This planet has huge diamond deposits, study reveals

admin October 07, 2024

A recent study suggests that a thick layer of diamonds could exist hundreds of miles beneath Mercury’s surface, according to a report published in Live ScienceYanhao Lin, a researcher at the Advanced Research Center for High-Pressure Science and Technology in Beijing and a co-author of the study, said Mercury’s extremely high carbon content “made him realize that something special must have happened inside.” The first planet in our solar system does have a magnetic field, but it is much weaker than Earth’s. In addition, NASA’s Messenger spacecraft discovered abnormally black areas on Mercury’s surface that it identified as graphite, a type of carbon.

The results of the study were published in the journal Nature Communications and could shed light on the planet’s composition and unusual magnetic field.

Scientists believe the planet likely formed from the cooling of a hot lava ocean, similar to how other terrestrial planets formed. This ocean was likely rich in silicates and carbon in Mercury’s case. The planet’s outer crust and middle mantle formed from residual magma that crystallized while metals first coagulated inside to form a central core.

For many years, scientists believed that the temperature and pressure in the mantle were just right for carbon to form graphite, which floats to the surface because it is lighter than the mantle. However, a 2019 study found that Mercury’s mantle may be 50 kilometers deeper than previously thought. This would dramatically increase the temperature and pressure at the boundary between the mantle and the core, creating circumstances in which carbon could crystallize into diamond.

To investigate this possibility, a team of Belgian and Chinese researchers prepared chemical soups of carbon, silica and iron. These mixtures, whose composition resembles that of several types of meteorites, would be similar to the magma ocean of young Mercury. In addition, the researchers added different concentrations of iron sulfide to these soups. Based on Mercury’s sulfur-rich surface today, they understood that the magma ocean was also rich in sulfur.

The scientists crushed the chemical mixtures at 7 gigapascals, or 70,000 times the pressure of Earth’s atmosphere at sea level, using a multiple-anvil press. These harsh conditions are similar to those found deep within Mercury. In addition to recreating the physical conditions under which graphite or diamond would be stable, the researchers used computer models to obtain more precise measurements of the temperature and pressure near the boundary between Mercury’s core and mantle. Lin says these computer simulations provide insights into the basic compositions of the planet’s interiors.

Minerals like olivine likely formed in the mantle, the team found. However, the team also found that the chemical mixture only solidified at significantly higher temperatures when sulfur was added. Diamond formation is more likely to occur under such circumstances. Additionally, the team’s computer models suggest that diamonds may have formed during the solidification of Mercury’s inner core under these altered circumstances. They then floated to the core-mantle barrier because they were less dense than the core. If diamonds are present, they are estimated to form a layer that is typically about 15 kilometers thick.

However, it is not possible to extract these diamonds. In addition to the extremely high temperatures on the planet, the diamonds are located nearly 300 miles below the surface, making them impossible to extract. Lin said the diamonds could promote heat transfer between the mantle and the core, leading to temperature differences and swirls of liquid iron, which would produce a magnetic field.