Hundreds of miles below the cinder-scorched surface of Mercury, the Sun’s closest neighbor, may lie riches beyond the wildest dreams of deBeers. Deep down in the planet’s rocky crust may lay a nine-mile thick layer of diamonds.
The new study revealing this tantalizing possibility was published on June 14 in the Nature Communications scientific journal. Should the findings survive replication, they may prove key to the longstanding mystery of Mercury’s peculiar magnetic field, which, although it is much weaker than Earth’s, shouldn’t be there at all according to current models about how planetary magnetism works.
Under the accepted model, magnetic fields are produced by rapid circulation of liquid metallic rock in a planet’s mantle. Mercury, however, is not geologically active, and its tidal lock with the sun means that it does now spin fast enough for scientists to expect magnetism under the current models.
Another of Mercury’s longstanding mysteries are the large graphite (carbon) deposits on its surface, which are unique in the solar system. Yanhao Lin, a scientist working for Beijing’s Center for High Pressure Science and Technology Advanced Research, found his curiosity piqued and decided to study the planet’s interior to see what might explain the graphite deposits.
Previous investigations suggested that Mercury’s mantle might be unexpectedly deep. Lin realized that this would mean the boundary between the crust and the mantle would have unusually high pressure, which could create a planetary diamond factory. Lin and his team of Chinese and Belgian scientists tried to duplicate these conditions using chemical soups of iron, carbon, and silica—a composition similar to that of many meteorites. The researchers then infused the soups with iron sulfide in varying amounts on the assumption that Mercury’s mantle is as sulfur-rich as its surface.
The team then subjected the concoctions to terrific pressures to simulate the deep-Mercury conditions. The result? Diamonds. Using this discovery, Lin and his team have begun building computer models of Mercury’s interior.
