posted on 09/13/2022 21:58
Professor Andy Tomkins (left) of Monash University with RMIT University doctoral scholar Alan Salek and an analyzed meteorite sample – (Credit: RMIT University/Disclosure)
The hardest type diamond ever found on Earth was formed outside the planet. The extraterrestrial stone, named lonsdaleite, arrived on Earth in a meteorite that emerged after a small planet collided with a large asteroid in the Solar System, about 4.5 billion years ago.
The statement is from a group of scientists led by Professor Andy Tomkins — ARC Future Fellow of the School of Earth, Atmosphere and Environment at Monash University — who analyzed meteorites that invaded Earth in 2008 filled with stones harder than diamond, only that with a different geometric shape — unlike regular diamond, lonsdaleite has a rare hexagonal design.
Until then, since the discovery of meteorites, scientists thought that the diamond formed with the impact of the rock with the Earth’s atmosphere. The group of scientists, however, suspected that the impact would not be enough to create a powerful diamond and began to analyze the condition of the stone.
For the analysis, the team used electron microscopy techniques to capture solid, intact slices of the meteorites to map the formation of the diamond. Next, the researchers pieced together the average velocity data of asteroids with the chemical process that would occur with the collision from the characteristics of each of the two space objects: the planet and the asteroid.
“There is strong evidence that there is a formation process for lonsdaleite and regular diamond occurs from the process of supercritical chemical vapor deposition, which occurred in these space rocks, probably on the dwarf planet shortly after a catastrophic collision,” said Dougal McCulloch. , another senior investigator on the study.
According to the researchers, the process occurs from the reaction between graphite and fluids of the chemical group CHO — carbon, oxygen and hydrogen — promoted by a high temperature.
“Later, lonsdaleite was partially replaced by diamond as the environment cooled and the pressure decreased,” Tomkins said.
The tests to see if the supposed process was correct took place in the laboratory and, with the artificial process, the researchers obtained the largest lonsdaleite crystals known to date, “much finer than a human hair”.
“This study categorically proves that lonsdaleite exists in nature, meaning it can be produced here on earth as well,” says McCulloch. “Nature has thus provided us with a process to try to replicate in the industry. We think lonsdaleite could be used to make tiny, ultra-hard machine parts if we can develop an industrial process that promotes the replacement of precast graphite parts with lonsdaleite,” he added.