Discover the Astonishing Chemistry Behind South Africa’s Mysterious Diamonds

Two fascinating diamond samples were discovered in a South African mine, and they tell us a great deal about what happens deep within the Earth. These diamonds, formed hundreds of kilometers below the surface, contain tiny pieces of different materials that usually don’t mix. This unusual combination raises exciting questions about the chemistry of our planet’s mantle.

When diamonds form, they often trap small bits of surrounding rocks in a process called inclusions. While jewelers usually prefer diamonds without these flaws, for scientists, they are treasure troves of information. These particular inclusions originate from deep within the Earth where conditions are extreme. Unlike most diamond inclusions, which typically show similar chemical properties, these two samples feature both oxidized (oxygen-rich) and reduced (oxygen-poor) materials. This rare duality puzzled researchers, including Yaakov Weiss, a senior lecturer in Earth sciences at the Hebrew University of Jerusalem. The findings were so unusual that they initially set the samples aside for a year for further study.

Upon reanalysis, the scientists realized that these inclusions provide a snapshot of a chemical reaction that leads to diamond formation. This is the first time we’ve seen such a reaction captured in natural diamonds. According to Weiss, it represents two extremes of the oxidation spectrum.

Understanding these diamonds is vital. As we move deeper into the Earth, rocks generally become more reduced, meaning they have fewer oxygen molecules. However, there’s been limited direct evidence of this shift. Maya Kopylova, a professor of Earth sciences at the University of British Columbia, notes that most research has focused on depths up to 200 kilometers. The new diamond samples, which originated from depths of 280 to 470 kilometers, challenge previous assumptions. They suggest that oxidized materials can exist much deeper in the mantle than previously thought.

Interestingly, these findings have implications for the kimberlite rocks that bring diamonds to the surface. Previously, researchers believed these rocks couldn’t originate from below 300 kilometers due to their oxidized nature. Now, this new evidence implies that kimberlite could come from even greater depths.

The formation of diamonds likely occurs when carbonate fluids carried by subducting tectonic plates interact with metallic compounds in the mantle. This process is similar to sugar crystallizing from syrup as it cools. However, scientists haven’t ruled out other pathways for diamond formation.

Moreover, these nickel-rich inclusions could shed light on an odd phenomenon seen in some diamonds: nickel atoms replacing carbon in the diamond structure. Kopylova wonders if understanding this could illuminate how diamonds form at various depths.

In summary, these two diamond samples open new doors in our understanding of deep Earth chemistry, helping to explain processes that have remained a mystery for decades. They remind us how much we still have to learn about our planet’s hidden depths.



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