A space rock has helped scientists characterize, and finally name, the planet’s most common mineral. The newly christened “bridgmanite,” named after physicist Percy Bridgman, is a high-density form of magnesium iron silicate and makes up about 38 percent of Earth’s volume. Scientists require a natural sample of a mineral before it can be officially named; because the Earth’s bridgmanite is entombed 660 to 2,900 kilometers below the surface and doesn’t survive the trip up, it therefore has been nameless for decades. Scientists have fruitlessly hunted for traces of bridgmanite forged during powerful meteorite impacts that mimic the high temperatures and pressures deep inside Earth.
In the Nov. 28 issue of Science, mineralogist Oliver Tschauner of the University of Nevada, Las Vegas and colleagues describe bridgmanite found inside a meteorite that slammed into a remote part of Queensland, Australia in 1879. The meteorite was highly shocked, meaning it endured high temperatures and pressures as it slammed into other rocks in space. The researchers estimate that the impact generated temperatures of around 2,000° Celsius and high pressures crushing each square centimeter of rock. Those impacts can create shock veins of minerals within the meteorites.
Under the rules of the International Mineralogical Association, scientists can name a mineral only once they’ve analyzed a natural sample. To be considered a mineral, it must be verified as a solid material with a distinct chemical composition and crystalline structure. After five years of work, including multiple experiments, Tschauner sent data for review to the International Mineralogical Association’s Commission on New Minerals, Nomenclature and Classification. The commission approved the mineral and new name on June 2. The newfound bridgmanite will help scientists better understand the churning of Earth’s mantle, according to the scientists on the team.