Tsokol is a highly weathered near-surface vein deposit with almost vertical adularia-quartz veins form a continuous mineralised zone. It was first discovered in 1984. Ore shoots within the vein structure are on average 4 m wide, up to 110 m high and vary in length from 50 to 90 m. The ore is free-milling and is expected to yield gold recoveries of up to 95 per cent.

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.

At Tsokol, the underground development decreased by 7% year-on-year with 152 Kt of ore mined and a 29% decrease in the average gold grade to 7.3 g/t. The mine is winding down ahead of expected pillar removal operations during 2019–2020.

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.