Lonsdaleite a ‘Structurally Disordered Form of Ordinary Diamond’

Lonsdaleite first arrived on the diamond scene around 50 years ago, when scientists reported that a large meteorite contained a new form of diamond with a hexagonal structure. The scientific community went on to use lonsdaleite “as an indicator of ancient asteroidal impacts on Earth, including those linked to mass extinctions.”

However, a group of scientists, most based at Arizona State University, have now discovered that lonsdaleite is actually a “structurally disordered form of ordinary diamond.

Arizona State University notes:

So-called lonsdaleite is actually the long-familiar cubic form of diamond, but it’s full of defects,” says Péter Németh. These can occur, he explains, due to shock metamorphism, plastic deformation or unequilibrated crystal growth.

The ASU scientists approached the question by re-examining Canyon Diablo diamonds and investigating laboratory samples prepared under conditions in which lonsdaleite has been reported.

Using the advanced electron microscopes in ASU’s Center for Solid State Science, the team discovered, both in the Canyon Diablo and the synthetic samples, new types of diamond twins and nanometer-scale structural complexity. These give rise to features attributed to lonsdaleite.

Click here to read the full report from Arizona State University.