Rare cosmic gem created by ancient "catastrophic collision," scientists say




  • In Science
  • 2022-09-13 13:00:00Z
  • By CBS News

Scientists have discovered that an ancient "catastrophic collision" between a dwarf planet and an asteroid is responsible for the creation of a rare and mysterious cosmic gem.

The findings, published in the Proceedings of the National Academy of Sciences, unveiled that a 4.5 billion-year-old collision created lonsdaleite, a crystal that could potentially be harder than regular diamonds. Its crystal structure is hexagonal, which explains why lonsdaleite is also called a "hexagonal diamond."

Their discovery came from finding the gem in ureilite meteorites, which according to Space.com, are a "rare class of space rocks" that scientists believe contain material from the mantle of dwarf plants.

Monash University Professor Andy Tomkins (left) with RMIT University PhD scholar Alan Salek holding a ureilite meteor sample at the RMIT Microscopy and Microanalysis Facility.
Monash University Professor Andy Tomkins (left) with RMIT University PhD scholar Alan Salek holding a ureilite meteor sample at the RMIT Microscopy and Microanalysis Facility.  

Scientists used advanced electron microscopy to analyze the meteorites and create snapshots of lonsdaleite and diamond formation.

Dougal McCulloch, director of the royal Melbourne Institute of Technology Microscopy and Microanalysis Facility, said that he and his team found "strong evidence" that the crystal was formed in a newly-discovered process.

It's like a "supercritical chemical vapour deposition process," he said, a process that is also a way people make lab-grown diamonds. It's likely that the process took place within space rocks and "probably in the dwarf planet shortly after a catastrophic collision," he said.

They predict that the lonsdaleite was somewhat replaced by diamonds as its environment cooled and pressure decreased, scientists said.

And they didn't just find the source of the mysterious crystal.

"This study proves categorically that lonsdaleite exists in nature," McCulloch said. "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."

All of this could help pave the way for advancement in industrial processes, the team said.

"Nature has thus provided us with a process to try and replicate in industry," Monash University geologist and professor Andy Tomkins said. "We think that lonsdaleite could be used to make tiny, ultra-hard machine parts if we can develop an industrial process that promotes replacement of pre-shaped graphite parts by lonsdaleite."

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