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Large-scale reserves of uranium in Au-U deposits of the Elkon ore district are composed of newly discovered polyphase uranium-titanium metagel (UTM). Before, it was assumed that brannerite is the major mineral of these ores. However, it has been revealed that brannerite and uranium oxides and silicates are minor components of mineralization. Succession of UTM phases selection, their relations with brannerite are characterized. Few groups of UTM has been revealed by composition of major and trace elements. The filter cake of acidic leaching of a technological sample with residual uranium concentration of 0,02 wt.% and grain size of -0.16 mm was investigated. As it was established, the major part of uranium is in the fine grained UTM phases submerged in quartz-feldspar matrix of the cake particles. Taking into account a small size of the uranium phases (first microns, rarely n-10 mkm), recrusing of the ore to smaller grades will unlikely lead to a noticeable uranium yield into final product.

A wide range of the temperatures of hydrothermal fluid regime (430-103 °C) has been revealed in the result of microthermometric study of the fluid inclusions in the minerals of pre-ore and post-ore stages developed at the Elkon deposit. Average temperatures, as well as the temperature variation are similar for both pre-ore and post-ore stages. It allows sure determination of temperatures of uranium ore formation as 400-120 °C. Fluids possessed Na-chloride, rarely Na-chloride-carbonate composition and moderate salinity (6-16 wt. % · NaCl equiv.). The wide range of tem-peratures confirms an assumption made before that various temperatures were the reason of formation of uranium mineralization both in the form of predominantly amorphous phase (U-Ti-metagel), as well as the rarely crystalline form (brannerite). Abrupt temperature decrease was apparently the main factor of the ore precipitation.