They discover the secret of the scarcity of pink diamonds

Researchers found the “secret” of the scarcity of pink diamondswhich are only found almost exclusively in Australiawhich explains its astronomical price, according to a study published on Tuesday.

More than 90% of all existing pink diamonds are mined from the recently closed Argyle mine in northwest Australia.

But no one really knows why they were found in that place, near the sea, when most diamond mines are located in areas far from the coast, as in South Africa and Russia.

An Australian team explains in the journal Nature Communications that these rare minerals were formed thanks to the breakup of Earth’s first supercontinent 1.3 billion years ago.

Both “ingredients” necessary for making a pink diamond were already known, said the study’s first author, Hugo Olierook, of Australia’s Curtin University in Perth.

First ingredient, carbon, located at great depths. At less than 150 km deep, that carbon is a vulgar graphite“that doesn’t look pretty in a wedding ring”says the researcher.

Second “ingredient”a colossal pressure, big enough to change the color of a transparent diamond, but without forcing it too much.

“Press just a little, and it turns pink. But press a little harder and it turns brown,” explains the geologist.

“Like a champagne cork”

The Australian team’s discovery makes it possible to explain the rise of pink diamonds from deep in the Earth’s crust to near the surface.

It was initially thought that the Argyle mine had been formed 1.2 billion years ago, but without explaining how the diamonds could rise without there being an associated geological phenomenon.

The researchers refined the dating of the deposit by measuring the age of tiny crystal elements in a rock from the mine. And they reached 1,300 million years.

An age that corresponds to the fracture experienced by the first supercontinent, called Nuna or Columbia.

Before “all the land masses were together”, according to M. Olierook. The pressure that colored the diamonds occurred with the collisions of the Western and Northern Australian land masses that occurred 1.8 billion years ago.

This mass fractured 500 million years later, and through that place the magma rose, bringing the pink diamonds to the surface, “like a champagne cork”according to Olierook.

A “paradise of pink diamonds”

For 200 years, the search for diamonds was concentrated on continental lands, the scientist observes. And the discovery raises new questions.

The mountain belts arising from the fracture of the Muna supercontinent have the potential to become the “paradise of pink diamonds”, according to the geologist, who cites potential areas in Canada, Russia, South Africa and Australia.

A perhaps premature conclusion, according to John Foden, a diamond expert at the University of Adelaide (South Australia), who was not involved in the study.

These works establish “convincingly” the age of the deposit at the Argyle mine, according to him.

However, other sites related to this geological event did not produce any pink diamonds, he emphasizes. Which suggests that “pink could be an exclusive attribute of Argyle,” concludes.

Source: AFP