A miles-thick layer of diamonds might be lurking beneath this planet’s surface

The planet closest to the Sun possesses characteristics not seen in other planets of our solar system. This includes the end of its volcanic era, dense core, very dark surface and patches of graphite. Scientists believe these patches could be remains of an erstwhile carbon-rich magma ocean. Apart from giving its surface a dark hue, this ocean could also have possibly contributed in the formation of a carbon-rich mantle beneath the surface.

“We calculate that, given the new estimate of the pressure at the mantle-core boundary, and knowing that Mercury is a carbon-rich planet, the carbon-bearing mineral that would form at the interface between mantle and core is diamond and not graphite,” team member Olivier Namur, an associate professor at KU Leuven, told Space.com.

The diamonds, Namur explained, could have been formed by two processes: first, the crystallisation of the magma ocean that contributed to the formation of a very thin layer of diamonds; and second, the crystallisation of the metal core of Mercury.

Pressure and temperature at the boundary between the core and the mantle likely created conditions where the carbon could crystallise into diamond, with the layer increasing in thickness over time, according to Live Science.

Mining these gems is not feasible, owing to the planet’s extreme temperatures and the depth of almost 485 kilometres below the surface where the layer sits. However, they could offer an understanding of the small planet’s magnetic field, apart from explaining how carbon-rich exoplanets evolve.

BepiColombo, a joint mission of the European Space Agency and the Japan Aerospace Exploration Agency, is scheduled to begin orbiting Mercury in 2025. It may offer a deeper look into the mysteries of the planet.

Meanwhile, NASA’s MESSENGER (Mercury Surface, Space Environment, Geochemistry, and Ranging) was launched in August 2004 and became the first spacecraft to orbit Mercury. The mission, which ended in 2015, mapped the planet, discovering abundant water ice at the poles and gathering crucial data about geology and magnetic field.