Study: Diamond from the sky may have come from 'lost planet'

April 17, 2018 by Frank Jordans
Study: Diamond from the sky may have come from 'lost planet'
Photo provided by Hillary Sanctuary of EPFL shows a thin slice of the meteorite sample from a meteorite that fell to Earth more than a decade ago providing compelling evidence of a lost planet that once roamed our solar system, according to a study published Tuesday. (Hillary Sanctuary/EPFL via AP)

Fragments of a meteorite that fell to Earth about a decade ago provide compelling evidence of a lost planet that once roamed our solar system, according to a study published Tuesday.

Researchers from Switzerland, France and Germany examined diamonds found inside the Almahata Sitta meteorite and concluded they were most likely formed by a proto-planet at least 4.55 billion years ago.

The diamonds in the meteorite, which crashed in Sudan's Nubian Desert in October 2008, have tiny crystals inside them that would have required great pressure to form, said one of the study's co-authors, Philippe Gillet.

"We demonstrate that these large diamonds cannot be the result of a shock but rather of growth that has taken place within a planet," he told The Associated Press in a telephone interview from Switzerland.

Gillet, a planetary scientist at the Federal Institute of Technology in Lausanne, said researchers calculated a pressure of 200,000 bar (2.9 million psi) would be needed to form such diamonds, suggesting the mystery planet was as least as big as Mercury, possibly even Mars.

Scientists have long theorized that the early solar system once contained many more planets—some of which were likely little more than a mass of molten magma. One of these embryo planets—dubbed Theia—is believed to have slammed into a young Earth, ejecting a large amount of debris that later formed the moon.

Inclusion trails imaged inside diamond fragments. a HAADF-STEM image from diamond segments with similar crystallographic orientation. Dashed yellow lines show the diamond–graphite boundaries. b High-magnification image corresponding to the green square in a. Diamond and inclusion trails are cut by a graphite band. The dashed orange line shows the direction of the inclusion trails. Credit: Nature Communications (2018). DOI: 10.1038/s41467-018-03808-6

"What we're claiming here," said Gillet, "is that 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."

Addi Bischoff, a meteorite expert at the University of Muenster, Germany, said the methods used for the study were sound and the conclusion was plausible. But further evidence of sustained high pressure would be expected to be found in the minerals surrounding the diamonds, he said.

Bischoff wasn't involved in the study, which was published in the journal Nature Communications.

Explore further: 'Super-deep' diamonds may hold new information about Earth's interior

More information: Farhang Nabiei et al. A large planetary body inferred from diamond inclusions in a ureilite meteorite, Nature Communications (2018). DOI: 10.1038/s41467-018-03808-6

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Bandit4
5 / 5 (2) Apr 17, 2018
I think the most important part of this article was; "...methods used for the study were sound and the conclusion was plausible. But further evidence of sustained high pressure would be expected to be found in the minerals surrounding the diamonds...".

While it would be great for science to find physical evidence of proto-planets. The article (I haven't read their actual report) draws too convenient a conclusion. How did they rule out "shock"?

Interesting stuff...thanks.
Da Schneib
5 / 5 (2) Apr 17, 2018
The pressures listed in the article sound pretty impressive, but impacts can generate pressures more than ten times greater than the 1.3 GPa (that's what 200,000 psi converts to) listed here. I'll need to see some more compelling evidence than is presented here to buy this "lost planet" hypothesis.
Rooti
5 / 5 (3) Apr 17, 2018
"We demonstrate that these large diamonds cannot be the result of a shock but rather of growth that has taken place within a planet," author and planetary scientist Philippe Gillet reportedly told The Associated Press. (Daily Beast)
mackita
1 / 5 (3) Apr 17, 2018
Henry Moissan was first who prepared the diamonds by fast cooling of liquid carbon-rich iron by water or mercury and extraction the resulting droplets with acid. The diamonds prepared by this simple method were indeed unpure (carbides with low metal content?) - but sometimes quite large...
mackita
1 / 5 (1) Apr 17, 2018
Some of these experiments did look quite suicidal for today's measures:

"Several attempts were tried to use mercury for cooling. In one case the mercury was thrown on the red hot fused liquid. There was a violent explosion. Small hot metallic shots formed and flew all over the room."
...
"After the iron had solidi­fied it was dissolved in hydrochloric acid. It required over a year to complete the solution."
Mimath224
5 / 5 (1) Apr 17, 2018
The pressures listed in the article sound pretty impressive, but impacts can generate pressures more than ten times greater than the 1.3 GPa (that's what 200,000 psi converts to) listed here. I'll need to see some more compelling evidence than is presented here to buy this "lost planet" hypothesis.

And please don't let the Nibiru crowd get hold of it, Ha!
barakn
4 / 5 (4) Apr 17, 2018
Mackita/Zephir, your own link says that later experiments to replicate Moissan and Hershey's method failed, and that rather than synthetic diamonds, the "Gemmological Institute of America had tested five diamonds sent to them by Hershey in 1938, identifying them as natural diamonds and quartz" (which it hints were planted by one of his assistants).
xaga
5 / 5 (2) Apr 17, 2018
The pressures listed in the article sound pretty impressive, but impacts can generate pressures more than ten times greater than the 1.3 GPa (that's what 200,000 psi converts to) listed here. I'll need to see some more compelling evidence than is presented here to buy this "lost planet" hypothesis.

You may have misread that
Gillet, a planetary scientist at the Federal Institute of Technology in Lausanne, said researchers calculated a pressure of 200,000 bar (2.9 million psi)
xaga
5 / 5 (2) Apr 17, 2018
I'm coming up with 20 GPa
Da Schneib
5 / 5 (1) Apr 17, 2018
Hmmm, you're right, @xaga, I did misread it. I also am getting 20 GPa.

However, the range of pressure from impacts runs up to 30 GPa, so I'm still not convinced.
xaga
5 / 5 (2) Apr 17, 2018
@Da Schneib, agreed but 20GPa brings it closer, will be interesting to watch
IwinUlose
5 / 5 (1) Apr 18, 2018
It's also in this article:
"We demonstrate that these large diamonds cannot be the result of a shock but rather of growth that has taken place within a planet," he told The Associated Press in a telephone interview from Switzerland.


It's implied but explained further in the cited paper:
It was thus suggested that individual diamond single crystals as large as 100 μm existed in the sample, which have been later segmented through graphitization7. The formation of such large single-crystal diamond grains along with δ15N sector zoning observed in diamond segments7 is impossible during a dynamic event8,9 due to its short duration (up to a few seconds10), and even more so by CVD mechanisms11, leaving static high-pressure growth as the only possibility for the origin of the single-crystal diamonds.
Da Schneib
1 / 5 (1) Apr 20, 2018
@Iwin, good eye. I didn't bother to check the link to the paper. Bad me.

I will point out however that the evidence for the large single diamond crystals is inferential, so I retain some degree of skepticism. I'd still need to see some stronger evidence.

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