And in the end the team of geologists in the US had to rely on a sample of the mineral in a meteorite. They describe how they came upon the bridgmanite in their paper published in Science.
Earth scientists have known about bridgmanite – high density magnesium/iron silicate – for some time.
The mineral makes up about 70% of the Earth’s lower mantle but doesn’t exist anywhere else on the planet.
And that’s been a problem. Under rules of the International Mineralogical Association, a mineral cannot be given a formal name until a sample is examined.
The meteorite-based bridgmanite was found by Oliver Tschauner of the University of Nevada, Las Vegas, and his team. The meteorite that hit Australia in 1879 had experienced intense pressure and temperatures of 2,000°C, similar to conditions deep within the Earth.
“Despite appearing for decades in numerous experimental and theoretical studies, characterisations of possible natural samples have not been sufficient to meet International Mineralogical Association criteria for naming new minerals,” Professor Tschauner wrote.
The mineral was named in honour of Percy Bridgman, a pioneer in the use of high pressure experiments to understand geological formations, who won the 1946 Nobel Prize in Physics.
Bill Condie is a science journalist based in Adelaide, Australia.
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