Bridgmanite, the most abundant mineral on Earth, has now been studied in detail for the first time. This provides the fist confirmation of a basic theory about our planet.
Geologists have suspected for decades that the mantle of the Earth, laying beneath the crust, was largely composed of a strange mineral. Experiments were performed to recreate the high temperatures and pressures in the mantle to show that the region was likely rich in Silicate-perovskite minerals. This class of chemicals contains silicon and other atoms arranged in a box-like shape called a perovskite structure.
Silicate-perovskite is the technical name first given to the predicted material by geologists. The nomenclature reflects the chemical makeup and crystal structure of the material. That name has now been replaced by bridgmanite.
The substance is the most common mineral on the Earth, but it remains hidden deep beneath the surface of the Earth, in our planet's mantle, as much as 400 miles underground. Drilling to these depths is impossible with today's technology, and the distance is too great for significant amounts of the deposits to rise to the surface. Although artificially-created samples of Bridgmanite have been examined in the laboratory, this is the first time it has been identified in its natural form and studied.
"The most abundant mineral of the earth now has an official name," Chi Ma of CalTech, and one of the leaders of the five-year-long study, said.
An asteroid, estimated to be 4.5 billion years old, crashed into Australia in 1879. Stuck between other layers of rocks, geologists found the rarely-seen mineral in the Tenham Meteorite. Researchers believe high-speed collisions with other asteroids over billions of years could have subjected the rocky body to extremely high pressures.
"This finding fills a vexing gap in the taxonomy of minerals," Oliver Tschauner, associate research professor at the University of Nevada-Las Vegas, who identified the substance along with Ma, told the press.
Tschauner first identified areas of the meteorite that could hold traces of the elusive mineral, using X-ray diffraction mapping. An electron microprobe was then employed on these areas by Ma, searching for the telltale crystals of the substance. Details of the structure were then revealed through diffraction of X-rays.
Bridgmanite is named in honor of Percy Bridgman, winner of the 1946 Nobel Prize for Physics, for his work on high-pressure systems.
"Each of the new extraterrestrial minerals reveals distinctive forming environments, providing new insights into nebula or parent-body processes," Ma wrote on his CalTech biography.
The International Mineralogical Association's Commission on New Minerals, Nomenclature and Classification approved the new mineral name on 2 June.
