Diamonds From Meteorite May Be From Lost Planet, Study Says

Federico Mansilla
Abril 18, 2018

According to researchers from the École Polytechnique Fedérale de Lausanne, the diamonds from an asteroid called Almahata Sitta, which fell into the Nubian desert in October 2008, formed at pressures consistent with early Solar System protoplanets. Many of these protoworlds collided, their fragments forming new planets and moons.

Most planetesimals stay that size. Earlier theories held that these protoplanets were either absorbed into other planets or satellites or ejected from the solar system entirely, but the discovery of these deposits points to a third possibility.

"We have in our hands a remnant of this first generation of planets that are missing today because they were destroyed or incorporated in a bigger planet.", Gillet said.

And the asteroids still floating around the Solar System, astronomers believe, are the leftovers from those days - from the repeated collisions that blasted material back into space.

But that's not the only thing that made Almahata Sitta special.

The Almahitta Sitta - named after the place in Sudan where witnesses saw it explode in the sky - is an extremely rare type of meteorite known as an ureilite.

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Previous explanations for the diamonds within ureilites include powerful impacts, such as collisions between asteroids.

The presence of these particular inclusions suggest the diamonds were formed under significant pressure, roughly 20 giga-Pascals.

Nor, the researchers said, could chemical vapour deposition have produced the crystal sizes - which leaves static high pressure. Using transmission electron microscopy and electron energy-loss spectroscopy, the team analysed the Almahata Sitta diamonds to see what these mineral inclusions were.

They concluded the precious stones must have formed at pressures that could only have existed on a long-lost Mars- to Mercury-sized planet.

The measurements provide "the first compelling evidence for such a large body that has since disappeared", the research team wrote in a paper published in the journal Nature Communications.

Planetary formation models suggest that in the early solar system, the terrestrial planets-Mercury, Venus, Earth and Mars-were formed after the gradual merger of tens of proto-planets in a series of high-energy impacts.

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