Tiny folded diamonds that fell to Earth from an ancient dwarf star may sound like something from an intergalactic feature film, but researchers from Australia and the United Kingdom have proven the existence of the rare gems after examining a stony meteorite.
Scientists from Australia and the UK have established the existence of lonsdaleite, a rare hexagonal diamond, no bigger than a human hair, that researchers note is layered into a distinctive folded pattern, unlike the earth-formed diamonds that have a cubic structure.
The existence of Lonsdaleite—named after the pioneering British crystallographer Dame Kathleen Lonsdale—has previously been the subject of debate because its very existence could not be proven.
The lead scientist on the research team Prof. Andy Tomkins, from Monash University’s School of Earth, Atmosphere, and Environment, said the mysteries of the rare diamond were what drove him continue researching ureilite meteorites in his lab.
Tomkins said it was a case of curiosity-driven science.
“This is exactly the sort of curiosity-piquing observation that sends scientists diving down rabbit holes for months on end,” he said.
Scientists from Australia and the UK have established the existence of lonsdaleite, a rare hexagonal diamond no bigger than human hair. Image shows the ‘The Rock,’ a 228.31-karat pear-shaped white diamond, in Geneva on May 6, 2022. (Fabrice Coffrini/AFP via Getty Images)
Naturally formed ureilite meteorites contains a higher abundance of diamond than any known rock on Earth. They are 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 still hot, creating the ideal conditions for lonsdaleite and diamond growth due to moderate pressure and rapid temperature drops in the fluid and gas-rich environment.
“These findings help address a long-standing mystery regarding the formation of the carbon phases in ureilites that has been the subject of much speculation,” Tomkins said.
Tomkins also collaborated with researchers from the CSIRO, RMIT University, the Australian Synchrotron, and Plymouth University to discover samples of lonsdaleite in nature, offering an insight into 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’s cubic. These special diamonds are hexagonal in structure.”
“It’s pretty exciting because it’s a new form of material.”
The unique shape is believed to be why lonsdaleite is stronger than any other diamond.
Significant Implications For Mining and Manufacturing
CSIRO scientist Colin MacRae in a media release, said the discovery has enormous potential for industries like mining.
“If something that’s harder than diamond can be manufactured readily, that’s something industry would want to know about,” MacRae said.
Macrae noted that the discovery meant they could find a way to reproduce the mineral.
“Lonsdaleite could be used to make tiny, ultra-hard machine parts if we can develop an industrial process that promotes the replacement of pre-shaped graphite parts by lonsdaleite,” he said.
At present, the current method for producing industrial diamonds involves chemical vapour deposition, in which diamonds are formed onto a substrate from a gas mix at low pressures.