Mercury Might Have 15-Km Layer Of Diamonds: What Are The Chances Of Mining It?

A recent study suggests that there might be a thick layer of diamonds deep beneath the surface of Mercury, the planet that is closest to the Sun. This finding, reported by Live Science, could explain Mercury's unusual features and weak magnetic field. The research, led by Yanhao Lin from the Center for High-Pressure Science and Technology Advanced Research in Beijing, was published in the journal Nature Communications.

Lin and his team were curious about Mercury's high carbon content and weak magnetic field. They also noted strange dark spots on the planet's surface, which NASA's Messenger spacecraft identified as graphite.

Scientists believe Mercury formed like other rocky planets, starting as an ocean of hot lava. As it cooled, silicate and carbon likely crystallised to form the mantle and crust, while metals formed the core.

Earlier theories suggested that the mantle's temperature and pressure could turn carbon into graphite, which would rise to the surface. However, a 2019 study found that Mercury's mantle might be deeper than previously thought, creating conditions for diamonds to form instead of graphite.

Lin's team, including scientists from China and Belgium, tested this idea by mixing carbon, silica, and iron, imitating the composition of certain meteorites and Mercury's early magma. They added iron sulfide to match Mercury's sulfur-rich surface.

Using a high-pressure press, the researchers replicated the extreme conditions inside Mercury, with pressures of 7 gigapascals and temperatures up to 1,970 degrees Celsius. They also used computer models to determine if graphite or diamond would form under these conditions.

The results showed that minerals like olivine probably formed in the mantle. However, sulfur raised the temperature at which the mixtures solidified, leading to diamond formation.

The computer models suggested that as Mercury's inner core solidified, diamonds might have crystallised and moved to the core-mantle boundary, forming a layer about 15 km thick.

While the idea of a diamond layer is exciting, mining these diamonds is impractical. They are 485 km below Mercury's surface, and the planet's extreme heat makes them unreachable. However, Lin speculates that these diamonds might influence Mercury's magnetic field by helping transfer heat between the core and mantle, causing temperature differences that generate the magnetic field.

This study also impacts our understanding of carbon-rich exoplanets. Lin suggests that similar processes could have created diamond layers on other planets, even before they occurred on Mercury.

More information might come from the BepiColombo mission, a joint project between the European Space Agency and Japan Aerospace Exploration Agency. Launched in 2018, the spacecraft is set to start orbiting Mercury in 2025, potentially revealing more about the planet's mysterious interior.