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The Um samiuki deposit is a Precambrian volcanogenic massive sulfide mineralization. Massive and disseminated Zn-Cu-Pb-Ag sulfides are hosted in felsic volcanics and pyroclastics The ores show primary depositional and metamorphic-deformational features. The hypogene sulfides comprise sphalerite, chalcopyrite, galena, tetrahedrite-tennantite, pyrite, bornite, :arsenopyrite and molybdenite, whereas covellite is a supergene phase. Bornite, tetrahedrite-tennantite and covellite are generally Ag-rich with an average Bg contents of 0.76, 0.82, and 1.69 wt.%, respectively. Nine silver minerals were identified; hessite, electrum, cervelleite, freibergite, acanthite, benleonardite, stephanite, native silver and mckinstryite. The different silver minerals were precipitated simultaneously with silver-bearing sulfides from Ag-rich fluids under near-neutral and oxidizing conditions. Hypogene and supergene processes participated in the precipitation of silver and silver-bearing minerals.