Bridgmanite, long sought, now found in 1879 meteorite
O. Tschauner et al/Science 2014
A space rock has helped scientists characterize, and finally name, the planet’s most common mineral.
The newly christened bridgmanite, named for high-pressure physicist Percy Bridgman, is a high-density form of magnesium iron silicate and makes up about 38 percent of Earth’s volume. Scientists need a natural sample of a mineral before it can be officially named. However, Earth’s bridgmanite is entombed 660 to 2,900 kilometers below the surface, and doesn’t survive the trip up. For half a century 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 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 researchers estimate that the impact generated temperatures of around 2,000° Celsius and pressures greater than but akin to an adult blue whale’s mass crushing each square centimeter of rock.
The newfound bridgmanite will help scientists better understand the churning of Earth’s mantle, the team says.
O. Tschauner et al. Discovery of bridgmanite, the most abundant mineral in Earth, in a shocked meteorite. Science. Vol. 346, November 28, 2014, p. 1100. doi: 10.1126/science.1259369.
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