confirmed that it is a new type of mineral.

Oliver Jonah, the first author of the Research Report and a mineralogist at the University of Nevada in the United States, said: “the discovery of wollastonite is surprising!” it is reported that Jonah and his colleagues found that the diamond contains wollastonite structure by using a technology called synchronous X-ray diffraction. X-ray diffraction can focus high-energy X-rays at a certain point in the diamond with microscopic accuracy. By measuring the angle and intensity of the return light, researchers can crack the composition of the diamond, “Jonah said.” the diameter of the wool calcium silica sample in Botswana diamond is only 6 microns (one million one meter), so ordinary mineral sampling technology may not get a new development.

Wollastonite is considered to play an important geochemical role in the mantle. Scientists speculate that the mineral may also contain other trace elements, including uranium and thorium, which release heat through radioactive decay. Therefore, Jonah pointed out that wollastonite may help to generate a lot of heat in the mantle.

A study published in Science in 2014 pointed out that researchers described another high-pressure mineral theoretically from the mantle, called “bridgmanite”, but the mineral did not come from the mantle, but from the interior of the meteorite. Jonah said that the discovery of wollastonite shows that diamonds can form deep in the mantle, deeper than previously expected, which means that the best mining sites for more new minerals can be found in the mantle.

In an article published in the journal Science, geophysicist Yingwei Fe of Carnegie Institute said that the wollastonite discovered by Jonah et al. Brings hope to the exploration of other high-pressure mining sites in nature. This inaccessible deep mantle sample collection will fill our knowledge gap of the chemical composition of the whole mantle. At present, the latest research report is published in the journal Science on November 11. (Ye Qingcheng)



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