A team of scientists discovered lonsdaleite, a rare hexagonal type of diamond that may be stronger than normal diamonds, in ureilite meteorites formed in the mantle of a distant dwarf planet.
The research was published in the Proceedings of the National Academy of Sciences by scientists from Monash University, RMIT University, CSIRO, the Australian Synchrotron, and Plymouth University (PNAS).
In a press release, RMIT Professor Dougam McCulloch, a member of the team, stated that the hexagonal structure of the atoms in lonsdaleite could potentially make it harder than normal diamonds, which have a cubic structure.
Scientists believe the lonsdaleite was produced about 4.5 billion years ago when the dwarf planet collided with a huge asteroid.
“This study establishes unequivocally that lonsdaleite exists in nature.” We also identified the largest lonsdaleite crystals known to date, which are up to a micron in size – much, much thinner than a human hair,” said McCulloch, director of the RMIT Microscopy and Microanalysis Facility.
The study found strong evidence that the lonsdaleite was made by a supercritical chemical vapour deposition process that occurred on the dwarf planet shortly after a “catastrophic collision,” which is also one of the methods used to create “lab-grown” diamonds.
The team hypothesises that lonsdaleite originates in meteorites from a supercritical fluid at high temperature and moderate pressure. The original shape and textures of the pre-existing graphite would have been preserved during the process. Later, as the environment cooled and pressure dropped, the lonsdaleite may have been largely replaced by the typical diamond identified in the meteorite.
“As a result, nature has supplied us with a process that we can strive to imitate in industry.” We believe that lonsdaleite might be utilised to manufacture tiny, ultra-hard machine parts if we can design an industrial procedure that encourages the replacement of pre-shaped graphite components with lonsdaleite,” stated study leader geologist Andy Tomkins in a press release.
