Science & Tech

Scientists Find Strange Mineral That Formed 170 Kilometers Beneath the Surface

A tiny sample of Goldschmidtite. Image Credit: Nicole Meyer.

It’s not every day that you come across a discovery like this one.

A small fragment of a rock housed inside a diamond contains a mineral never seen before on planet’s surface. The mineral’s chemical signature could explain the reactions that take place in the infernal depths of the earth’s mantle where it was forged, some 170 km beneath the surface, precisely between the crust and the outer core of our planet.

The mineral was discovered by scientists from a volcanic site in South Africa known as the Koffiefontein pipe. Brilliant diamonds speck the dark igneous rock that lines the pipe, and diamonds contain small pieces of other minerals hundreds of miles below the Earth’s surface.

And precisely within one of these bright stones, scientists found an opaque dark green mineral that they estimated was forged about 170 kilometers underground, at the infernal temperature of 1,190 ° C.

The new mineral was dubbed “goldschmidtite” honoring geochemist Victor Moritz Goldschmidt, the godfather of modern geochemistry.

A rare tiny sample of Goldschmidtite. Image Credit: Meyer et al., American Mineralogist, 2019.

A rare tiny sample of Goldschmidtite. Image Credit: Meyer et al., American Mineralogist, 2019.

Extreme pressure

Researchers believe that the entire mantle of the planet has a thickness of just about 2,900 km, which makes the lower regions of the layer difficult for scientists to study.

The intense pressure and heat in the upper mantle transform carbon deposits into brilliant diamonds; The rocks trap other minerals from the mantle in their structures and can be pushed to the surface of the planet by underground volcanic eruptions.

That’s precisely how this little fellow ended up in the hands of the scientists.

By analyzing mineral compositions in diamonds, scientists can take a look at the chemical processes that take place well below the crust. In other words, it offers experts with an unprecedented peek into the reactions that take place hundreds of kilometers beneath the surface of the planet. We can’t go down there, but Earth can send some things up here.

According to the study, published in American Mineralogist, the newly discovered mineral–goldschmidtite–has an extremely peculiar chemical composition.

The scientists revealed that the new mineral has very high concentrations of niobium, potassium, and rare earth elements such as lanthanum and cerium, while the rest of the mantle is dominated by other elements, such as magnesium and iron.

“Potassium and niobium make up the bulk of the mineral, which means that relatively rare elements joined together and concentrated to form the unusual substance, although other nearby elements are more abundant,” explained Nicole Meyer, co-author of the study and Ph.D. student at the University of Alberta in Canada.

The strange mineral is now housed at the Royal Ontario Museum in Toronto, far from where it surfaced and where experts discovered it.

“(The discovery) gives us a snapshot of fluid processes that affect the deep roots of continents during diamond formation,” explained Meyer’s co-supervisor, Graham Pearson, who said there have been several attempts to name new minerals after Goldschmidt, but previous ones have been discredited. “This one is here to stay.”

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