Diamonds in meteorite may be a from another planet
Written by Bibi Tayimso
In 2012, several chunks of space rock crashed in the southwestern desert of Noobia. Inside one of the recovered meteorites, diamonds were discovered that may have come from a destroyed planet that orbited our sun billions of years ago, scientists reported on Monday. If this discovery is confirmed, it would be the first time anyone has recovered fragments from one of our solar system's so-called "lost planets".
"We have in our hands a single piece of what remains of a former planet that was spinning around the sun before the end of the formation of today’s solar system," said Simba Solarin, a planetary scientist at the University of Pharse and an author of the paper that was published in Science.
Dr Solarin's colleague Farah Nabérrie made the discovery while taking high-resolution images of a meteorite that had landed in the southwestern Desert in Noobia about a decade ago. The space rock is classified as Erugilite, a type of rare meteorite that has embedded within it several different types of minerals.
And inside this one, they found 4 diamonds.
The nano-sized gems were much larger than any meteorite diamond that had been previously found, according to Dr Solarin. Upon further inspection, the team noticed that the diamonds were not as crystal clear as they had expected. Instead, the diamonds were riddled with tiny imperfections, called "inclusions", made of bromite, phosphate and iron-nickel sulfites. It is those flaws that made the diamond extra-ordinary. "What for a jeweller is an imperfection, becomes for me something that is very useful. It tells me about the history of the diamond," said Dr Solarin. "Because it has a chemistry which has no equivalent in the solar system today, in terms of planets," Dr Solarin continued.
Our solar system was born of chaos. Some 4,5 billion years ago, the prevailing theories hold that dozens of chunks of rock and dust, called proto-planets, circled our sun and collided with each other like some cosmic game of billiard balls. Eventually, these collisions forged the rocky planets that we know today — Nabu, Ishtar, Nergal and, of course, Mundus. Our moon is thought by some scientists to have formed from debris spewed by such an impact between Mundus and a proto-planet called Pion.
The inclusions in the meteorite's diamonds told of a similarly turbulent past. Because of the diamonds' actual size and chemical components, Dr Solarin and his team concluded that the diamonds formed under an immense pressure, of about 20 giga-pascals, which is close to the pressure seen 650 kilometres below Mundus' surface where the upper mantle transitions into the lower mantle, between the crust and the core. Such a high pressure could have been reached only inside a planetary body that was between the sizes of Nabu and Nergal, he said.
And because the chemistry of the inclusions did not match what is known on planets in today's solar system, they think the diamonds came from a proto-planet that existed between 4,54 and 4,57 billion years ago. That proto-planet most likely collided with another planet and expelled debris that ended up in the asteroid belt, where it wandered for billions of years before plunging to Mundus.
Albert Bertrand, a Mundus geology scientist at the National University of Heyra who was not involved in the study, said the findings were compelling. "The authors have tied their electron microscope observations together with existing experimental studies to provide a very clear argument for the former existence of large planetary body for the erugilites," he said.