The never-before-seen mineral found inside a diamond


Diamond miners in Botswana were disappointed 30 years ago when they extracted a greenish stone with dark stains inside.

They thought the piece would not have much commercial value and ended up selling it to a mineralogist in the United States, where the diamond has been stored since 1987.

For many years there had been no deeper analysis of the material — until a team of experts finally unraveled something surprising, as shown in a study published last week in the journal Science.

[an error occurred while processing this directive]

The treasure was not the diamond itself, but the internal “smears” that made it imperfect: it contained a mineral never before seen directly by scientists, as its existence only occurs in places of high pressure and temperature, such as the Earth’s mantle. .

But being inside a diamond, he was preserved and saw the light on the surface.

[an error occurred while processing this directive]

The mineral is a type of perovskite —a group of materials that have a well-defined crystal structure—, calcium silicate perovskite (CaSiO3). He was baptized a Davemaoite.

Finding this mineral “tells us a lot about the Earth’s evolution,” geologist Oliver Tschauner, who led the study at the University of Nevada, USA, told the BBC.

an unexpected find

The name Davemaoite is named after the renowned Chinese geologist Ho-Kwang “Dave” Mao of the Center for Advanced Research in High Pressure Science and Technology in Shanghai.

Until now, scientists had only been able to replicate the mineral synthetically in laboratories, as its formation takes place at very high pressure and temperature. Its existence in nature was only theoretical until now.

If the mineral is placed under other conditions of lower pressure, it disintegrates, so scientists thought they would never be able to see it or have a sample.

But because it was embedded in a diamond — which is the product of immense pressures on coal — the material was preserved and researchers were able to observe it using X-ray analysis and mass spectroscopy.

Tschauner notes that the rock probably formed about 660 km below the Earth’s surface, with a pressure 1,000 times greater than that of the atmosphere at the surface.

one second of life

Davemaoite is only a small fraction of what is in the Earth’s lower mantle, “probably only 5% to 7%,” according to experts. But she is a key element.

When it comes into contact with elements such as uranium and thorium, it is part of a radioactive decomposition process that produces the planet’s heat at great depths.

“This decomposition makes up about a quarter to a third of the Earth’s internal heat, so it’s very important,” Tschauner said.

By breaking the diamond that encapsulated it, scientists literally had only a second to analyze the davemaoite, which then turned into a crystal.

However, the data they obtained in the process allow scientists to understand a little more about the planet’s underground composition and processes, as well as the formation of minerals in these environments (and in meteorites).

“For jewelers and diamond buyers, size, color and clarity are important and the existence of inclusions is considered detrimental to quality. But the black blemishes that bother the jeweler were a gift to us,” Tschauner said.


You May Also Like

Recommended for you

Immediate Peak