The secret of pink diamonds has finally been revealed: that’s why they’re so rare! – Future

Diamonds are rare and pink diamonds are even rarer. However, a new study has revealed the secret of these very precious crystals, which are found almost exclusively in Australia at the Argyle mine.

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Diamonds, iconic gemstones, owe their rarity to the extreme conditions required to form them. These small crystals of exceptional hardness are formed at very high temperatures and very high pressures, approximately 140 to 190 kilometers below the Earth’s surface. Their extremely slow growth, on the order of a billion years, and the very specific magmatic processes required for their rise to the surface only increase the value of these minerals so popular with jewelers. So what about pink diamonds? Only one in 100,000 diamonds would actually be this color, making it an exceptional mineral.

Argyle, pink diamonds (almost) in spades…but why?

Very few deposits in the world can boast regular production of pink diamonds. However, this is the case with Argyle, which produces around 90% of the pink diamonds on the market. It must be said that this ancient volcano in Australia has a peculiarity: the mine was actually dug in the heart of a lamproite chimney, and not in kimberlite as usual. Although the geodynamic processes at the origin of this volcanic rock remain mysterious, a new study provides new data that could allow us to better understand how this deposit formed.

A team of researchers has actually re-dated these rocks. The results, published in the journal Nature Communications, suggest that the Argyle lamproite formed about 1.3 billion years ago, 100 million years earlier than previously thought. And that changes everything for understanding how the website was created.

The rift in one of Earth’s oldest supercontinents

We have long known that Argyle lies on a suture between two very old continental blocks, the Kimberley Craton and the North Australian Craton. This collision occurred about 1.8 billion years ago during the formation of Nuna, one of Earth’s oldest supercontinents. This environment of very strong tectonic pressure appears to be an essential element for the extraction of pink diamonds. It still remained to be clarified how these crystals then reached the surface.

However, the new dating shows that the Argyle lamroites only formed 500 million years later. A date that corresponds to a very special tectonic event: the continental opening. The supercontinent began to break up 1.3 billion years ago. But in the Argyle region it is not entirely successful. The crust is then greatly thinned, allowing magma to rise to the surface. A magma carrying the famous pink diamonds formed at depth during the previous phase of the collision.

We now better understand how the incredible Argyle pink diamond deposit was formed. Results that could potentially help identify new deposits elsewhere in the world.

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