Scientists have discovered something about our planet that they previously believed was nearly impossible thanks to two tiny natural diamonds. The De Beers Group donated these gems, which were discovered in the Voorspoed mine in South Africa.
For months, they were kept in a drawer because researchers knew they were unique but did not know why. They are now “time capsules” from deep within the Earth that provide insights into the Earth’s mantle, the enormous layer beneath the crust where the majority of diamonds are formed, thanks to meticulous research. From hundreds of kilometers below our feet, they resemble sealed messages rather than merely being lovely stones.
A group of scientists, supervised by Yaakov Weiss of the Hebrew University of Jerusalem, have discovered new information about the chemistry of the Earth’s interior and how various forms of matter can coexist in harsh environments by looking inside them.
What the diamonds revealed
The study published in Nature, shows that between 280 and 470 kilometers deep in the Earth’s mantle, these two natural diamonds were formed. Tiny inclusions—minuscule fragments of metals, minerals, and liquids that were trapped when the diamonds grew—were discovered inside of them by scientists. These inclusions are seen as flaws in jewelry, but they are evidence in science.
The important result is related to redox reactions, which are chemical processes in which atoms gain or lose electrons. For a long time, scientists believed that certain redox states in the deep Earth couldn’t exist together. These diamonds show that they can. Their inclusions demonstrate evidence of deep oxygen in oxidized fluids and the presence of reduced materials (like some metals) and oxidized materials (like carbonates) next to each other.
This suggests the deep mantle is not uniform. Instead, it consists of tiny “micro-environments” with unique chemical properties. Until recently, it was almost impossible for such opposites to coexist, but the team found that these stones did just that, according to Yaakov Weiss.
Why this changes how we see Earth’s interior
Scientists’ perspectives on the chemistry of the Earth’s interior are impacted by this discovery. Previously, a lot of theories thought that the deep mantle behaved chemically in a fairly uniform manner. It is now evident that it is more complex because of these natural diamonds: patches with deep oxygen and varying redox conditions can coexist.
Which minerals are stable, how carbon is stored (as graphite, diamond, carbonate, or other forms), and how magmas form and migrate are all influenced by redox conditions. The results could also help explaining the origin of some volcanic systems, like those associated with kimberlite rocks, which are unique volcanic rocks that have the ability to raise diamonds from the Earth’s mantle to the surface.
The two diamonds from the Voorspoed mine in South Africa captured the chemical processes that transformed material from the deep mantle into crystal. Their features kept mostly intact when they climbed, giving scientists a unique and close-up view of processes that are normally inaccessible.
What comes next for science
This is only the beginning for the researchers. New opportunities for geological research are made possible by the work built from these two diamonds. Scientists hope to get a better understanding of how redox reactions and carbon-rich fluids shape the Earth’s mantle, impact volcanic activity, and produce chemical differences deep beneath us by studying more inclusions in more natural diamonds. According to Yaakov Weiss and his colleagues, these findings contribute to the understanding of the “evolution and chemical heterogeneity” of the interior of our planet.
Two diamonds that once seemed to be scientific mysteries are now helping us see our planet more clearly, thanks to the De Beers Group’s donation, meticulous work at the Hebrew University of Jerusalem, and thorough geological research.