Mercury Has An 11-mile Thick Diamond Layer Between Its Core And Mantle, Report Says

A groundbreaking study by scientists from China and Belgium, recently published in Nature Communications, uncovers the presence of a diamond layer at Mercury’s core-mantle boundary. This remarkable layer is potentially up to 18 kilometers (11 miles) thick and represents a significant advancement in our understanding of planetary differentiation.

The formation of this diamond layer is attributed to the crystallization of Mercury’s carbon-rich magma ocean. As the planet cooled, carbon on its surface formed a graphite crust. However, this new study challenges the long-held belief that graphite was the only stable carbon phase during this cooling period.

Dr. Yanhao Lin, co-author of the study from the Center for High-Pressure Science and Technology Advanced Research in Beijing, remarked, “Many years ago, I noticed that Mercury’s extremely high carbon content might have significant implications. It made me realize that something special probably happened within its interior.”

To uncover these hidden secrets, the researchers conducted high-pressure and temperature experiments, complemented by thermodynamic modeling, to recreate the conditions of Mercury’s interior. They reached pressure levels up to 7 Giga Pascals, allowing them to study the equilibrium phases of Mercury’s minerals in unprecedented detail.

The study found that the presence of sulfur in Mercury’s iron core played a crucial role in the crystallization process of the magma ocean. Sulfur lowers the liquidus temperature, which facilitates the formation of a diamond layer at the core-mantle boundary. Additionally, an iron sulfide layer formed, significantly influencing the carbon content during Mercury’s planetary differentiation.

The high thermal conductivity of this diamond layer profoundly impacts Mercury’s thermal dynamics and magnetic field generation. It helps transfer heat from the core to the mantle, affecting temperature gradients and convection currents in the liquid outer core, which in turn influences the planet’s magnetic field.

These findings not only deepen our understanding of Mercury but also have broader implications for the study of other carbon-rich exoplanetary systems and terrestrial planets with similar sizes and compositions. The processes observed on Mercury could potentially occur on other planets, leaving behind similar signatures. The study suggests that similar diamond layers could exist under the right conditions in other terrestrial planets.