The Birkachan mineralisation is located in a 150 to 200 m wide zone. The mineralisation comprises two distinct types: gold-silver veins and disseminated stockwork. The individual veins generally have an average width of up to 2-8 m, extend up to 200-250 m along strike and down-dip and carry gold grades of up to 8 to 14 g/t. The stockwork comprises mineralised zones of 60 to 80 m thick extending 2.5 km along strike and 150 to 200 m down-dip from the surface and grading 1 to 3 g/t of gold.

The Kedon marginal volcanic belt formed on the continental crust in the Middle Paleozoic during a period of 30-35 Ma. Relicts of this volcanic belt are retained as fragments in the Omolon cratonic terraine. The belt is composed of differentiated subaerial red-colored volcanic rocks coupled with compositionally similar subvolcanic and hypabyssal intrusions. The volcanic rocks belong to the calc-alkaline series. There are two types of epithermal volcanic mineralization in the Kedon volcanic belt. Gold mineralization (Au/Ag=1:1-1:5) is developed in the Kubaka, Birkachan, and Elochka deposits. Whereas the gold-silver mineralization (Au/Ag=1:10-1:50) is developed in the Sedoi, Yunyi and Ol'cha deposits. The large Kubaka and Birkachan deposits are characterized by a low content of sulfides (<0.1 and 0.1-0.5%, respectively). The ores are mainly composed of gold, electrum, and pyrite.

Birkachan is an underground mine a part of Omolon hub (comprises of the Kubaka processing plant and operating mines - Tsokol, Birkachan, Olcha, Yolochka).

Mining at Birkachan open-pit was completed in Q4 2020.

Access to ore bodies at Birkachan underground carried out via adits.

All parts of the hub are centered around the 850 Ktpa Kubaka CIP plant, which serves as the processing facility for operating mines in the area and future near-mine feedstock. In addition, the Company operates a 1 Mtpa seasonal heap leaching circuit at the Birkachan mine.

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.