The Kupol and Dvoinoye orebodies are both high grade gold-silver vein deposits, and both are currently underground mining operations.

The Kupol deposit is located in the 3,000 km long Cretaceous Okhotsk-Chukotka volcanogenic belt. This belt is interpreted to be an Andean volcanic arc type tectonic setting, with the Mesozoic Anui sedimentary fold belt in a back-arc setting to the northwest of the Kupol region. Russian 1:200,000 scale mapping indicates that the Kupol deposit area is centred within a 10 km wide caldera, along the northwestern margins of the 100 km wide Mechkerevskaya volcano-tectonic “depression”, an Upper Cretaceous bimodal nested volcanic complex. The volcanic succession in the area is 1,300 m thick and consists of a lower sequence of felsic tuffs and ignimbrites, a middle sequence of andesite to andesite-basalt flows and fragmentals capped by felsic tuffs and flows.

The property is underlain by shallow eastward dipping andesite lithic tuffs, feldspar hornblende porphyry andesite, and andesite-basalt (trachytic andesite) flows. The andesitic volcanic units are intruded by massive to weakly banded rhyolite dykes, rhyolite and dacite flow-dome complexes, and basalt dykes. The main deposit strikes north-south and has been divided into six contiguous zones. From north to south these are: North Extension, North, Central, Big Bend, South, and South Extension.

The Kupol deposit is considered to be an example of a low-sulphidation epithermal deposit. Low-sulphidation epithermal deposits are high-level hydrothermal systems, which vary in crustal depths from depths of about 1 km to surficial hot spring settings. Host rocks are extremely variable, ranging from volcanic rocks to sediments. Calc alkaline andesitic compositions predominate as volcanic rock hosts, but deposits can also occur in areas with bimodal volcanism and extensive subaerial ashflow deposits. A third, less common association is with alkalic intrusive rocks and shoshonitic volcanics. Clastic and epiclastic sediments in intra-volcanic basins and structural depressions are the primary non-volcanic host rocks.

Mineralization in the near surface environment takes place in hot spring systems, or the slightly deeper underlying hydrothermal conduits. At greater crustal depth, mineralization can occur above, or peripheral to, porphyry (and possibly skarn) mineralization. Normal faults, margins of grabens, coarse clastic caldera moat-fill units, radial and ring dyke fracture sets, and hydrothermal and tectonic breccias can act as mineralized-fluid channelling structures. Throughgoing, branching, bifurcating, anastomosing and intersecting fracture systems are commonly mineralized. Mineralization forms where dilatational openings and cymoid loops develop, typically where the strike or dip of veins change. Hanging wall fractures in mineralized structures are particularly favourable for high-grade mineralization.

The mineralization typically includes pyrite, electrum, gold, silver, and argentite. Other minerals can include chalcopyrite, sphalerite, galena, tetrahedrite, and silver sulphosalt and/or selenide minerals. In alkalic host rocks, tellurides, roscoelite and fluorite may be abundant, with lesser molybdenite as an accessory mineral.

The Dvoinoye gold-silver deposit is located within the Okhotsk–Chukotka Volcanic Belt (OCVB), an Andean-type continental margin magmatic arc that extends southwest from the Chukotka Peninsula along the East Asian coastline. The OCVB has four distinct segments: two roughly northwest trending segments separated by a longer northeast trending zone and a shorter northeast zone at the far southwest end.

Host rocks at Dvoinoye are Late Cretaceous intermediate-felsic volcanics of the Tytylveyem Suite, which is divided into three units. At Zone 37, the host rock is assigned to the lower unit of the Tytylveyem Suite. The main host rock here is porphyritic dacite lava, containing 20% to 30% phenocrysts (plagioclase, pyroxene and potassium feldspar), in a siliceous aphanitic matrix. Other components of the local geology include crosscutting pyritic hydrothermal breccias that may mainly affect the tuff units. Their distribution and geometry are unclear but at least part of the Zone 37 vein is hosted by narrow siliceous pyritic milled breccias that may be related to larger volume hydrothermal breccias.

The Dvoinoye veins are close to the northern margin of the Ilirney granitic massif. As a result, there is substantial development of dykes, sills, and plugs of generally granitic composition.

Dvoinoye is a low sulphidation epithermal gold-silver vein deposit. The principal vein at Dvoinoye strikes at 040° over a length of at least 800 m. Ore zone width ranges from a few metres to more than 30 m in the central shoot. The vein has been drilled over a vertical extent of about 350 m (including sills). The vein system has a steep to subvertical dip to the southeast. There is evidence that at depth the vein system may shallow in dip, from subvertical to about 70°. There are two main thick quartz veins, within a variably wide envelope of narrower veins and veinlets (stockwork zone). The central shoot represents a blowout in width where the shoot may have a pipe-like form. The bulk of the gold is in the central shoot. At depth and at the southwestern end, the mineralization forms a series of sub-parallel veins, rather than one or two wide veins. Late to post vein block faults probably disrupt vein continuity along strike, especially to the northeast where the fault-bounded granite intrusion is developed.

Mineralization is characterized by low total sulphide content, generally less than one percent, by variable but low gold:silver ratios (average 1:1), and by the presence of considerable free gold in parts of the deposit. The main ore minerals and related sulphides in the vein are native gold, freibergite, pyrite, chalcopyrite, galena, and sphalerite, with minor acanthite. Ore minerals are generally fine-grained. Gold occurs inter-grown with sulphides, free in quartz-illite aggregates, and in places as rare dendritic growth bands.

A wide variety of vein and mineralization textures are recognized, including massive vein, colloform-crustiform banded vein, breccia, and veinlet/stockwork zones. The vein mineralogy consists of quartz-chalcedony (80% to 90%), adularia (5% to 7%), carbonate (up to 5%), illite, and chlorite. The main vein displays a lateral and vertical zonation in mineralization and alteration assemblages, reflecting the evolution of the system spatially and over time. Four styles of gold mineralization have been identified: pink quartz gold; carbonate-base metal gold; chalcedony-ginguro gold silver; and green quartz breccia.

The Kupol deposit is mined by an underground mining method, long hole longitudinal retreat sublevel open stoping, also known as the Avoca method. Sills are driven on 15-metre (sublevel) spacing approximately 4.5 metres high. Longhole stopes (panels) are drilled using parallel or fan drill holes between the sublevels (approximately 11 metres). Backfill is an integral part of the production cycle of the mining method.

Dvoinoye underground mining operations have used two different mining methods, transverse longhole stoping and longitudinal longhole stoping. Transverse longhole stoping has accounted for more than 90% of the historical production, but the remaining reserves will predominantly be extracted using longitudinal longhole stoping.

The Kupol processing plant also processes ore from Dvoinoye. The ores from the two sites are processed in batches, with Dvoinoye ore typically being processed at the start of each month.

The milling process consists of primary crushing and a semi-autogenous grinding (SAG) mill / ball mill grinding circuit, and includes conventional gravity technology followed by whole ore leaching. Merrill-Crowe precipitation is used to produce gold and silver doré bars. Countercurrent decantation (CCD) wash thickeners recover soluble gold and silver, and a cyanide destruction system is used to reduce cyanide concentrations to an acceptable level for disposal. The tailings flow by gravity through a pipeline to a conventional tailings impoundment. Doré bars are shipped to the non ferrous metals plant in Krasnoyarsk. Average mill recovery, based on both Kupol and Dvoinoye ore, is 95% for gold and 85% for silver. The mill availability is 94%.

The mill is designed to process ore on ........