Naryn-Gol Creek Sapphire Placer Deposit, Buryatia, Russia

A new gem corundum occurrence has been discovered in the Naryn-Gol Creek placer of the Dzhida volcanic field (Russia). In this placer deposit, sapphire associates with large crystals of garnet, spinel, augite, olivine, enstatite, ilmenite, Ti-magnetite, and alkali feldspar. Such a combination of min...

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Bibliographic Details
Published in:Minerals (Basel) 2022-05, Vol.12 (5), p.509
Main Authors: Kislov, Evgeniy V., Aseeva, Anna V., Vanteev, Vladislav V., Sinyov, Anton Yurievich, Eliseeva, Olga A.
Format: Article
Language:English
Subjects:
Alkali basalts
Augite
Basalt
basalts
Carbon dioxide
Cenozoic
Chemical composition
Coastal inlets
Corundum
Creeks
Creeks & streams
Crystals
Feldspars
Garnet
Geology
Igneous rocks
Ilmenite
Inclusions
Lasers
Lava
Light
Magnetite
microelement composition
Mineralogy
Minerals
Olivine
oxygen isotopes
placer
Placers
Sapphire
Titanium
Volcanic fields
Volcanoes
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Summary:A new gem corundum occurrence has been discovered in the Naryn-Gol Creek placer of the Dzhida volcanic field (Russia). In this placer deposit, sapphire associates with large crystals of garnet, spinel, augite, olivine, enstatite, ilmenite, Ti-magnetite, and alkali feldspar. Such a combination of minerals is typical for the placer deposits associated with alkali basalts widely distributed in Southeastern Asia and Australia. We have also found sapphire crystals in phonotephrites of the nearby Cenozoic alkali-basalt paleovolcano Barun Khobol Pravyi, and in basalt sample and trachybasalt from the valley flood basalts. The chemical composition of sapphire is generally typical for ‘basalt’ corundum: it is rich in Fe, and depleted in Ti and Cr. The δ18O SMOW values of corundum and related megacrysts range from 4.6 to 6.8 ‰, thus corresponding to the isotopic signature of igneous rocks. Etched and corroded surfaces of sapphire and other megacrysts indicate that they are in non-equilibrium with their host alkali basalts. Volatile components, CO2 in particular, played a significant role during sapphire formation as gas inclusions reveal.
ISSN:2075-163X
2075-163X
DOI:10.3390/min12050509