Earth’s most abundant mineral lies deep in the planet’s interior, sealed off from human eyes. Now, scientists for the first time have got a glimpse of the material in nature, enclosed inside a 4.5-billion-year-old meteorite. Consequently, they have characterized and named the elusive mineral. The new official name, bridgmanite, was approved on June 2 for the mineral formerly known by its chemical components and crystal structure, silicate-perovskite. The magnesium-silicate mineral was named after Percy Bridgman, a 1946 Nobel Prize-winning physicist, according to the American Geophysical Union blog.
“The mineral is likely to reside beneath Earth’s surface in an area called the lower mantle, between the transition zone in the mantle and the core-mantle boundary, or between the depths of 416 and 1,802 miles (670 and 2,900 kilometers)”, scientists said.
Oliver Tschauner worked with his colleague, Chi Ma, a senior scientist and mineralogist at the California Institute of Technology in Pasadena, California, to characterize the structure of silicate-perovskite since 2009. However, this year they made a big breakthrough, after analyzing a meteorite which fell in Australia in 1879. The meteorite is formed 4.5 billion years ago.
After thoroughly analyzing it with every available technique, they were finally able to find the bridgmanite veins in the meteorite. Thus, confirming decades of research, they were also able to submit an official name for the mineral, which they did in March 2014.
In March 2014, Tschauner and Ma sent the proposal, which included information such as bridgmanite’s chemical composition, crystal structure, and other physical properties, to the IMA Commission on New Minerals, Nomenclature and Classification (CNMNC), where it underwent a rigorous review.
The CNMNC has strict guidelines for naming new minerals, one of which is the requirement that the crystal structure be defined. As Tschauner and Ma had obtained the mineral’s crystal structure, it was approved as a new mineral.
“It is a really cool discovery,” remarked Chi Ma of Caltech and Oliver Tschauner. “Our finding of natural bridgmanite not only provides new information on shock conditions and impact processes on small bodies in the solar system, but the tiny bridgmanite found in a meteorite could also help investigations of phase transformation mechanisms in the deep Earth. “
“Scientists have been searching for the mineral for a long time, because in order to identify a mineral one must know its chemical composition and crystal structure,” Ma said.
Researchers found the bridgmanite in a meteorite that had fallen on Earth near the Tenham station in western Queensland, Australia in 1879. The meteorite, Ma said, has endured high temperatures and pressures as it slammed into other rocks in space. Those impacts can create shock veins of minerals within the meteorites.
“Scientists have identified high-pressure minerals in its shock-melt veins since 1960s. Now we have identified bridgmanite,” Tschauner said, referring to the Tenham meteorite. The meteorite is considered a chondrite, the most common type of meteorite found on Earth and scientists now think that these meteorites are remnants shed from the original building blocks of planets.
