The use of tourmaline in geochemical prospecting for gold and copper mineralization

Chemical composition, unit cell parameters, and trace elements of tourmalines from Mesozoic gold-quartz-sulphide and gold-bearing copper-porphyry ore-magmatic systems of the Trans-Baikal area and Mongolia show that they belong to the specific schorl-dravite highly ferruginous oxytourmaline series. They are low in alumina (Al₂O₃ = 16–33%) and have MgO contents (up to 10%) and Fe₂O₃ (1%). There is a direct correlation of unit cell parameters (a,c,V) with total iron, which permits composition estimates from X-ray diffraction analyses. As a rule, these tourmalines contain high concentrations of Au, Pb and Cu, which are mainly hosted by inclusions of native gold and ore minerals. The highest As abundances are contained in the tourmalines of the copper-porphyry field.Two trends of isomorphic replacement are related to increasing Fe content of oxyferruginous tourmalines:(1) “Acid leaching” trend (less ferruginous part of the series) Mg + Fe²⁺ + 4Al + 40 4Fe³⁺ + 2 + 4(OH,F); and (2) “conjugate deposition” trend Mg + 1.5Fe²⁺ + 1.5Al + 4(OH,F) 4Fe³⁺ + 4O.These features distinguish tourmalines from gold-bearing systems from schorl-dravites of tin and rare-metal deposits. They may be used in metallogenic analyses, interpretation of the origin of primary and secondary anomalies, and assessment of the type and zonation of ore fields.     

Uranium in saline lakes of Northwestern Mongolia

Analysis of major- and trace-element compositions of water in hypersaline soda closed basin lakes of Northwestern Mongolia and Chuya basin (Gorny Altai) shows high enrichment in ²³⁸U (up to 1 mg/l). Proceeding from new data, uranium accumulation in water has been attributed to (i) location of the lakes and their watersheds in potential provinces of U-bearing rocks and (ii) uranium complexing with carbonate in presence of carbonate (bicarbonate) anions. Among the explored hypersaline soda lakes of the area, the greatest uranium resources are stored in Lake Hyargas Nuur (about 6000 ton).     

Uranium in Saline Lakes of Mongolia and Adjacent Areas

正1 Introduction Increasing demand for uranium raw materials for the nuclear industry has stimulated interest in non-traditional sources,including hydromineral ones[Qin,2009].Those are saline lakes located in the uranium ore districts.Accumulation of uranium in such lakes results from the leaching of uranium from the rocks by surface and ground     

Geochemistry and chemical evolution of saline lakes of Western Mongolia

This paper presents data on the major and trace element composition of saline lakes of western Mongolia. The main geochemical types of lakes distinguished in the study are soda-, chloride-, and sulfaterich lakes. Lake water equilibria with major carbonate, sulfate, chloride, and other rock-forming minerals were calculated. The results show that the major factors controlling the formation of each lake type include evaporation and water-rock interaction processes, and the latter factor plays a critical role in freshwater and soda lakes and only a minor role in chloride lakes. Special attention was given to the soda lakes and the factors controlling lake water chemistry.