March 30, 2023
Professor Andy Tomkins (à esquerda) da Monash University com o acadêmico de doutorado da RMIT University Alan Salek e uma amostra de meteorito analisado -  (crédito: Universidade RMIT/Divulgação)

The diamonds on Earth came from space and can be replicated

Published on 09/13/2022 21:58

Professor Andy Tomkins (left) from Monash University with RMIT PhD scientist Alan Salk and an analyzed meteorite sample – (Credit: RMIT University / Disclosure)

The hardest diamonds found on Earth were formed outside the planet. The extraterrestrial stone, called lonsdaleite, reached Earth in the year meteor That appeared after a small planet collided with a large asteroid in the solar system, about 4.5 billion years ago.

The statement from a group of scientists led by Professor Andy Tomkins – a future ARC fellow in the School of Earth, Atmosphere and Environment at Monash University – who analyzed meteorites that invaded Earth in 2008 filled with stones stronger than diamonds, only that with different geometries – unlike regular diamonds. Lonsdalite features a rare hexagonal design.

Until then, since the discovery of meteorites, scientists believed that diamonds formed with the impact of rocks on the Earth’s atmosphere. However, the group of scientists suspected that the impact would not be enough to create a powerful diamond and began to analyze the state of the stone.

For the analysis, the team used electron microscopy techniques to capture solid and intact slices of meteorites to map diamond formation. Next, the researchers combined data on the average velocity of the asteroids with the chemical process that would occur with the collision from the properties of the two space objects: the planet and the asteroid.

“There is strong evidence that there is a nedalite formation process and that regular diamonds occur from the process of supercritical chemical vapor deposition, which occurred in these space rocks, likely on the dwarf planet shortly after the catastrophic impact,” said Dougal McCulloch. Another senior investigator on the study.

According to the researchers, the process occurs from the interaction between graphite and liquids of the chemical group CHO – carbon, oxygen and hydrogen – enhanced by high temperature.

“Later, Lonsdalite was partially replaced by diamond with the environment being cooler and the pressure lower,” Tomkins said.

Tests were carried out to see if the supposed process was correct in the lab, and through the synthetic process, the researchers obtained the largest lonsdaleite crystals known to date, “much finer than a human hair.”

“This study conclusively proves that Lonsdalite is found in nature, which means it can be produced here on Earth as well,” McCulloch says. Thus, nature has provided us with a process to try to replicate in industry. We believe that lonsdaleite can be used to make extra-rigid machine parts if we can develop an industrial process that promotes the replacement of precast graphite parts with lonsdaleite.”