Around 4.5 billion years ago, an asteroid likely collided with a dwarf planet spewing meteorites into space including some that contain a strange kind of diamond. Called lonsdaleite, these space diamonds has a hexagonal structure rather than the cubic structure of a typical diamond. Researchers form Australia's Monash University, RMIT University, and colleagues just confirmed the existence of the space diamonds in a meteorite and determined the natural process by which it formed. From RMIT University/EurekAlert!:
"This study proves categorically that lonsdaleite exists in nature," said McCulloch, Director of the RMIT Microscopy and Microanalysis Facility.
"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."
The team says the unusual structure of lonsdaleite could help inform new manufacturing techniques for ultra-hard materials in mining applications.
McCulloch and his RMIT team, PhD scholar Alan Salek and Dr Matthew Field, used advanced electron microscopy techniques to capture solid and intact slices from the meteorites to create snapshots of how lonsdaleite and regular diamonds formed.
"There's strong evidence that there's a newly discovered formation process for the lonsdaleite and regular diamond, which is like a supercritical chemical vapour deposition process that has taken place in these space rocks, probably in the dwarf planet shortly after a catastrophic collision," McCulloch said.
"Chemical vapour deposition is one of the ways that people make diamonds in the lab, essentially by growing them in a specialised chamber."