Dwarf planet diamonds could hold the key to stronger machine parts for mining

Scientists say that strange diamonds from an ancient dwarf planet in our solar system could lead to the production of ultra-hard machine parts.

The researchers from Monash University, in collaboration with CSIRO, RMIT University, the Australian Synchrotron, and Plymouth University have confirmed the existence of lonsdaleite – a rare, hexagonal-shaped diamond believed to be much stronger and harder than its more typical cubic cousin – in ureilite meteorites from a dwarf planet’s mantle.

The study provides evidence of lonsdaleite’s formation in nature, offering clues to synthetic production that could make more durable machine parts, which CSIRO scientist Colin MacRae says could have enormous implications for industries like mining.

“If something that’s harder than diamond can be manufactured readily, that’s something industry would want to know about,” MacRae said.

Ureilite cross-section showing lonsdaleite, captured with CSIRO’s electron prob microanalyser (EPMA). Iron in red, magnesium in green, silicon in blue, lonsdaleite in yellow, and diamond in pink. Picture: CSIRO

Making tiny, ultra-hard machine parts

Lead study author Professor Andy Tomkins said the current method for producing industrial diamonds involves chemical vapour deposition, in which diamonds are formed onto a substrate from a gas mix at low pressures.

“We propose that lonsdaleite in the meteorites formed from a supercritical fluid at high temperature and moderate pressures, almost perfectly preserving the textures of the pre-existing graphite,” he said.

“Later, lonsdaleite was partially replaced by diamond as the environment cooled and the pressure decreased. Nature has thus provided us with a process to try and replicate in industry.

“We think that lonsdaleite could be used to make tiny, ultra-hard machine parts if we can develop an industrial process that promotes replacement of pre-shaped graphite parts by lonsdaleite.”