Scientists from Monash University, RMIT University, CSIRO, the Australian Synchrotron, and Plymouth University recently confirmed the presence of lonsdaleite—a rare hexagonal form of diamond that may be stronger than conventional diamonds—in ureilite meteorites formed in the mantle of a distant dwarf planet.
About The Strange Diamonds
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 regular diamonds, which have a cubic structure. According to him, the lonsdaleite may have formed as a result of the dwarf planet colliding with a large asteroid about 4.5 billion years ago.
“This study proves categorically that lonsdaleite exists in nature. We have also discovered the largest lonsdaleite crystals known to date that are up to a micron in size – much, much thinner than a human hair,” added McCulloch, who serves as the director of the RMIT Microscopy and Microanalysis Facility.
The study found strong evidence that the lonsdaleite was formed 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 formed 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 partially replaced by the conventional diamond discovered in the meteorite.
“Nature has thus provided us with a process to try and replicate in industry. We think that lonsdaleite could be used to make tiny, ultra-hard machine parts if we can develop an industrial process that promotes the replacement of pre-shaped graphite parts by lonsdaleite,” said geologist Andy Tomkins, who led the study, in a press statement.
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