- The full study – Tomkins et al: Sequential lonsdaleite to diamond formation in ureilite meteorites via in situ chemical fluid/vapour deposition – is published in PNAS, DOI: 10.1073/pnas.2208814119.
“These findings help address a long-standing mystery regarding the formation of carbon phases in ureilites that has been the subject of much speculation. They offer a novel model for diamond formation in ureilites that settles contradictions in the existing concepts. Typically containing larger abundances of diamond than any known rock, ureilite meteorites are arguably the only major suite of samples we have from the mantle of a dwarf planet.
"The parent asteroid was catastrophically disrupted by a giant impact while the mantle was still very hot, creating the ideal conditions for lonsdaleite then diamond growth as the pressure and temperature decreased in a fluid and gas-rich environment.”
“Ureilite meteorites are one of the most abundant sources of diamond in the Solar System. However, any occurrences are typically at the micro – and even nano – scale, so they can be hard to see. Using advanced analytical microscopy, we can not only identify these tiny crystals in their host rocks but also probe their precise chemistry and structure, therefore unravelling their formation and evolution. This led to the identification of lonsdaleite and a new method of formation, which could potentially be replicated on Earth in order to synthetically produce this industrial mineral on a commercial scale.”
“The use of electron microscopy within meteorite studies is unparalleled in analytical science. The non-destructive nature of most EM techniques means we can study these extra-terrestrial objects in unprecedented detail (up to several million times magnification), revealing what they are made of and how they formed. However, we can also do so without damaging these rare samples, ensuring they are preserved for future science with new technological advances, and for future generations to enjoy.”
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