According to scientists, the strange diamonds on a dwarf planet in our Solar System may have formed shortly after the dwarf planet collided with a large asteroid about 4.5 billion years ago.
The research team says it has confirmed the existence of lonsdaleite, a rare hexagonal form of diamond, in meteorites from the dwarf planet’s mantle. Lonsdaleite is named after the famous British pioneer woman in the field of crystallography, Dame Kathleen Lonsdale, who was the first woman elected as a Fellow of the Royal Society.
The team found evidence of how lonsdaleite formed in meteorites and published their findings in the Proceedings of the National Academy of Sciences. The study was led by geologist Professor Andy Tomkins from Monash University.
One of the lead researchers involved, Professor Dougal McCulloch from RMIT, said the team predicted that the hexagonal structure of lonsdaleite’s atoms makes it potentially harder than ordinary diamonds, which have a cubic structure.
What is the origin of these mysterious diamonds?
“This study proves unequivocally that lonsdaleite exists in nature,” said McCulloch, director of RMIT, according to EurekAlert. “We also discovered the largest lonsdaleite crystals known to date, which are down to one micron in size – much, much thinner than a human hair.”
The team says the unusual structure of lonsdaleite could help underpin new techniques for making ultra-hard materials in mining applications.
McCulloch and his team at RMIT used advanced electron microscopy techniques to capture solid, intact slices of meteorites to create snapshots of how lonsdaleite and ordinary diamonds formed.
“There is strong evidence that there is a newly discovered formation process for lonsdaleite and common diamond that is like a chemical vapor deposition process that occurred in these space rocks, probably on the dwarf planet shortly after a catastrophic collision.” , McCulloch said.
A newly discovered formation process
“Chemical vapor deposition is one of the ways people produce diamonds in the lab, essentially by growing them in a specialized chamber.”
Tomkins said the team proposed that the lonsdaleite in the meteorites formed from a fluid at high temperatures and moderate pressures, almost perfectly preserving the shape and textures of pre-existing graphite.
“Later, it was partially replaced by diamond as the environment cooled and the pressure dropped,” said Monash University Fellow Tomkins.
“Nature has thus offered us a process to try to replicate in industry. We think it could be used to make tiny, ultra-tough car parts if we can develop an industrial process that promotes the replacement of graphite parts.”
The study was published in Proceedings of the National Academy of Sciences.