Naryn-Gol Creek Sapphire Placer Deposit, Buryatia, Russia

A new gem corundum occurrence has been discovered in the Naryn-Gol Creek placer of Dzhida volcanic field (Russia). In this deposit, sapphire associates with large crystals garnet, spinel, augite, olivine, enstatite, ilmenite, Ti-magnetite, and alkali feldspar. Such a combination minerals is typical for deposits associated basalts widely distributed Southeastern Asia Australia. We have also found phonotephrites nearby Cenozoic alkali-basalt paleovolcano Barun Khobol Pravyi, basalt sample trachybasalt from valley flood basalts. The chemical composition generally ‘basalt’ corundum: it rich Fe, depleted Ti Cr. δ18O SMOW values related megacrysts range 4.6 to 6.8 ‰, thus corresponding isotopic signature igneous rocks. Etched corroded surfaces other indicate that they are non-equilibrium their host Volatile components, CO2 particular, played significant role during formation as gas inclusions reveal.