Scientists have discovered calcium silicate perovskite, for the first time, at Earth’s surface. The fourth most abundant mineral on our planet was found in a diamond. According to the scientists, it is hard to keep the mysterious mineral stable at Earth’s surface.
“Nobody has ever managed to keep this mineral stable at Earth’s surface,” Graham Pearson, from the University of Alberta’s Department of Earth and Atmospheric Sciences and Canada Excellence Research Chair Laureate said in a statement. He added that the mysterious mineral is found 435 miles deep in the Earth’s mantle.
“The only possible way of preserving this mineral at the Earth’s surface is when it’s trapped in an unyielding container like a diamond,” he explained. “Based on our findings, there could be as much as zetta tonnes (1021) of this perovskite in deep Earth.”
However, Pearson and associates from the University of British Columbia discovered that the calcium silicate perovskite found within a diamond, was mined about half a mile beneath Earth’s surface. It was found at South Africa’s Cullinan Mine, best known for where two of the largest diamonds in the British Crown Jewels were mined from. Pearson explained that the diamonds found in that mine, aside from its commercial value, have a vast scientific value, as they give a lot of information regarding the deepest parts of the Earth, including its core.
“A notable exception is the high-pressure perovskite-structured polymorph of calcium silicate (CaSiO3). This mineral—expected to be the fourth most abundant in the Earth—has not previously been found in nature,” researchers wrote in their study.
According to the scientists the diamond containing the mysterious mineral would be capable of sustaining more than 24 billion pascals of pressure, equivalent to 240,000 atmospheres. Most diamonds are formed at 95 to 125 miles deep, while the diamond in question was found 435 miles below Earth’s surface.
“Diamonds are really unique ways of seeing what’s in the Earth,” said Pearson. “And the specific composition of the perovskite inclusion in this particular diamond very clearly indicates the recycling of oceanic crust into Earth’s lower mantle. It provides fundamental proof of what happens to the fate of oceanic plates as they descend into the depths of the Earth.”
“And it’s a nice illustration of how science works. That you build on theoretical predictions in this case from seismology and that once in a while you’re able to make a clinching observation that really proves that the theory works,” said Pearson.
According to the statement, Pearson is one of the best diamond researchers in the world, as he was behind the vast 2014 discovery of ringwoodite, which is Earth’s fifth most abundant mineral. It was found in a diamond that suggested evidence of a huge reservoir of water in silicate rocks in Earth’s mantle.
He also collaborated with an international team of researchers on many projects including one of the best X-ray crystallographers in the world.
The research titled “CaSiO3 perovskite in diamond indicates the recycling of oceanic crust into the lower mantle,” appears in the journal Nature on March 8.