An international research team has uncovered the mysterious source of a diamond from outer space known as lonsdaleite, an extremely rare hexagonal shape of diamond.
Scientists have confirmed the presence of lonsdaleite in urilite meteorites from the mantle of an ancient dwarf planet in our solar system. The team believes that space diamonds formed shortly after the collision of the dwarf planet A . giant asteroid About 4.5 billion years ago.
The investigation published in Proceedings of the National Academy of Sciences (PNAS)which includes researchers from Monash University, RMIT University, CSIRO, Australian Synchrotron and the University of Plymouth.
Where does Lonsdalite come from?
Lonsdaleite is named after Dame Kathleen Lonsdale, a famous British crystallologist who was the first woman ever to be elected as a Fellow of the Royal Society.
In their study, the team used advanced electron microscopy techniques to obtain solid, intact slices of meteorites to develop snapshots of how ordinary diamonds and diamonds formed.
RMIT Professor Dougal McCulloch, one of the lead researchers on the project, commented: “There is strong evidence for a newly discovered formation process for lonsdaleite and ordinary diamond, which is similar to the process of supercritical chemical vapor deposition that occurred in this space of rock, possibly on a dwarf planet some time later. Short of a catastrophic collision, chemical vapor deposition is one way people make diamonds in the lab, primarily by growing them in a specialized room.
“This study conclusively proves that Lonsdalite exists in nature. We have also discovered the largest Lonsdalite crystals known to date which are up to a micron in size – much thinner than a human hair.”
The researchers hypothesized that the lonsdaleite in meteorites formed from a supercritical fluid at high temperature and moderate pressure, which preserves the shape and texture of pre-existing graphite almost perfectly.
Professor Andy Tomkins, research leader and geoscientist at Monash University, said: “Later, Lonsdalite was partially replaced by diamond as the environment cooled and the pressure was lower. And so nature provided us with a process to try and replicate in industry.”
Potential uses of space diamonds
The team explained that the hexagonal structure of Lonsdalite atoms makes it harder than regular diamond, which has a cubic structure. As a result, its robust structure may make it useful for new fabrication techniques for ultra-hard materials in mining applications.
Professor Tomkins concluded: “We believe that lonsdaleite can be used to make micro-machine parts if we can develop an industrial process that promotes the replacement of preformed graphite parts with lonsdaleite.”