Scientists believe they have figured out why a rare form of diamond is found inside meteorites. The origin story of the crystal is as shocking as the material itself.
Lonsdaleite may have formed in the chaos of a catastrophic collision in interplanetary space, unlike traditional diamonds, which are formed slowly by the pressures deep within Earth's mantle.
The whole diamond structure is robust enough to make it one of the hardest substances on Earth.
The structure of lincolnite preserves the hexagonal shape of graphite.
The material should be even more stiff because of the structure. It's hard to prove that hypothesis.
The only samples that have been collected so far are very thin and difficult to analyze in the lab.
The strange material was first identified in a meteorite in 1967. A group of researchers argued that lonsdaleite was not a naturally occurring material but a diamond that was in a state of disorder.
The hypothesis didn't stand up to scrutiny in the years since.
Lonsdaleite has mostly been found in a rare type of stony meteorite called a ureilite, but it has also been made in the lab under high temperatures, and found in places thought to have been hit by asteroids.
Small pieces of space debris are believed to have come from a long obliterated dwarf planet.
It supports a collision origin theory for lonsdaleite.
An international team of researchers used advanced electron microscope techniques on 18 ureilite samples to study the formation of lonsdaleite.
The authors say they have proven that lonsdaleite can be formed in a way that is similar to how scientists make it in the lab.
"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."
Growing diamonds in a specialized chamber is one of the ways that chemical vapor deposition can be used.
Previous research has found signatures in diamond filled meteorites that are consistent with low-pressure CVD processes.
The paper suggests that lonsdaleite is formed in a mildly pressurized environment of an impact between a sufficientlysized mass and a dwarf planet, not in the highly pressurized mantle of a larger planet.
The majority of the meteorite samples analyzed had small diamonds in them. The diamond-rich sections were neighbors to the diamond-less patches.
According to the researchers, if the right composition of mineral is given a big enough shock, hot gas and fluid could theoretically be dispersed along the grain boundaries. Sub grains of super-hard material could be formed as the rock cools.
Andy Tomkins says that nature has provided them with a process to try and replicate.
If we can develop an industrial process that promotes replacement of pre-shaped graphite parts by lonsdaleite, we think that it would be possible to make tiny, ultra-hard machine parts.
It could be used for an engagement ring.
The study was published in a peer reviewed journal.
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