Fahlore crystals and aggregates from the Darasun gold deposit show complex rhythmic-oscillatory chemical zoning resulting from crystal growth and coupled dissolution-reprecipitation reactions. Formation temperatures of these zonal fahlores were determined using the Raabe Sack (1984) geothermometer and results of 2780 microprobe analyses. Fahlore is a nearly complete solid solution between tetrahedrite-(Zn) and tennantite-(Fe) with ratios of Sb/(Sb + As) of 0.02–0.85 and Fe/(Fe + Zn) of 0.15–1.00, and exhibits a negative interdependence between these ratios consistent with the thermochemical incompatibility of As and Zn in fahlores. Fahlore compositions in the deposit exhibit scale invariance. The crystallization temperatures for zonal growth crystals of tennantite-(Fe) are from 115 to 314°C, vary from grain to grain and from rhythm to rhythm in individual grains, are similar to those for zonal-heterogeneous fahlore aggregates, from 115 to 290°C, and are in agreement with temperatures obtained for fahlores using fahlore-sphalerite (177–395°C) and fahlore-bournonite-seligmannite (117–316°C) geothermometers, with all of these temperatures being lower than the 284–395°C homogenization temperatures of fluid inclusions in coexisting quartz. Although overlapping in temperatures the general sequence of fahlores precipitated with decreasing temperature was: tetrahedrite + sphalerite → tennantite + sphalerite → fahlore + bournonite-seligmannite → zoned tennantite-(Fe) grains → pseudomorphic zonal-heterogeneous fahlore aggregates. The reasonable temperatures suggest that oscillatory zoning was created at nearly constant temperature and Fe(Zn)–1 exchange potential. About 30–40

Rare minerals represented by oxides, fluorides, F-carbonates and REE arsenates in association with monazite-Ce, monazite-Th, xenotime-Y and zonal REE fluorite were identified in the rare-metal ores of the Sn–W deposits of Lesser Khingan, Amur region. Rare lanthanide minerals are described, including fluocerite, bastnaesite, and gasparite-Ce, which was found for the first time in Russia in the Sn–W greisens, and chernovite-Y, the second find in the greisens of the Russian Far East. The influence of arsenic fluids at the late hydrothermal stage caused the replacement of xenotime-Y and monazite-Ce by diverse REE minerals with different lanthanide proportions. It is found that these minerals differ in chemical composition from the same minerals described in other deposits elsewhere. Due to the variable valence state of arsenic and the complete isomorphism between rare earths, arsenates can be used as indicators of redox conditions of their deposition.

The mineral and chemical composition of bauxites from the Chadobets uplift of the Siberian Platform is the total product of laterites on aluminosilicate rocks (source of aluminum) and on alkaline rocks and carbonatites (source of rare earth elements (REEs), Nb, Ta, Th, U, etc.). The laterization of these rocks and subsequent denudation led to the formation of unique bauxite deposits with a high content of rare and REEs. Supergene minerals of the laterite weathering crust are in a dispersed microcrystalline and amorphous state, which complicates their study and the choice of methods for extracting useful components. Precision methods were used to establish the forms and compositions of the main supergene minerals, biomineral films, biomorphoses, and the distribution of rare and rare earth elements in them.

Ванадиевый травяно-зеленый дравит обнаружен в маломощных (до 10 см) кварцевых жилах, пересекающих черные кремнистые сланцы позднего протерозоя, обогащенные ураном и ванадием (до 50 ppm). Содержание V2O3 в – до 5.34% при низком содержании железа и повышенном магния. По всей вероятности, ванадий занимает в структуре минерала в основном Z-позицию. Получены спектры диффузного отражения в диапазоне 350–2500 нм и люминесценции при возбуждении УФ-излучением N-лазера. Появление ванадия в качестве хромофора и люминофора в метаморфических породах интерпретируется как индикатор древних океанических структур на континентах. В статье 11 рисунков, 2 таблицы, 21 литературная ссылка.

The distribution of REEs and some minor elements in tourmalines of different associations and deposits of the Russian Far East is studied by the methods of ICP-MS, ICP-MS with laser ablation and scanning electron microscopy. The duality of REE speciation in tourmaline is established: in high-temperature varieties, most REEs (mainly HREEs) are incorporated in rare minerals (monazite, xenotime, zircon, and F–Ce–Y carbonate), whereas hydrothermal ores are characterized by isomorphic incorporation of LREEs in the mineral structure, as well as by a fine admixture of zircon at the expense of detrital clasts in flyschoid rocks with the zones of tourmalinization.

The Vysokogorskoe tin deposit is spatially and temporally related to the granite magmatism. The important ore bodies are dyke-like mineralised fluid-magmatic breccia. A fluid inclusion study revealed a coexistence of the hypersaline aqueous fluid and the vapor-rich fluid assuming the exsolving of the boiling fluid at the crystalization of granodiorite-porphyry. The boiling fluid infiltrated the granite-porphyry dikes and breccias. The metal-bearing magmatic fluid was mixed with the nonmagmatic (meteoric) fluid during the breccia formation.

Geochemical data on cassiterite from tin deposit are used to estimate informative trace-element features of this mineral with the application of pattern recognition methods. The research is centered on the comparative analysis of geochemical associations in cassiterite from various mineralized zones and fluid-magmatic breccias. Informative intervals of parameters (elements) are revealed for various mineralized zones and breccias and make it possible to recognize the studied classes. Our results suggest that trace elements in cassiterite from various zones show different distributions, a fact implying complicated conditions of mineral-forming processes that produced the zones and breccias.