Scientists have discovered the first instance of a never-before-seen mineral inside a diamond pulled from deep down the Earth's surface. The material was supposed to be impossible to locate on Earth's surface, according to researchers.
Davemaoite is the first example of a high-pressure calcium silicate perovskite (CaSiO3) discovered on Earth, named after eminent geophysicist Ho-kwang (Dave) Mao.
Davemaoite is a crystalline mineral found in the Earth's mantle, the mainly solid layer between the outer core and the crust. Another form of CaSiO3, known as wollastonite, is widely found around the world, but wollastonite has a crystalline structure that forms only under high pressure and high temperatures in Earth's mantle.
For a very long period of time, davemaoite was thought to be a common and significant geochemical mineral in the Earth's mantle. However, since it breaks down into other minerals as it travels closer to the surface and pressure falls, scientists have never uncovered direct proof of its presence.
However, a davemaoite sample was found in a Botswana diamond that formed in the mantle 410 miles (660 kilometers) below Earth's surface. As a result, davemaoite has been certified as a new mineral by the International Mineralogical Association.
The finding of davemaoite was unexpected, lead author and mineralogist Oliver Tschauner of the University of Nevada, Las Vegas, told Live Science.
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How Scientists Uncovered the Davemaoite Sample
Tschauner and his colleagues discovered the davemaoite sample using synchrotron X-ray diffraction, a method that precisely concentrates a high-energy beam of X-rays on specific areas inside the diamond.
Scientists can figure out it contents by analyzing the angle and magnitude of the returning light, according to Tschauner. He stated that since the sample of davemaoite inside the diamond was just a few micrometers in size, less-powerful sampling methods would have missed it.
Davemaoite is thought to have a geochemical function in the Earth's mantle. Other trace elements such as uranium and thorium, which produce heat via radioactive decay, are thought to be present in the material, according to scientists.
As a result, davemaoite may contribute in the generation of significant heat in the mantle, according to Tschauner.
Hope to Discover Other High-Pressure Phases
Another hypothetical high-pressure mineral from the mantle, known as bridgmanite, was reported in a 2014 paper published in the journal Science. The bridgmanite sample, on the other hand, did not come from the mantle, but rather from inside a meteorite.
The finding of davemaoite demonstrates that diamonds may develop deeper in the mantle than previously believed, and it implies that the mantle may be the greatest area to seek for novel minerals, according to Tschauner.
In a related Science article, Yingwei Fe, a geophysicist at the Carnegie Institution for Science in Washington, D.C., who was not part of those who carried out the research, said that the work by Tschauner et al. inspires optimism in the finding of additional challenging high-pressure phases in nature.
According to Yingwei Fe, such direct sampling of the inaccessible lower mantle would fill the gap in the understanding of the chemical composition of the planet's whole mantle.
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