Siberia has a prominent position in Russia, in terms of mineral resources and mineral production including copper, nickel, PGM's, uranium, molybdenum, tungsten, tin, manganese, gold, silver, lead, tantalum–niobium, rare earths, diamonds and many other mineral commodities. These resources are represented by a vast array of mineral systems and deposit styles in their respective terranes spanning the Precambrian and Phanerozoic geological history. These mineral systems include VHMS and SEDEX lead–zinc, orogenic gold, sediment- and shear-zone hosted to intrusive-related silver to silver-tin, alkaline gold to gold–uranium and uranium, porphyry copper and copper–molybdenum, epithermal gold, gold–silver, silver, gold–antimony, mercury, uranium–fluorite, various granite-related deposits (W, Mo, Sn, Be, Ta, Co–Ni, etc.) including those associated with peralkaline granites (Nb–Ta–Zr–REE), skarn iron, lead–zinc, gold, tungsten, carbonatite tantalum–niobium, niobium–REE and REE, magmatic copper–nickel–PGM sulfide, PGM and mafic intrusion-hosted iron–titanium–vanadium deposits, and diamondiferous kimberlites. Some deposits are large and superlarge including the well-known Noril'sk nickel–copper–PGM and Udokan copper deposits, the Sukhoi Log, Olympiada, Nezhdaninskoe, Kubaka, Kupol gold deposits, the Dukat and Prognoz silver deposits, and the Yakutian diamondiferous kimberlites. Apart from the above-mentioned giant deposits, several others are poorly known and/or unknown to western geoscience. The study of these mineral systems can significantly contribute to our further understanding of the metallogeny of cratons and orogenic belts, orogenic collages, and anorogenic settings. This provides additions to, and further development of, existing classifications and genetic models of mineral systems, allowing researchers to elucidate unknown or poorly studied mineral systems and styles found in Siberia, and to search for some other important styles that appear to be missing, although they are present in other regions with similar geological and tectonic settings.

We have revealed early productive disseminated pyrite-arsenopyrite mineralization with invisible gold in tectonic zones and late nest-veinlet gold-polysulfide mineralization with free gold in zones of silicified rocks at the Suzdal’ (Suzdal’skoe), Zherek, and Bol’shevik deposits in eastern Kazakhstan, localized within black shales. Two varieties of arsenopyrite differing in morphology, chemical composition, and gold contents have been established in them: acicular-prismatic and tabular. Gold was determined by a specially elaborated technique ensuring a detection limit of 30 ppm Au. Acicular-prismatic arsenopyrite is the main ore mineral of the early productive stage of mineralization; it has high gold contents (1400–5360 ppm) and a nonstoichiometric composition (S/As = 1.2) and is slightly depleted in Fe. The absence of correlation between the contents of the main arsenopyrite components and gold, and the strongly uneven distribution of gold among the mineral grains, and within a grain point to the presence of invisible gold, as elemental particles deposited together with arsenopyrite. Tabular arsenopyrite is abundant at the Suzdal’ deposit, where gold-polysulfide mineralization and argillization are widespread. It has low gold and high antimony contents and a stoichiometric composition. Visible gold usually grows over tabular arsenopyrite. The isotopic composition of sulfur of acicular-prismatic arsenopyrite and globular-crystalline pyrite, formed at the early mineralization stages, is characterized by δ34S = 0.0 to –3.3‰ and evidences a mantle source of sulfur with a partial borrowing of crustal sulfur. The tabular arsenopyrite and other sulfides of the second productive mineralization show a lighter isotopic composition of sulfur (δ34S = –7.7 to –10.2‰), which is due to sulfur fractionation under high oxygen fugacity at the late ore deposition stage. The coexistence of two sets of arsenopyrite of different morphologic varieties and compositions at the deposit points to a long ore deposition, the coexistence of mineralization formed at different stages, and the evolution of physicochemical parameters.

A comparative analysis of morphology and geochemistry was made for gold from the primary ores and weathering crust of the Suzdal' gold deposit, Eastern Kazakhstan. The deposit is localized in Carboniferous carbonaceous-terrigenous strata and is of gold-sulfide type. Study of gold from primary ores showed that it occurs mainly in two species: free and so-called invisible. Free gold is crystallomorphic segregations and irregular-shaped grains up to tens of microns in size; it occurs in intergrowths with sulfides, quartz, carbonate, and mica-chlorite aggregate. Most of gold particles have a fineness of 930–980‰, with some grains showing wide variations in composition. Invisible gold (probably chemically combined) is present in fine-acicular arsenopyrite and, less frequently, pyrite. Being transported to the weathering crust, all this gold served as a source for “neogenic” gold of diverse morphologic forms. We recognized crystalline (isometric, prismatic, acicular, and tabular) particles and drusoid gold aggregates in the form of exotic intergrowths of crystallomorphic and sinter-shelly grains. The grains tend to coarsen from bottom to top of the weathering crust. Several generations of gold of different granulometric classes are observed. We have revealed seed and layer growth and dissolution structures in crystals of early generations overgrown with fine grains. All these gold varieties are associated with hypergene minerals. Most of this gold is of high fineness (on the average, 995‰). The hypergene gold particles are chemically homogeneous high-grade, without rims. The results of studies suggest that the high-grade hypergene gold formed in the weathering crust as a result of the dissolution of invisible gold of sulfides and its local redistribution and deposition in oxidizing media. This is also evidenced from the tendency of gold to coarsen from bottom to top of the weathering crust. A distinctive feature of secondary gold is well-expressed crystals and their great diversity.