UNLV geochemists have discovered a new mineral on the Earth’s surface. There’s just one catch: it shouldn’t be here.
The mineral – trapped in a diamond – has risen to the surface at least 410 miles deep in the Earth’s lower mantle, the area between the core and the planet’s crust. This is the first time that lower mantle minerals have been observed in nature, as they typically break down before reaching the Earth’s surface, unable to maintain their structure outside of a high-pressure environment. In this case, the incredible strength of the diamond preserved the mineral and made the discovery possible by scientists.
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The calcium silicate compound, CaSiOâ-perovskite, appeared as small, infinitesimal dark spots in a diamond unearthed from an African mine in the 1980s.
âFor jewelers and buyers, a diamond’s size, color, and clarity all matter and the inclusions – those black dots that annoy the jeweler – to us, it’s a gift,â the mineralogist said. ‘UNLV. Olivier Tschauner, who led the study published on November 11 in the journal Science. âI think we were very surprised. We did not expect this.
The diamond came to the surface decades ago in Botswana via the Orapa mine, the world’s largest diamond mine by area. A gemstone dealer sold the diamond in 1987 to a mineralogist at the California Institute of Technology in Pasadena, and recently Tschauner and his colleagues, including UNLV geochemist Shichun Huang, got their hands on the diamond. and applied a new suite of scientific tools to analyze its inner structure.
What they found was a new crystalline compound they named “davemaoite” after Ho-kwang “Dave” Mao, an experimental geophysicist who developed many techniques that Tschauner and his colleagues use today.
Davemaoite has been approved as a new natural mineral by the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association.
Tschauner believes davemaoite originated 410-560 miles below the Earth’s surface, and its discovery highlights one of two ways we find highly pressurized minerals in nature: deep within Earth or inside meteorites.
In 2014, the discovery of “bridgmanite” by Tschauner highlighted the latter method.
He hopes more mineral discoveries – in greater quantities – are on the horizon, which will allow scientists to model the evolution of the Earth’s mantle in more detail.
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Discovery of davemaoite, CaSiO3-perovskite, as a lower mantle mineral
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