Аннотация:The distribution of uranium between diff erent phases of cast stone matrices fabricated by fusion of basalt and uranium-bearing SiO2-based collectors was investigated. It was found that matrices created by fusion of basalt with SiO2 consist of glass, quartz, and spinel as the main phases. A study of the physicochemical properties of collectors based on 30 wt % UO2(NO3)2-bearing SiO2 showed that, after thermal treatment at a temperature of 973 K, they contain uranium only in the form of UO3. The uranium leaching in H2O from SiO2 after its thermal treatment, as well as from a basaltic melt with SiO2, was estimated.