Lonsdaleite, also referred to as hexagonal diamond in reference to the crystal structure, is an allotrope of carbon with a hexagonal lattice, instead of the cubical lattice of standard diamond. It was named in honor of Kathleen Lonsdale, a crystallographer.
RMIT Professor Dougal McCulloch, one of the senior scientists involved, said the team forecasted the hexagonal structure of lonsdaleites atoms made it potentially harder than routine diamonds, which had a cubic structure.
” This research study shows unconditionally that lonsdaleite exists in nature,” stated McCulloch, Director of the RMIT Microscopy and Microanalysis Facility.
” We have actually likewise discovered the largest lonsdaleite crystals known to date that are up to a micron in size– much, much thinner than a human hair.”
According to the research group, the uncommon structure of lonsdaleite could help inform new production methods for ultra-hard products in mining applications.
Whats the origin of these mysterious diamonds?
McCulloch and his RMIT group, PhD scholar Alan Salek and Dr. Matthew Field, used advanced electron microscopy techniques to catch undamaged and solid pieces from the meteorites to create photos of how lonsdaleite and regular diamonds formed.
” Theres strong proof that theres a freshly found formation procedure for the lonsdaleite and regular diamond, which is like a supercritical chemical vapor deposition procedure that has taken place in these area rocks, most likely in the dwarf planet shortly after a devastating accident,” McCulloch said.
” Chemical vapor deposition is among the methods that people make diamonds in the laboratory, essentially by growing them in a specialized chamber.”
Professor Dougal McCulloch (left) and PhD scholar Alan Salek from RMIT with Professor Andy Tomkins from Monash University (ideal) at the RMIT Microscopy and Microanalysis Facility. Credit: RMIT University
Tomkins stated the group proposed that lonsdaleite in the meteorites formed from a supercritical fluid at high temperature and moderate pressures, nearly perfectly preserving the shape and textures of the pre-existing graphite.
” Later, lonsdaleite was partially replaced by diamond as the environment cooled and the pressure reduced,” said Tomkins, an ARC Future Fellow at Monash Universitys School of Earth, Atmosphere and Environment.
” Nature has actually hence offered us with a process to duplicate and try in industry. We think that lonsdaleite could be utilized to make small, ultra-hard maker parts if we can develop a commercial process that promotes replacement of pre-shaped graphite parts by lonsdaleite.”
Tomkins stated the study findings assisted deal with an enduring secret regarding the formation of the carbon phases in ureilites.
The power of cooperation
CSIROs Dr. Nick Wilson stated the collaboration of innovation and expertise from the numerous institutions involved enabled the team to confirm the lonsdaleite with self-confidence.
At CSIRO, an electron probe microanalyzer was utilized to quickly map the relative circulation of graphite, diamond, and lonsdaleite in the samples.
” Individually, each of these methods gives us a great concept of what this product is, but taken together– thats really the gold standard,” he said.
Reference: “Sequential Lonsdaleite to Diamond Formation in Ureilite Meteorites by means of In Situ Chemical Fluid/Vapor Deposition” by Andrew G. Tomkins, Nicholas C. Wilson, Colin MacRae, Alan Salek, Matthew R. Field, Helen E. A. Brand, Andrew D. Langendam, Natasha R. Stephen, Aaron Torpy, Zsanett Pintér, Lauren A. Jennings and Dougal G. McCulloch, 12 September 2022, Proceedings of the National Academy of Sciences.DOI: 10.1073/ pnas.2208814119.
The research group– with researchers from Monash University, RMIT University, CSIRO, the Australian Synchrotron, and Plymouth University– discovered proof of how lonsdaleite formed in ureilite meteorites. They released their findings on September 12 in the Proceedings of the National Academy of Sciences (PNAS). Geologist Professor Andy Tomkins from Monash University led the study.
Professor Andy Tomkins (left) from Monash University with RMIT University PhD scholar Alan Salek and a ureilite meteor sample. Credit: RMIT University
Strange diamonds from an ancient dwarf planet in our planetary system might have formed soon after the dwarf planet hit a large asteroid about 4.5 billion years earlier.
A group of scientists says they have verified the presence of lonsdaleite, an unusual hexagonal form of diamond, in ureilite meteorites from the mantle of a dwarf planet.
Lonsdaleite is called after the well-known British pioneering female crystallographer Dame Kathleen Lonsdale, who was the very first woman elected as a Fellow of the Royal Society.
