Name: Pogo mine.

Location: The project is located 145 km south-east of Fairbanks, in the US state of Alaska, in the Tintina gold province.

Mine Owner/s: Northern Star Resources.

Brief History: In 1981, WGM, financed by Phillips Petroleum, conducted a stream sediment and pan concentrate sampling programme in the Goodpaster river area, identifying Pogo Creek and, to a lesser extent, Liese Creek as anomalous for gold, arsenic and tungsten. Follow-up work confirmed this anomaly and identified mineralised quartz float, but no further work was conducted for nearly ten years.

In 1997, Sumitomo Metal Mining and Teck Resources signed a letter of intent whereby Teck could obtain a 40% interest in the property.

Production at the mine started in 2006.

In mid-2009, Sumitomo agreed to buy Teck’s 40% stake for $245-million becoming the operator of the Pogo mine.

In mid-2018, Northern Star Resources agreed to buy the Pogo mine from Sumitomo for $260-million, becoming the sole owner and operator of the mine on September 28, 2018.

Brief Description: The Pogo mine comprises the Liese, East Deep, North Zone, X Vein and Fun Zone mining block areas.

Primary Metals: Gold.

Secondary Metals: Arsenic and tungsten.

Geology/Mineralisation: The Pogo gold deposit comprises several massive auriferous quartz +/- sulphide veins hosted in a sequence of amphibolite-grade, paragneiss and orthogneiss of Proterozoic to mid-Paleozoic age. Mid-Cretaceous age granitic plutons and dikes intrude the gneisses, which, in turn, are cut by the veins. The Proterozoic gneiss and Cretaceous granitoid sequence are part of the Yukon-Tanana terrain, a goldbelt extending from Fairbanks into the historic gold mining areas of the Yukon territory.

The age of the gold mineralisation is about 104-million years (Cretaceous) and is controlled by a low-angle regional shear and high-angle fault structures, which are interpreted as the fluid conduits for hydrothermal fluids. The field has undergone regional metamorphism, peaking at 110-million years, resulting in moderate folding and foliation of the metamorphic host rocks. Retrograde metamorphism resulted in cooling, which transformed the ductile deformation of the metamorphic fabric to brittle (semiductile to brittle) deformation resulting in a low-angle shear across the region. Gold in the quartz veins is characterised as Pogo-type mineralisation and occurs as inclusions in arsenopyrite, inclusions in quartz, composite intergrowths with bismuth/tellurium/sulphur minerals in quartz and invisible gold inclusions to solid-solution atomically bounded in loellingite, coupled with low arsenic arsenopyrite.

The ultimate source of the hydrothermal fluids responsible for the Pogo deposit remains unknown. The intrusion related and orogenic gold models have characteristics that support the evolution of the Pogo deposit. However, currently, the IRG model best fits current observations and measurements.

Reserves: Not stated.

Resources: Total mineral resources as at June 30, 2018, were estimated at 8.76-million tonnes grading 14.7 g/t gold.

Mining Method: Mining methods at the Pogo Mine vary owing to great variability in vein thickness, dip, grade and continuity. Ore is commonly mined in vertically offset horizontal cuts with longhole stoping in between.

Vein shapes may contain splits with varying thickness and have a dip of near flat to vertical (90 º) . Veins that are more vertical are mined in longhole panels after the upper and lower access drives are mined. For ore structures that dip from near flat to 45 º, ore is mined using blind hole slashing methods that drill up or sideways into the exposed vein from the ground supported initial cut. Stopes may also be mined in adjoining strips that are tight paste filled, with a directly adjacent parallel strip being mined after paste cure time.

Major Infrastructure and Equipment: Three access portals are in use that provide underground access to the various underground mining block areas, with the major underground mining equipment comprising development and production drills, haul trucks, loaders, explosive loading units and service vehicles.

The processing circuit involves gravity concentration, gold and sulphide flotation, and leaching and adsorption of gold with a leach/carbon-in-pulp unit operation.

The Pogo operation maintains one dry stack tailings facility that has been in operation since 2006.

Prospects: The existing resource base for Pogo provides a strong platform for growth. In addition to existing resources, exploration drilling continues to demonstrate the long-term system-wide potential of outlying prospects on the Pogo claims.

Contact Details:
Northern Star Resources
Tel +61 8 6188 2100
Fax +61 8 6188 2111
Email info@nsrltd.com
Website https://www.nsrltd.com