Western Australia’s Argyle mine was between nature’s preeminent treasure troves for almost 40 many years. At its peak, Argyle developed much more colored diamonds than any place else on Earth and gained an specifically sparkling reputation for its unparalleled cache of pink diamonds.

Scientists have expended many years striving to unravel the origins of Argyle’s glimmering gems. Now, by courting minerals in the mine’s volcanic rock, experts believe they may well have finally pieced collectively the process that made the deposit about 1.3 billion yrs back. In a paper posted on Tuesday in Character Communications, the workforce posits that the break up of an early supercontinent lifted Argyle’s salmon-colored stones from crushing depths toward Earth’s floor.

Located 2,200 kilometers northeast of Perth, Australia, in the country’s rugged Kimberley location, Argyle mine once lined an location the sizing of 94 soccer fields. Between its opening in 1983 and closure in 2020, when mining the gems there was no for a longer time economically viable, Argyle manufactured far more than 865 million karats of rough diamonds. Most of these stones come in pale shades of yellow or brown. But a smaller proportion of the site’s diamonds radiate abundant pinks, purples or reds. More than 90 % of the world’s pink diamond supply—including the nearly 13-karat Pink Jubilee—has appear from Argyle.

The pink hue of Argyle’s most lavish diamonds is joined to destruction they underwent deep within just the earth. According to Hugo Olierook, a geologist at Curtin College in Perth and direct writer of the new research, these diamonds start out colorless. But huge tectonic force from colliding continents can alter the stones’ crystal composition, unlocking the prospective colours concealed inside. “The diamonds are currently being compelled to bend and twist,” Olierook claims. “If they’re twisted just a small bit, it will convert some of these diamonds pink.” Even further twisting will make them turn into brown.

Argyle’s diamonds took on their pink and brown tints around 1.8 billion years ago, when a piece of what is now western Australia smashed into the northern Australian plate and warped the region’s rock. But this only clarifies section of Argyle’s origin story. When the continents collided, the area’s diamonds were buried in the mantle, hundreds of kilometers beneath Earth’s area. If the crystals had been nearer to the surface area, their carbon atoms would have been compressed into a different construction, reworking them from shimmering diamonds to lumps of dark gray graphite.

A volcano was vital to provide the molten diamonds up from our planet’s mantle. “You have to have some kind of tectonic induce to deliver them up to the surface,” Olierook states. As the melt rises, carbon dioxide and steam increase, sparking an eruption that he compares to popping a champagne cork. At Argyle, this eruption probably transpired at a beach front, where sand and seawater interacted with volcanic rock known as lamproite.

To figure out when the eruption occurred, the workforce sliced two slim sections of Argyle’s volcanic rock and polished them down to a minuscule width. Analyzing the sample’s mineral makeup beneath a microscope, the scientists were being ready to pinpoint sand grains from Argyle’s historic beach and to day them with the support of radioactive elements they contained. By dating the youngest sand grains, the experts had been in a position to estimate when the beach front was buried in lava. They also applied small lasers to ascertain the ages of titanite minerals, which formed in the rock when the magma melded with quartz in the beach sand.

Comparing the ages of the youngest sand grains and the oldest titanite crystals allowed the scientists to estimate that the eruption at Argyle happened among 1.3 billion and 1.26 billion decades back. This age range was more mature than former estimates, which astonished Olierook and his colleagues. “We had a betting pool likely, and no one bought 1,300 [million years],” he states. “That was one particular of individuals glass-shattering times.”

That eruption timing corresponds to a risky interval in Earth’s tectonic heritage when a person of the initial supercontinents, known as Nuna, was splintering aside. The group posits that this instability may have reopened a seam along the continental boundary exactly where Argyle is now situated. This in flip sparked the volcanic activity that brought the diamond-bearing soften toward the area, making Argyle’s expansive diamond deposits.

The new time estimates increase essential context for knowing the volcanic eruption at Argyle, says Evan Smith, a researcher at the Gemological Institute of The usa, who researches the geology of diamonds but was not included in the new study. “The former age constraint for Argyle was more youthful, and it was a great deal significantly less obvious how to frame the eruption in a broader geological context,” Smith suggests. He thinks the new research adds remarkable evidence that these “eruptions are relevant to greater procedures that have an impact on entire continents somewhat than remaining isolated, random burps of magma.”

Olierook thinks similar situations could have transpired at other continental boundaries about the world. Most diamond-bearing deposits are uncovered in the middle of continental plates where rock is uncovered. This tends to make Argyle an outlier. When the mine was first found out, most geologists considered that exploring for diamonds along continental plate boundaries—which are frequently uplifted by ancient mountain belts and buried beneath soil and sand—was futile.

While gem mining in these locations remains complicated, Olierook believes there are lots of diamonds to be identified in the tough. “I consider all of them will host some sort of coloured diamonds,” he says. “They may perhaps all be brown, but with a minor little bit of luck, there could be a number of pinks in there.”