Fluid inclusions in «compact» quartz from the Oka-Urik block (the East Sayan)

Volkova M. G., Nepomnyashchikh A. I., Fedorov A. M.

Zapiski RMO (Proceedings of the Russian Mineralogical Society). 2019. V. 148. N 3. P. 94-101

https://doi.org/10.30695/zrmo/2019.1483.07

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Language: Russian

Abstract

«Compact» quartz of the Oka-Urik block is a new source of ultra-pure quartz raw materials. Large bodies of «compact» quartz are located in the south-western part of the block. The samples are opaque, gray-white, but translucent in thin chips and have the form of a clouded single crystal of quartz. Quartz grains are slightly elongated in one direction. There are two generations of quartz grains. There are single needles and scales of sericite. A distinctive feature of the «compact» quartz from other quartzites of the Oka-Urik block is that fluid inclusions were widely distributed here inside the quartz grains, and only rarely within intergranular spaces. Size of fluid inclusions is to 40 microns. Three types of fluid inclusions by composition were found in the sample of «compact» quartz: water-salt, water and carbon-containing-water. The concentration of salts in fluid inclusions of water-salt composition corresponds to 7—9 wt % NaCl equiv. Chemical enrichment of quartz concentrates showed that the main part of high-temperature water, carbon dioxide and sodium is in fluid inclusions. Based on the data obtained, an enrichment scheme was proposed. Calcination of quartz grits in vacuum at a temperature of 1450 °C for three hours led to a decrease in sodium concentration, as there is an opening of the fluid inclusions inside the grain.

Key words: fluid inclusions, «compact» quart, microthermometry, volatile component, sodium, high-purity quartz concentrate, chemical enrichment, calcination