Sopka Kvartsevaya was discovered in 1969 and is a low sulphidation epithermal gold and silver deposit. It consists of several linear alteration zones enclosing relatively narrow adularia-quartz and quartz-carbonate veins. The main gold-bearing zone extends for 2.2 km dipping at low to moderate angles. It contains five high-grade shoots with adularia quartz veins, enveloped by a wide halo of alteration, which contains low-grade zones. In addition to native gold, the main carriers are electrum and kustelite.

Gold–silver mineralization in Northeast Asia is controlled by 9-th volcanic belts of different ages that are superimposed on cratonic, passive continental-margin, island-arc, and oceanic terranes. The brief overview of volcanic belts in Northeast Asia presented in this communication shows that the mineralogy of the epithermal gold-silver deposits in these belts depends on the metallogeny and composition of rocks in structures of the basement and, probably, the Precambrian basement.

This giant belt is 3000 km long is composed of subaerial volcanic rocks. Relative to the oceanic margin, the Okhotsk-Chukot belt is divided into the inner, outer, and perivolcanic zones. The intricate structure of terranes of the basement and the Okhotsk-Chukot belt produced a diversity of epithermal deposit types. The inner zone of the belt mainly accommodates porphyry Cu-Mo deposits. The outer and perivolcanic zones include gold-silver and silver-tin ore deposits. The gold-silver subtype is more widespread in the outer zone (Karamken, Valunisty, Kupol, and Dvoinoi). Deposits of the silver subtype (Dukat, Lunnyi, Arylakh, Golcovy and others) are confined to the volcanic rift located between the Yana Kolyma and Omolon terranes of the Okhotsk-Chukot belt.

At Sopka, the volume of ore mined increased by 140% to 627 Kt. The open-pit mine life at Sopka has been extended to the second half of 2019 as step-out drilling identified incremental high quality mineralisation that extends into the pit walls.

The Kubaka plant currently uses only conventional CIP cyanidation technology. Run-of-mine ore is crushed in a jaw crusher, followed by two-stage milling (SAG mill and ball mill), thickening, CIP leaching, desorption, electrolysis, carbon regeneration and doré smelting. This processing option will continue to be utilised in the long term for ores with low silver content, such as ores from the Birkachan and Tsokol mines.