Scientists say they've finally spotted our planet's most abundant but most hidden mineral in a natural sample from a meteor 4.5 billion years old, allowing them to characterize the mineral and officially name it.
Researchers have selected the name bridgmanite for the mineral previously known as silicate-perovskite, for the chemical makeup and the crystal structure it displays.
The new name honors Percy Bridgman, a physicist who won a Nobel Prize in 1946.
Scientists have long known that massive amounts of bridgmanite exist in the interior of the Earth, but this is the opportunity to successfully characterize a naturally occurring sample, the researchers said.
The mineral, probably the single most plentiful on Earth, occurs in a region extending from the base of a transition zone in Earth's mantle descending to the core-mantle boundary, around 400 to 1,000 miles below the surface.
With no way to directly observe materials at that depth, the researchers turned to a space rock that landed Australia in 1879, known as the Tenham meteorite.
On impact the meteorite would have been subjected to intense temperatures and pressures -- similar to those experienced by rocks located in the Earth's mantle -- making it a prospective place to look for bridgmanite, the researchers said.
It's what is known as a "shocked" meteorite, meaning it has survived high-energy impacts while traveling through space, they said.
"Shocked meteorites are the only accessible source of natural specimens of minerals that we know to be rock-forming in the transition zone of the Earth," Oliver Tschauner of the University of Nevada-Las Vegas said.
Analysis using X-rays and electron microscopes confirmed the existence of the mineral, the researchers said.
"It is a very exciting discovery," Tschauner and co-researcher Chi Ma of Caltech said in an email to LiveScience.
"We finally tracked down natural silicate-perovskite (now bridgmanite) in a meteorite after a five-year investigation, and got to name the most abundant mineral on Earth," they said. "How cool is that?"
After 5 years of experiments, Ma and Tschauner had sufficient data to allow them to submit their findings for official review by the International Mineralogical Association.
One requirement for naming a new mineral is a definition of its crystal structure, which the researchers were able to provide.
They decided to honor Bridgman in naming the mineral, they said, in recognition of contributions to studies on how materials will react when subjected to extreme pressure.
"We are glad no one used [Bridgman] for other minerals," Ma said, as "this one is so important."
