The mineralization at the Arctic Deposit and at several other known occurrences within the Ambler Sequence stratigraphy of the Ambler District, consists of Devonian age, polymetallic (zinc-copper-lead-silver-gold) VMS-like occurrences. VMS deposits are formed by and associated with sub-marine volcanic related hydrothermal events. These events are related to spreading centres such as fore arc, back arc or mid-ocean ridges. VMS deposits are often stratiform accumulations of sulphide minerals that precipitate from hydrothermal fluids on or below the seafloor. These deposits are found in association with volcanic, volcaniclastic and/or siliciclastic rocks. They are classified by their depositional environment and associated proportions of mafic and/or felsic igneous rocks to sedimentary rocks.

In the Ambler District, VMS-like mineralization occurs in the Ambler Sequence schists over a strike length of approximately 110 km. These deposits are hosted in volcaniclastic, siliciclastic and calcareous metasedimentary rocks interlayered with mafic and felsic metavolcanic rocks. Sulphide mineralization occurs above the mafic metavolcanic rocks but below the Button schist, a distinctive district wide felsic unit characterized by large albite porphyroblasts after relic phenocrysts. The presence of the mafic and felsic metavolcanic units is used as evidence to suggest formation in a riftrelated environment, possibly proximal to a continental margin.

A sulphide-smoker occurrence has been tentatively identified near Dead Creek northwest of the Arctic Deposit and suggests local hydrothermal venting during deposition. However, the lack of stockworks and stringer type mineralization at the Arctic Deposit suggest that the deposit may not be a proximal vent type VMS. Although the deposit is stratiform in nature, it exhibits characteristics and textures common to replacement-style mineralization. At least some of the mineralization may have formed as a diagenetic replacement.

At Arctic, sulphides occur as semi-massive (30 to 50% sulphide) to massive (greater than 50% sulphide) layers, typically dominated by pyrite with substantial disseminated sphalerite and chalcopyrite and trace amounts of galena and tetrahedrite. The Arctic Deposit sulphide accumulation is thought to be stratigraphically correlative to those seen at the Dead Creek and Sunshine deposits up to 12 km to the west.

There is also an occurrence of epithermal discordant vein and fracture hosted base metal (lead-zinc-copper) mineralization with significant fluorite mineralization identified at the Red prospect in the Kogoluktuk Valley, east of the Arctic Deposit. Although not yet fully understood, the genesis of this occurrence is considered to be related to the regional system that formed the VMS deposits in the Ambler District.

Mineralization occurs as stratiform SMS to MS beds within primarily graphitic chlorite schists and fine-grained quartz sandstones. The sulphide beds average 4 m in thickness but vary from less than 1 m up to as much as 18 m in thickness. The bulk of the mineralization is within five modelled zones lying along the upper and lower limbs of the Arctic isoclinal anticline. All of the zones are within an area of roughly 1 km2 with mineralization extending to a depth of approximately 250 m below the surface. There are five zones of MS and SMS that occur at specific pseudo-stratigraphic levels which make up the bulk of the mineral resources. The other three zones also occur at specific pseudo-stratigraphic levels, but are too discontinuous to confidently model as resources.

Unlike more typical VMS deposits, mineralization is not characterized by steep metal zonation or massive pyritic zones. Mineralization is dominantly sheet-like zones of base metal sulphides with variable pyrite and only minor zonation usually on an extremely small scale.

Mineralization is predominately coarse-grained sulphides consisting mainly of chalcopyrite, sphalerite, galena, tetrahedrite, arsenopyrite, pyrite and pyrrhotite. Trace amounts of electrum and enargite are also present. Gangue minerals associated with the mineralized horizons include quartz, barite, white mica, black chlorite, talc, calcite, dolomite and cymrite.

The mine will utilize a conventional truck-and shovel fleet and the proposed open pit operations will provide process plant feed at a nominal rate of 10,000 t/d. The pit design incorporates a bench height of 5 m and an inter-ramp angle of 45°. Pit optimization and design results are based on scoping level geotechnical and operational information.

Due to operational and geometric constraints, the mine will require a ramp-up period of three years before achieving full mill capacity. The mining schedule does not currently consider a low-grade stockpiling option but this can be assessed in more detail in future studies.

A 10,000 t/d process plant has been designed to process the massive and semi-massive sulphide mineralization of the Arctic Property. The main economic elements found in the deposit are copper, zinc, lead, and associated gold and silver. The process plant will operate two shifts per day, 365 d/a with an overall plant availability of 92%. The process plant will produce three concentrates: 1) copper concentrate, 2) zinc concentrate, and 3) lead concentrate. Gold and silver are expected to be payable at a smelter and are recovered in both the copper and lead concentrates. The process plant feed will be supplied from the Arctic open pit mine.

The crushed material will be ground by two stages of grinding, consisting of one SAG mill and one ball mill in closed circuit with hydrocyclones (SAB circuit). The hydrocyclone overflow with a grind size of approximately 80% passing 70 µm will first undergo pre-talc flotation, and then be processed by conventional bulk flotation (to recover ........