Polished colored diamonds from the Argyle diamond deposit are shown. The now closed mine in Western Australia was the source of 90% of the world’s pink diamonds.
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Pink diamonds are extremely rare and sought after – a now closed mine in Australia was the source of 90% of the colored gems. Polished pink specimens of the highest quality can be sold for tens of millions of dollars. But a discovery made in the same area could help reveal new deposits of the jewels, researchers say.
Scientists studying Western Australia’s Argyle diamond deposit, where the mine was located, said they now have a better understanding of the geological conditions needed for pink diamonds and other color varieties to form, according to a study published Tuesday in the journal Nature communication.
Using lasers to analyze minerals and rocks extracted from the Argyle deposit, the researchers found that the pink diamond-rich site was formed during the breakup of an ancient supercontinent, called Nuna, about 1.3 billion years ago.
“While the continent that would become Australia did not break apart, the area where Argyle lies was stretched, including along the scar, creating holes in the Earth’s crust for magma to shoot through to the surface, bringing with it pink diamonds,” said lead study author Dr Hugo Olierook, a researcher at Curtin University’s John de Laeter Center in Perth, Australia, in a press release.
The Argyle diamond mine is located in the remote Kimberley region in the far north-east of Western Australia.
Most diamond deposits are found in the center of ancient continents – in volcanic rocks that have rapidly transported diamonds from deep within the Earth’s interior to the surface.
However, for diamonds to spin pink or red, they must be subjected to intense forces from colliding tectonic plates, which twist and bend their crystal lattices. Most brown diamonds is also formed in this way.
At Argyle, this process occurred about 1.8 billion years ago when Western Australia and Northern Australia collided, turning the once colorless diamonds pink hundreds of miles below the Earth’s crust.
But how did these colored diamonds make their way to the surface? The research team found that the Argyle deposits were 1.3 billion years old, from a time when an ancient supercontinent known as Nuna was breaking up into fragments.
Pink diamonds from the Argyle diamond mine were formed when an ancient supercontinent was breaking up into fragments, according to a new study.
Supercontinents, which form when several continents join together to form a single land mass, have occurred several times in Earth’s geological history.
“Using laser beams smaller than the width of a human hair on rocks supplied by Rio Tinto (the company that owned the mine), we found that Argyle was 1.3 billion years old, which is 100 million years older than previously thought, meaning it is 1.3 billion years old. would likely have formed as a result of an ancient supercontinent breaking up,” Olierook said.
The authors suggested that the breakup of Nuna may have reopened the ancient junction left by the colliding continents, allowing diamond-bearing rocks to travel through this region to form the Great Diamond Deposit.
This chain of events, according to the study, suggested that the transitions between ancient continents may be important for finding pink diamonds — and may guide exploration for other deposits.
“Most diamond deposits have been found in the center of ancient continents because their host volcanoes tend to be exposed at the surface for explorers to find,” Olierook said.
“Argyle is at the suture of two of these ancient continents, and these edges are often covered in sand and soil, leaving the possibility that similar pink diamond-bearing volcanoes still sit undiscovered, including in Australia.”