The Pogo is in the Tintina Mineral Belt, which is a 200 km-wide, 1,200 km-long arc, broadly bounded by the Tintina-Kaltag fault systems to the north and the Denali-Fairwell fault systems to the south. The region contains numerous economic deposits of gold in addition to copper, lead, zinc, silver and tungsten deposits.

The lithological units in the Pogo deposit area are dominantly high-grade metamorphic rocks intruded by later felsic to intermediate intrusive units. Key metamorphic rocks include biotite feldspar gneiss, augen gneiss and mafic schist derived from both sedimentary and igneous protoliths. Metamorphic mineral assemblages observed consist of quartz, feldspar, biotite, chlorite, muscovite, sillimanite, andalusite and garnet. The 50km long Goodpaster batholith (granite tonalite-diorite) is the dominant intrusive complex in the district. Locally small felsic to intermediate stocks and dykes are present.

The principal mineralisation is hosted in biotite-quartz-feldspar paragneiss and orthogneiss, although all other lithologies are cut. Where the veins cross intrusives, they tend to split and become stockwork zones.

Gold at Pogo is predominantly hosted within laminated quartz veins ranging in thickness from <0.5m to >10m. Mineralised veins contain around 3% sulphides (arsenopyrite, pyrite, pyrrhotite, loellingite, chalcopyrite, bismuthinite, sphalerite, galena, molybdenite, tetradymite, maldonite) and a variety of Bi-Pb-Ag sulphosalts.< ........

Since 2018, Pogo has transitioned from primarily cut and fill to mostly longhole stoping with paste filling. Northern Star has also transitioned to high-speed development using jumbos to bolt-mesh-bore which, until recently, was not common practice in North America.

Four portals are in use which provide access to the various underground mining block areas. Mining block areas are named Liese, East Deep, North Zone, X vein, South Pogo and Fun Zone. Portals are named by their approximate elevation on the topography.

The 1525 portal driven in 1996 is the original exploration drive that eventually provided access to the first Liese vein bulk sampling.

After planning and permitting processes were completed the 1875 portal and associated ore body ramp development was constructed in 2005. The 1875 provided access to Liese veins and was driven to connect with concurrent expanded development from the 1525 decline.

The 1650 portal is located a ½ mile down the drainage from 1875 and was driven to support waste haul and exhaust air routing out of mine during development. After major development in the 1650 area was completed in 2006, the 1650 decline was then outfitted with a conveyor to supply mill from a mine ore bin. The main paste backfill system supply pipe from mill to mine was also installed down the 1650 decline.

The 2150 portal and decline are located approximately 1/3 -mile northwest of the 1875 portal area. The 2150 declin ........

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