Most Expensive Diamonds Reveal the Composition of Earth’s Mantle

We all know that the universe is indefinite and we have not even started uncovering the actual facts about it. Our own planet Earth is still an unsolved mystery to us in many ways. For instance, scientists used to think that most of the materials found deep below the surface of our planet have high oxygen distribution. As it turns out, they were wrong.

kohinoor-diamond

A new study involving the analysis of the most expensive and biggest diamonds of the world has revealed some really interesting facts about Earth’s interior. For those who don’t know, diamonds get formed in the mantle of the Earth, very deep below the crust. Diamonds come up to the surface only during volcanic eruptions.

Now these diamonds have got “inclusions” in them, which are tiny flecks of minerals and metals trapped inside. These inclusions are removed by the jewelers to polish the precious stones before selling them off as jewels. The new study was based on the analysis of these diamond inclusions in order to find out the composition of the Earth’s mantle.

diamond-inclusions
Notice the Diamond Inclusions

Evan Smith and colleagues from the Gemological Institute of America closely observed the scraps left over from cutting and polishing type IIa diamonds. These are those big and expensive variety of diamonds to which popular stones like Constellation, Koh-i-Noor, Cullinan, and Lesedi La Rona belong. The analysis was published in the Science journal a few days back and revealed that the inclusions contain carbon, sulfur, nickel, and iron. These substances are encased in a layer of hydrogen and liquid methane.

Researchers said that the discovery of metallic inclusions suggests that the diamonds were formed under extreme pressure in oxygen-deprived liquid metal patches. Inclusions in some of the larger diamonds suggest that the larger and more expensive stones are formed at a much greater depth than the smaller stones. Most gem diamonds form in the lower part of the continental tectonic plates at 150 to 200 km, while rarer Cullinan-like gems are born in the convecting mantle at depths ranging from 360 to 750 km.

diamond-formation
How Diamonds Are Formed, Courtesy: geology.com

Before conducting the study, researchers used to believe that there’s a uniform mix of oxygen-rick rocks in the Earth’s. However, after studying the large diamonds that are believed to be born in oxygen-deprived patches, the older theory seems to be incorrect. Evan Smith said,”We verify previous predictions that Earth has highly reducing deep mantle regions capable thof precipitating a metallic iron phase that contains dissolved carbon and hydrogen.”

SHARE