Dwarf Planet Collision 4.5M Years Ago May Have Sent These Unusual Diamonds To Earth [Photo]

Unique hard diamonds may have fallen to Earth after a dwarf planet collided with an asteroid around 4.5 million years ago.

The unusual diamonds, called lonsdaleite, were recovered from a rare class of meteorites called ureilite, researchers said in a paper published in the journal Proceedings of the National Academy of Sciences on Monday.

"This study proves categorically that lonsdaleite exists in nature," co-author Dougal McCulloch, a microscopist at RMIT University in Australia, said in a statement. "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."

Understanding the process behind lonsdaleite formation could help in manufacturing ultra-hard materials used in the mining industry.

Lonsdaleite is hexagonal in shape, unlike the cubic structure of normal diamonds, and it is named after British crystallographer Dame Kathleen Lonsdale. It was first discovered in the Canyon Diablo meteorite in 1967. Lonsdaleite is predicted to be harder than normal diamonds due to its hexagonal structure, according to senior author Dougal McCulloch, a professor at RMIT University.

Ureilite meteorites are believed to have come from a destroyed inner solar system dwarf planet and typically contain more diamonds than any known rock.

Explaining the process of lonsdaleite formation, McCulloch said, "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."

"Chemical vapor deposition is one of the ways that people make diamonds in the lab, essentially by growing them in a specialized chamber," the professor added.

The team concluded that lonsdaleite was formed in the meteorite from a supercritical fluid at high temperatures under moderate pressures. These conditions allowed lonsdaleite to preserve the shape and textures of the pre-existing graphite.

"Later, lonsdaleite was partially replaced by diamond as the environment cooled and the pressure decreased," Andrew Tomkins, from Monash University's School of Earth, Atmosphere and Environment, said.

"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 the replacement of pre-shaped graphite parts by lonsdaleite," the researcher explained.