Finely interspersed accessory and ore minerals of the Verkhnee-Zolotoe deposit

Relevance. The importance of expanding the resource base of copper and polymetals of the Russian Federation: Verkhnee-Zolotoe silver-copper deposit is localized within an ore node specialized in tin and lead – the study of accessories will allow a better understanding of ore formation for deposits that are alien to its surrounding metallogenic specialization. Aim. To establish the nature of the distribution of finely interspersed accessory ore minerals and their conjunction with certain sulfide associations and metasomatic changes. Methods. Electron scanning and optical microscopy in reflected and transmitted polarized light. Results and conclusions. The author has studied the accessory mineralization of rocks in the central part of the Verkhnee-Zolotoe deposit (silver and copper). The genesis of the deposit is debatable: its ore specialization does not correspond to that of the ore region, in which tungsten or tin mineralization is more expected, rather than copper one. Tin and tungsten were diagnosed in core samples taken on the Verkhnee-Zolotoe by ICP-MS method in the absence of their phases with a size of more than 0.1 mm. The study using scanning electron microscopy was carried out to prove the hypothesis that cassiterite and wolframite occur as micron-sized thin inclusions in host rock and veins. Not only cassiterite and wolframite, but native gold, silver, uraninite and monazite as well were found in the collection of 38 polished sections. On the Verkhnee-Zolotoe, gold, tin, tungsten and zirconium form their own minerals, and are not included in the composition of sulfides as impurities. Thus, their association with sulfide veined-interspersed ores probably in the marginal part of the porphyry or, according to other data, HMS system is spatial, not temporal. The formation of small inclusions of gold, silver, monazite and nasturane went along with the formation of interspersed and veined-interspersed sulfide ores – a product of circulation of solutions or fluids in the fractured massif of effusive rocks of volcanic construction. The genesis of scattered cassiterite and scheelite, judging by the peculiarities of its placement, is probably synchronous with propylitization in host volcanites containing sulfide inclusions, and is due to the proximity of objects specializing in tin and tungsten.