Mysterious, ultra-strong diamonds on Earth came from outer space

A study on the diamonds titled "Sequential Lonsdaleite to Diamond Formation in Ureilite Meteorites via Chemical Fluid/Vapor Deposition" has been published in the journal Proceedings of the National Academy of Sciences.

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Australian researchers have confirmed the presence of a rare type of diamond called lonsdaleite in ureilite meteorites from the mantle of a dwarf planet that was destroyed in our inner solar system. The dwarf planet is thought to have collided with a large asteroid roughly 4.5 billion years ago, creating localized high temperatures and pressures that led to the creation of the diamonds.

These diamonds are also found in ureilite on Earth, suggesting the diamonds may have found their way to Earth from this dwarf planet. Lonsdaleite, named after crystallographer Dame Kathleen Lonsdale, has a hexagonal structure to its atoms that theoretically allows it to be up to 58% harder than regular diamonds, which have a cubic structure. This makes it potentially extremely useful for manufacturing other ultra-hard materials, such as those used in mining applications.

"There's strong evidence that there's a newly discovered formation process for the lonsdaleite and regular diamond, which is like a supercritical chemical vapor deposition process that has taken place in these space rocks, probably in the dwarf planet shortly after a catastrophic collision," said RMIT Professor Dougal McCulloch.

The researchers believe that as the environment cooled and the pressure decreased on the dwarf planet following asteroid impact, lonsdaleite formation was steadily replaced by regular diamond formation.

"Nature has thus provided us with a process to try and replicate in industry. 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," said geologist Professor Andy Tomkins from Monash University.

You can read more from the study here.