Tiny folded diamonds that fell to Earth from an ancient dwarf star may look like something out of an intergalactic feature film, but researchers in Australia and the UK have proven the existence of these rare gems after examining a stony meteorite.
Australian and British scientists have established the existence of lonsdaleite, a rare hexagonal species diamondno larger than a human hair, which the researchers note is layered in a distinctive folded pattern, unlike earth-formed diamonds which have a cubic structure.
The existence of Lonsdaleite – named after the pioneering British crystallographer Dame Kathleen Lonsdale – was once debated because its very existence could not be proven.
The research team’s lead scientist, Professor Andy Tomkins, from the School of Earth, Atmosphere and Environment at Monash University, said the mysteries of the rare diamond prompted him to continue his research on ureilite meteorites in his laboratory.
Tomkins said it was a case of curiosity-driven science.
“It’s exactly the kind of sighting that piques curiosity that sends scientists diving down rabbit holes for months,” he said.
Naturally formed ureilite meteorites contain a greater abundance of diamonds than any known rock on Earth. It is also one of the few opportunities to study the mantle layer of dwarf planets.
The samples are created when asteroids collide with a planet while they are still hot, creating the ideal conditions for lonsdaleite and diamond growth due to moderate pressure and rapid temperature drops in the environment rich in fluids and gases.
“These findings help solve a long-standing mystery regarding the formation of carbon phases in ureilites that has been the subject of much speculation,” Tomkins said.
Tomkins has also collaborated with researchers from CSIRO, RMIT University, Australia’s Synchrotron and the University of Plymouth to uncover samples of lonsdaleite in nature, providing insight into the potential replication of the process for industrial purposes.
“These diamonds are quite special,” said Alan Salek, physicist and RMIT PhD researcher.
“Normal diamonds that you would find here on Earth, like on an engagement ring, have a specific atomic structure that is cubic. These special diamonds have a hexagonal structure.
“It’s quite exciting because it’s a new form of material.”
The unique shape is believed to explain why lonsdaleite is stronger than any other diamond.
Important Implications for Mining and Manufacturing
Colin MacRae, CSIRO scientist, in a Press releasesaid the discovery has huge potential for industries like mining.
“If something that’s harder than diamond can be made easily, that’s something the industry would want to know,” MacRae said.
Macrae noted that the discovery meant they could find a way to replicate the mineral.
“Lonsdaleite could be used to make tiny, ultra-hard machine parts if we could develop an industrial process that promotes the replacement of preformed graphite parts with lonsdaleite,” he said.
Currently, the current process for producing industrial diamonds involves chemical vapor deposition, in which diamonds are formed on a substrate from a low pressure gas mixture.
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