A research team has confirmed the presence of lonsdaleite, a rare hexagonal form of diamond that can be stronger than conventional diamond, in urelite meteorites that arose from the mantle of a distant dwarf planet.
The team consists of scientists from Monash University, RMIT University, CSIRO, Australian Synchotron and Plymouth University and their research was conducted Posted in Proceedings of the National Academy of Sciences (PNAS).
In a press release, RMIT Professor Dougam McCulloch, a member of the team, said the researchers speculated that the hexagonal structure of lonsdaleite atoms could make it more difficult than regular diamond, which has a cubic structure. According to scientists, Lonsdalite may have formed from the collision of the dwarf planet with a large asteroid about 4.5 billion years ago.
“This study conclusively proves that lonsdaleite exists in nature. We also discovered the largest lonsdaleite crystals known to date that are up to a micron in size — much thinner than a human hair,” added McCulloch, who serves as director of the Microscopy and Microanalysis Facility at RMIT.
The research produced strong evidence that Lonsdalite formed from a supercritical chemical vapor deposition process that occurred on the dwarf planet shortly after a “catastrophic collision”. Interestingly enough, this chemical vapor is one of the methods used to make “lab-grown” diamonds.
The team suggests that lonsdaleite formed in meteorites from a supercritical fluid that was present at high temperature and moderate pressure. During operation, it was possible to preserve the original shape and texture of the pre-existing graphite. Later, after the environment cooled and the pressure decreased, lonsdaleite could partly be replaced by conventional diamonds that researchers also discovered in the meteorite.
And so nature has provided us with a process to try and replicate in industry. “We believe lonsdaleite can be used to make extremely tough machine parts if we can develop an industrial process that promotes the replacement of preformed graphite parts by lonsdaleite,” geologist Andy Tomkins, who led the study, said in a statement.
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