The Cullinan mine, located on a diamond-bearing kimberlite pipe in the Gauteng province of South Africa, is the world’s richest source of rare blue diamonds and has produced more than a quarter of the world’s diamonds that are greater than 400 carats. The massive mine is also a scientific treasure trove. As scientists report in Nature on Wednesday, the Cullinan mine’s massive diamonds aren’t just a luxury item but a clue to what’s happening at the deep core of the Earth.

In the paper, a team of international researchers report the rare scientific discovery they found in the mine: a “super-deep” diamond encasing the mineral calcium silicate perovskite (CaSiO3), which is the fourth-most abundant mineral in the Earth but has never been found in nature until now. Super-deep diamonds, the researchers tell Inverse, are a classification reserved for those rare diamonds formed between 200 to 1,000 kilometers into the lower mantle, so they are super rare, too.

“This was very special because this mineral had been theoretically predicted, but it was not thought possible to see it preserved at the Earth’s surface for observation and measurement,” University of Alberta researcher and study co-author Graham Pearson, Ph.D., tells Inverse. Pearson is well-known as one of the world’s leading diamond researchers. “Finding a natural object that has never been seen by anyone before is always exhilarating! It’s what most natural scientists dream about.”

A cartoon illustrating the findings.

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Pearson and his team determined that the super-deep diamond originated around 760 kilometers below Earth’s surface — much deeper than most diamonds, which on average form between 150 to 200 kilometers below ground. Natural diamonds are formed when carbon molecules form highly organized “lattices” at high temperatures and pressure. Because this particular diamond was formed so far below the surface, Pearson estimates, it would have sustained more than 24 billion pascals of pressure. It was likely that it was able to incorporate the precious CaSiO3, which can only exist at the very high pressures close to the Earth’s crust. The inclusion of the precious CaSiO3 inside the diamond was confirmed by X-ray measurements made by the paper’s primary author, University of Padova professor of geoscience Fabrizio Nestola, Ph.D.

It’s very energetically difficult for minerals to rearrange their atoms to other structures, Pearson explains. So, once a diamond becomes a diamond, it’s not going to suddenly switch up its carbon lattice to turn into graphite, even though it might “want” to in the relatively low-pressure atmosphere of the Earth’s surface. This was a good thing for Pearson and his co-authors, because CaSiO3 is only stable at the extremely high pressure that exists over 500 kilometers below the Earth’s surface. There, it’s extremely abundant — the scientists estimate there could be 1,021 tonnes of perovskite in deep Earth — but in order for it to rise up to the surface, it needs a vehicle. Fortunately, it found one far closer to its home, the extremely hard, protective containers we know as diamonds.

“Only the super-strong nature of the diamond, and the particular nature of the fast eruption of the host kimberlite, in this case, provided a favorable set of circumstances that led to the preservation of this mineral,” says Pearson. “Many people predicted that we would never actually see a natural version of this mineral at the Earth’s surface because it is so unstable.”

The Cullinan mine in South Afica.

While the diamonds of the Cullinan mine are considered the world’s most commercially valuable, they’re also the most scientifically valuable. Diamonds, in general, are valued among geoscientists because they “provide access to the deepest intact material from the Earth’s interior through the minerals contained within their volumes,” the authors write.

In turn, the super-deep diamonds of Cullinan are so precious because they are some of the deepest physical samples of Earth’s interior ever found. Here, the perovskite structure within the diamond “very clearly” provides proof that as oceanic plates are pulled into Earth’s lower mantle, that crust transitions into a new mineral.

Next up for this diamond is further analysis by scientists at the University of British Columbia who will attempt to learn more about its age and origin. Understanding how the formation of super-deep diamonds differs from diamonds created at more shallow depths will help scientists paint a better picture of the dynamics and chemistry of the molten mess of minerals found deeply embedded in the planet’s mantle.

On Monday, scientists revealed the first images of a human inside the world’s newest total body scanner, called EXPLORER. The name is fitting because this scanner really leaves absolutely nothing to the imagination, tracking the way drugs and disease progress through every nook and cranny in the body.

Designed by biomedical engineering professor Simon Cherry, Ph.D., and biophysicist Ramsey Badawi, Ph.D. at University of California, Davis, this scanner produces images that look like a hybrid between a PET scan (which is often used to find tumors) and an X-ray, all in ghostly black and white. But what’s interesting about EXPLORER, which will be officially unveiled at the Radiological Society of North America meeting on November 24th, isn’t that it produces detailed images of tissues or bones. Cherry tells Inverse that it can also create 3D movies showing where certain drugs may end up in the body.

NASA’s InSight Mars lander successfully touched down on the red planet on Monday, but its mission is just beginning. After a harrowing descent, as the dust began to settle and NASA officials celebrated the feat, InSight sent back its first image of the monochrome landscape — clearly visible, though somewhat obscured by a dusty lens. This quick turnaround may suggest that InSight is about to unlock the secrets of the red planet any second now, but there’s a good reason that the process will actually move pretty slowly during the early days of its mission.

This December, Inverse is counting down the 25 most WTF moments in the world of science in 2018. Some are gross, some are amazing, and some are just, well, WTF. There are stories on kangaroos that got high on DMT, surprising research into fake news, a weird fact about early memories, a scientific study on booze, an explanation for why you’re sad after sex, and an appreciative ode to Neanderthals.

There’s no more epic way to celebrate the International Space Station’s golden birthday than with a cinematic time lapse.

Brought to Earth by European Space Agency astronaut turned time lapse expert Alexander Gerst, the ESA released its longest continuous time lapse filmed from the ISS yet, in honor of the weightless laboratory’s 20th anniversary on November 20. In just under 15 minutes, Gerst takes viewers on an awe-inspiring tour of our blue dot from 400 kilometers — about 249 miles — above.