Diamonds from tuffisite on the Yenisei ridge

First complete mineralogical and geochemical studies were conducted for diamonds and tuffisites-like source rocks identified at the Eniseyskiy Ridge. Studied diamonds are characterized by green color, cubo-octahedral morphology, moderate nitrogen content, and unaggregated nitrogen structural defects. The xenomineral film on the surface of diamond consist of a variety of native metal, carbide, sulfide and sulfate, halosulfide and oxide phases. The main micro-impurities are presented by Ni, Fe, Mn. The individual crystals as well as the diamonds in whole vary significantly in the isotopic composition of carbon. The results confirm the widespread dissemination of the diamonds on the Siberian Platform and their polygenesis.