Radiation-induced diamond formation in uranium-rich carbonaceous materials

Nanometer-sized diamonds were identified by transmission electron microscopy in a uranium-rich, coal-like carbonaceous assemblage of Precambrian age. This observation, together with estimates of formation efficiencies, supports the hypothesis that diamond can form in carbonaceous material irradiated by the radioactive decay products of uranium. The results also suggest that the formation of carbonados cannot be sufficiently explained by a radiation mechanism alone.