Bismuth mineralization is studied in sulfde-magnetite ores of the Aktash deposit in Western Karamazar (Northern Tajikistan), which is hosted in the Middle–Upper Paleozoic sedimentary and intrusive rocks. The higher Bi contents are related to the presence of its numerous minerals including native bismuth, bismuthine, Cu–Ag–Pb–Bi sulfosalts (wittichenite, emplectite, aikinit, friedrichite and salzburgite) and Bi oxides (bismite, zavarazkite) in assemblage with galena, chalcopyrite, garnet, pyroxene, epidote and anglesite. The Ag-bearing varieties of wittichenite (Cu,Ag)3BiS3, aikinite (Pb,Ag)CuBiS3 and galenobismuthite (Pb,Ag)Bi2S4 are identifed. Most of the bismuth minerals were frst described not only for this deposit, but for the ore region as well. The mode of occurrence of Bi can be used to refne the genetic features of the deposit. Figures 4. Tables 3. References 27.

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The article discusses the possibility of using reinforced cementation of rocks in order to consolidate the rock mass around underground workings and prevent water filtration into the turbine room and underground transformer room and tunnels of the Rogun HPP based on the experience of using this method in the construction of underground structures of the Kariba (Rhodesia) and Roselan-Bati HPPs (France). In recent years, comprehensive studies of rock masses containing the main underground structures of the Rogun HPP made it possible to clarify the current state of these masses and update the characteristics of their elastic and deformation strength properties obtained at the technical design stage. The results of the performed calculations testify to the normal operation of the anti-seepage circuit of the dam and indicate high efficiency of the drainage system of the pressure head unit.

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