Pink diamonds are extremely rare and sought after – 90% of the colored gems come from now closed mines in Australia. Top-quality polished pink specimens can fetch tens of millions of dollars. But researchers say discoveries in the same area could lead to new deposits of jewelry.
Scientists studying the Argyle diamond deposit in Western Australia, where the mine is located, say they now have a better idea of the geological conditions needed to form pink diamonds and other colored varieties, according to a study published Tuesday in the journal Nature Communications. OK I understand. Using laser analysis of minerals and rocks from the Argyll deposit, researchers discovered that the pink diamond-rich site formed during the collapse of an ancient supercontinent called Nun about 1.3 billion years ago. “Without rifting, the area where Argyle is located is stretched, including along the scar, creating holes in the crust for magma to flow to the surface, creating the pink diamonds,” says lead study author Dr. Hugo. Ollie Rooker, a researcher at the John Dellat Center at Curtin University in Perth, Australia, said in a press release.
Dig up pink diamonds.
Most diamond deposits are located in the center of ancient continents in volcanic rocks that quickly transported diamonds from the depths of the Earth to the surface.
But for a diamond to turn pink or red, it must withstand the powerful forces of tectonic plate collisions that twist and bend its crystalline lattice. Most brown diamonds also form this way.
At Argyll, this process occurred about 1.8 billion years ago when western and northern Australia collided, turning the once colorless diamonds pink hundreds of miles beneath the Earth’s crust. But how do these colored diamonds get to the surface? The team discovered that the Argyle deposit is 1.3 billion years old, when an ancient supercontinent called Nuna broke up. Supercontinents, which form when several continents join together to form a single land mass, have appeared many times in Earth’s geologic history.
“Using a laser beam less than the width of a human hair on a rock provided by Rio Tinto (the company that owns the mine), we discovered that Argyll is 1.3 billion years old, 100 million years older than previously thought. This means that it most likely resulted from the collapse of an ancient supercontinent,” Olluk said. The collapse of Nuna may have reopened ancient joints left by continental collisions, allowing diamond-bearing rocks to move through the area and form large diamond deposits, the authors suggest.
This sequence of events suggests that the ancient continental nodes may have been important in the search for pink diamonds and could guide the exploration of other deposits, the study said. “Most diamond deposits were found in the center of ancient continents because their host volcanoes were often exposed to the surface for explorers to discover,” Olluk said.
“Argyles is located at the seam of two ancient continents, and these edges are often covered with sand and soil, so it is possible that similar pink diamond volcanoes remain undiscovered, including in Australia.”