2023-09-19 15:00:00
The pink diamond recipe? A pinch of carbon in the depths of the Earth, the force of tectonic plates colliding – for color – and… a third “key ingredient”, which Australian researchers have just revealed in an article (Nature CommunicationsSeptember 19).
To find out, the authors examined samples from the old Argyle mine. Located in the far north of the state of Western Australia, this dormant volcano contained an enormous deposit of diamonds – stones with exceptional hues ranging from red to blue to pink.
Considered the largest natural source of diamonds in the world in some years – and having produced more than 90% of pink diamonds to date, the Argyle mine was closed in 2020 after the resource was depleted.
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A 1.3 billion year old volcano
“Using laser beams finer than a human hair on rocks provided by [le groupe minier] Rio Tinto, we discovered that the Argyle deposit was 1.3 billion years old, 100 million years older than previously thought.”explains Dr Hugo Olierook, researcher at Curtin University and first author of the study, in a press release.
And it is precisely this “small” hundred million years of difference which, according to him, makes all the difference: “this means that Argyle probably formed following the breakup of an ancient supercontinent”he deduces.
The third ingredient for finding pink diamonds would therefore be, according to the study, a “stretching” continental masses during the breakup of the continents several hundred million years ago. This stretching would have created “breaches” in the earth’s crust, through which diamond-bearing magma could rise to the surface.
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Thus, the Argyle mine is located precisely where the Kimberley region (northern Western Australia) and the rest of the Australian continent “struck” in an even more distant past, specifies the press release. The collision would have created a sort of “scar” in the earth, which has never completely “cured”.
Then, when the continents were torn apart, Australia – which could then have fragmented into two parts – finally broke apart. “stretched” at this point of weakness. “This created breaches in the Earth’s crust allowing magma to rise to the surface, bringing with it pink diamonds”describes Dr. Olierook.
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A treasure under your feet?
For the authors, this work opens up the prospect of one day finding the “next Argyle”, that is to say a pink diamond mine as prolific as the Australian site. Without, however, underestimating the obstacles on the path to such a discovery.
“Most diamond deposits have been discovered in the middle of ancient continents, because the volcanoes that host them tend to be more exposed on the surface, so explorers have been able to find them“, recognizes the first author.
On the other hand, “Argyle lies at the junction of two ancient continents; these junctions are often covered in sand and earth”. A treasure may be hidden under your feet, who knows…
On the same topic :
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