Meteor Strikes Turn Graphite Into Diamonds

Diamonds are prised the world over as a precious jem worth spending large amounts of money on.This is curious as diamonds are just a different form of carbon from the ones that we know as graphite or even coal.

High pressure can turn a soft form of carbon namely graphite, (used as pencil lead) into an extremely hard form of carbon, diamond. Could the same thing happen when a meteor hits graphite in the ground?

Scientists have predicted that it could, and that these impacts, in fact, might be powerful enough to produce a form of diamond, called lonsdaleite, that is even harder than regular diamond.

The existence of lonsdaleite has been disputed, but we’ve now found compelling evidence for it.

says Glenzer, the co-principal investigator of a study published March 14 in Nature Communications.

The team heated the surface of graphite with a powerful optical laser pulse that set off a shock wave inside the sample and rapidly compressed it. By shining bright, ultrafast X-rays from SLAC’s X-ray laser Linac Coherent Light Source (LCLS) through the sample, the researchers were able to see how the shock changed the graphite’s atomic structure. LCLS is a DOE Office of Science User Facility.

We saw that lonsdaleite formed for certain graphite samples within a few billionths of a second and at a pressure of about 200 gigapascals – 2 million times the atmospheric pressure at sea level,

says lead author Dominik Kraus from the German Helmholtz Center Dresden-Rossendorf, who was a postdoctoral researcher at the University of California, Berkeley at the time of the study.

These results strongly support the idea that violent impacts can synthesize this form of diamond, and that traces of it in the ground could help identify meteor impact sites.

Source

So if you are tempted to look for meteors to collect, you find one where the pressure has turned graphite into diamonds. Good luck.