Deep within the bowels of the Earth, workers are toiling away in one of South Africa’s most famous diamond mines. But while it may seem like just another day on the job, the miners are about to find something extraordinary.




Something so extraordinary, in fact, that no scientist has ever seen above the ground – and that’s despite one of the most common minerals on the planet.



The world around us might seem very familiar, but that doesn’t mean that it doesn’t still hold secrets. Sometimes, those secrets even manage to creep out into the light. This is one of those cases, and it’s a story that delves 400 miles into the crust of the Earth. It’s a tale of jewels and incredible pressure. And it’s unearthed something that no scientist has ever laid eyes on before.



It all starts with a diamond. The Cullinan Diamond Mine, also known as the Premier Mine, is one of the most famous mines in the world – and for very good reason. You see, in 1905, a record-breaking diamond was discovered there. Named in honor of the mine’s chairman, the Cullinan Diamond is still the biggest rough diamond of gem-quality that has ever been found.



Such was the quality of the precious stone, it caught the attention of the British royal family. Now, parts of the Cullinan Diamond – Cullinan I and the Second Star of Africa – adorn two pieces of the Crown Jewels. Other sections of the stone, meanwhile, are privately owned by Queen Elizabeth II. But the Cullinan Diamond, isn’t the only major discovery that’s been made over the lifespan of the Cullinan Mine. In fact, the mine holds a number of records.



A whopping 25 percent of all the of the diamonds in the world greater than 400 carats have been found at the Cullinan Mine. And among the collection lies another record-breaker. Yes, the Cullinan Heritage diamond discovered at the site currently holds the accolade of the most expensive rough diamond ever sold. The stone was sold in 2010 and fetched an incredible $35.3 million at auction. What’s more, the Cullinan Mine is the world’s major source of blue diamonds as well.







However, while the Cullinan Mine may have produced some of the largest and most expensive diamonds in the world, perhaps the most important discovery made there has nothing to do with the size or the worth of the rock. Instead, it concerns something contained within one of the precious stones. A fragment of a mystery that could well have been a billion years in the making.



You’ve probably never heard of calcium silicate perovskite, and with good reason. You see, the chemical compound is normally only found some 400 miles below the surface. It is, however, the mineral is believed to be the fourth most bountiful on the planet. But up until recently, scientists had never actually managed to see a sample of the mineral in the form it holds deep within the Earth’s structure.



But while most diamonds are formed between around 100 to 125 miles beneath the surface of the planet, the one at the heart of this story is different. It’s what scientists call a “super-deep” diamond, and by their best estimates, it was formed more than 430 miles deep. And that fact is the key to the incredibly exciting discovery that lies within the sparkling rock.



You see, the diamond was formed at around the same depth as where you’d expect to find calcium silicate perovskite. That far below the surface the pressure is almost 250,000 times stronger than it is at sea level. And as the immense pressure created the gem, it also trapped a tiny piece of the mineral inside.



So, as the diamond made its way up into the mine, it brought with it a particle of calcium silicate perovskite with it. And according to Graham Pearson of University of Alberta, the discovery of the mineral is a real landmark.



An professor of geochemistry, Pearson is co-author of a study exploring the diamond’s mysteries. In a statement quoted by Newsweek, Pearson said “Nobody has ever managed to keep this mineral stable at the Earth’s surface. The only possible way of preserving [it] at the Earth’s surface is when it’s trapped in an unyielding container like a diamond.” When you look at the numbers concerning calcium silicate perovskite, though, it’s almost incredible that no one had set eyes on it before.



Graham explained in the statement, this time quoted by The Smithsonian, that there could be “as much as zetta tonnes of this perovskite in deep Earth.”.What’s a zetta? Well in simple terms it’s a one followed by 21 zeros. That’s an enormous amount of perovskite lurking below the surface, and it makes the fact that this is the first time that scientists have managed to lay eyes on mineral even more astounding.







But while scientists have always thought perovskite to be abundant, this more accurate estimate has only been possible thanks to the recent discovery at the Cullinan Mine. Indeed, although experts have been trying to study the mineral since the 1960s, perovskite’s unstable nature of has thwarted previous attempts.



As far back as 1975, scientists had managed to synthesize perovskite in the laboratory. Studying naturally occuring samples, however, had proven all but impossible. Instead, scientists had to use something called laser-heated diamond anvil cells to research what happened to the mineral under lower mantle conditions. But with this new discovery, all of that has changed.



Yes, the discovery has led to a whole raft of new ideas and research coming to the surface. One such area of investigation concerns what happens to the crust underneath the ocean. For the first time ever, scientists have a glimpse into how the planet’s carbon cycles work in a practical way. You see, the perovskite in this case started its journey deep beneath the waves.



According to Pearson, the elements that went into making the mineral began life as part of the ocean crust.“When that gets subducted down in the Earth’s mantle,” he went on to explain in the statement, quoted by National Geographic, “it keeps going until it transforms into higher and higher pressure mineral phases.”.Over vast amounts of time, then, the elements are made into something else.



The story of the calcium silicate perovskite found in the diamond is far from over, though. Hopefully, it’s not going to be the last amazing discovery made in precious stones pulled out of the Cullinan Mine. But there’s still a lot of work to do to determine certain things about this most recent find.



For starters, they’re still not sure just how old the diamond is. According to Pearson, the stone could be “quite young [or] a billion years old.” What’s more, this investigation forms just part of a research initiative designed to gather information from diamonds. “We have a program looking at super-deep diamonds with the purpose of obtaining information,” explains Pearson.



Furthermore, Pearson suggests that the find in the diamond mine is a brilliant example of just how modern science works. “You build on theoretical predictions – in this case, from seismology – and once in a while you’re able to make a clinching observation that really proves that the theory works,” he states. And in this case, that clinching observation came courtesy of a glittering gem from hundreds of miles under the ground.

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