The article describes magnetite–sulfide assemblages of minerals containing native gold and tellurides in the Pb–Zn–Fe ores of the Aktash skarn deposit in Western Karamazar (Tajikistan). Gold–silver–telluride mineralization is represented by products of a multistage ore process. It has been established that native gold is concentrated both in magnetite and in association with sulfide minerals. A decrease in the fineness of native gold from its early to late varieties was revealed: 725–905‰ in magnetite → 656–699‰ in pyrite-pyrrhotite ores → up to 290‰ in association with galena and bismuth-bearing minerals. The regular decrease in the fineness of native gold and paragenetic relationship with various bismuth minerals (native bismuth, bismuthite, aikinite, Ag–bearing aikinite, uytenbogaardtite, Ag–Au–Bi–S phases) reflect a decrease in temperature and sulfur fugacity of mineral-forming fluids. Tellurides are found in magnetite-chalcopyrite-pyrite-pyrrhotite ores and are represented by tsumoite, pilsenite, hessite and stützite. Electron backscatter diffraction (EBSD) patterns of tsumoite and pilsenite confirmed the predominant presence of tsumoite in the ores.

The rare mineral zavaritskite has been identified in sulfide–magnetite ore of the Aktash skarn deposit, northern Tajikistan, and has been studied by optical and scanning electron microscopy, and backscattered electron diffraction. Zavaritskite is associated with native bismuth, chalcopyrite, galena, supergene bismuth oxides, and anglesite. It is the first occurrence of zavaritskite not only at the Aktash deposit, but for all of the Kurama bismuth subzone of the Chatkal–Kurama metallogenic zone.

The article describes the production experience and a static analysis of the results of field measurements during the excavation of mine workings by contour blasting. A decision to perform field measurements during excavation and a statistical analysis of the results is made in order to assess the possibility of their use for normalization. The high degree of correspondence of the actual distribution of the results of field measurements to the normal law makes it possible to successfully use all the statistical characteristics of the theoretical distribution in analytical studies and in solving problems of improving technology and normalizing using the contour blasting method. The bulk of the results of downhole measurements of the parameters of contour blasting is in a narrow range of two standards ẋ ± S_x which allows us to further consider these ratios as criteria for the development of regulatory tolerances for the execution of a Blasting Pattern (BP) that provides practically acceptable contouring accuracy and the quality of the newly formed surface space.

The distribution of trace elements in sulfdes from various ores of the Aktash magnetite-polymetallic deposit (Tajikistan) is studied using LA-ICP-MS method. Sulfdes partly replace banded magnetite ores. Each sulfde type exhibits specifc geochemical features. Galena from sulfde-magnetite ores contains the higher amount of elements of «high-temperature» association (Bi, Ag, Cu) than galena from pyroxene-sphalerite ores, which, in addition to Ag and Bi, also contains higher amount of elements of «medium-temperature» association (Se, Te, and Sb). Sphalerite from sulfde-magnetite and chlorite-pyrrhotite ores contains higher Fe, Cd and Mn amount than sphalerite from pyroxene-sphalerite ores, which is characterized by elevated Co and As contents. Pyrite is depleted in trace elements except for As, the content of which is maximum compared to other sulfdes. The Ag, Se, Bi, Zn, Cd and Ni contents of chalcopyrite from chlorite-pyrrhotite ores are higher than in chalcopyrite from sulfde-magnetite and pyroxene-sphalerite ores. Chalcopyrite from pyroxene-sphalerite ores is characterized by elevated Pb, As, Ge, Te and Sb contents. Relatively high Co, Ni and Se contents are determined in pyrrhotite. In addition to Fe, Cu, Zn, Pb and Au, which form minerals in all types of ores, we suggest by-product extraction of following elements from complex sulfde-magnetite, chlorite-pyrrhotite and pyroxene-sphalerite ores (the Bi, Ag, Se and Te contents of galena and Cd content of sphalerite are shown in brackets): Bi (19520–24650 ppm), Ag (7907–9650 ppm), Se (397–606 ppm) and Te (276– 436 ppm) from galena concentrate and Cd (8525–27670 ppm) from sphalerite concentrate.

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.

The article discusses the features of the formation of a dynamic stress field and manifestations of rock pressure around hydraulic tunnels. The results of the calculation of the dynamic stresses in the rock mass of the surrounding hydraulic tunnels, the turbine hall, the transformer room of the Rogun HPP are presented. Analytical studies are confirmed by data obtained as a result of observations of the behavior of workings under dynamic loads in production conditions at the construction of hydroelectric power plants. The influence of blasting operations on the development according to the form adopted in hydraulic engineering was also considered. Based on the studies carried out in the chamber sections of the turbine hall and the transformer room of the Rogun HPP, it was found that the maximum and minimum principal stresses σ₁ Λσ₃ are horizontal, while the stress σ₁ in direction coincides with the longitudinal axis of the turbine hall, and σ₃ with its transverse axis the average principal stress σ₂ is vertical.