A new study published in Nature Communications suggests that Mercury may have a layer as thick as 18 km of diamonds at the boundary between the core and the mantle (although the uncertainty is quite significant: about 10 km). The results of the study, which used complex computer simulations, were conducted by researchers from China and Belgium coordinated by the Belgian universities of Liège and Louvain.
Diamonds actually appear to be quite common in the Solar System: their presence has already been hypothesized on the ice giants Uranus and Neptune, and even on Mercury – the smallest planet in the Solar System – the discovery does not come so unexpectedly, since vast quantities of diamonds are visible on its surface. graphite depositswhich like diamonds is made of pure carbon.
But put your pickaxes aside: even if we had the technology to mine diamonds on other planets – and we don’t at the moment – these diamonds are found at a depth of well over 485 km beneath the scorching surface of the planet closest to the Sun.
The Motivations for the Study: Mercury’s Unsolved Mysteries
The recent study on Nature Communications It arises from the attempt of researchers to explain some of the mysteries still unsolved of Mercury. The planet in fact has a magnetic field which, although weak, is still unexpected since it is geologically inactive.
Another mystery lies in the presence on its surface of dark spots that the mission researchers Messenger of NASA (in orbit around Mercury since 2011) have discovered that it is graphite depositsa form of carbon which, for example, the tips of pencils are made of.
These graphite patches were the spark that gave rise to the study in question. However, no one had hypothesized that carbon could also transform into diamond, because the known information on Mercury did not foresee, either on the surface or underground, the conditions of temperature and pressure suitable for forming diamonds.
Where Diamonds Are Found on Mercury
In the 2019 However, the scenario has changed since researchers discovered that Mercury’s mantle is actually 80 km deeper than previously thought. This would create the right pressure and temperature conditions for diamonds to form.
But a theory remains speculation until it is tested experimentally. For this reason, the scientists who wrote the article on Nature Communications they have recreated in the laboratory a blend that it had the same hypothesized chemical composition as the part of the mantle where diamonds are thought to form.
This blend is made of iron, silicon, carbon and iron sulfidean ingredient added to the mixture because of the large amount of sulfur present on Mercury’s surface. Sulfur also helps to increase the temperature at which the chemical mixture solidifies.
The scientists then applied the mixture to the same temperature and pressure conditions of the interior of Mercury. We are talking about a temperature of well 3578 °C and of a pressure 70000 times greater than that on Earth at sea level. These values were obtained, clearly, not by measuring them directly on Mercury, but through computer models which also simulate the physical conditions under which graphite or diamond would be stable.
The result was astonishing. By combining laboratory data with computer simulations, scientists concluded that diamonds could have crystallized when Mercury’s inner core solidified. However, because they are less dense than the core, they floated to the surface. boundary between the core and the mantleforming one layer of 15-18 km of diamonds.
Diamonds May Explain Mercury’s Magnetic Field
The presence of diamonds has an importance that goes beyond the mere material value. Diamonds could in fact explain the presence of the weak magnetic field of Mercury. The idea is that diamonds would help heat exchange between the mantle and the core, creating temperature differences that would cause the liquid iron in the core to rotate. Being conductive, this would then create a magnetic field.
