The Halfmile and Stratmat projectss are volcanic massive sulphide (VMS) deposits typical of the Bathurst Mining Camp (BMC). The BMC hosts 45 volcanic-sediment hosted massive sulphide deposits and 95 occurrences, including the world-class Brunswick 12 Mine. BMC deposits formed in a sediment-covered back-arc continental rift during periods when the basin was stratified with a lower anoxic water column. The basin was subsequently intensely deformed and metamorphosed during multiple collisional events related to east-dipping subduction of the basin.

The VMS deposits typically form lenses of polymetallic massive sulphide. Most deposits are zoned vertically and laterally from a high temperature, vent-proximal, copper-polonium bismuth-rich veined and brecciated core to vent-distal zinc-lead-silver-rich hydrothermal sediments. The vent complex is commonly underlain by a highly deformed sulphide stringer zone that extends hundreds of metres beneath deposits and consists of veins and impregnations of sulphides, silicates, and carbonates that cut chloritized and sericitized volcanic and sedimentary rocks.

The Stratmat claims are underlain by a magnetic northeast-southwest trending sequence of predominantly felsic volcanic rocks and lesser sedimentary rocks which are host to all massive sulphide deposits on the property. Provincial Government regional mapping projects have classified the rocks as belonging to the Flat Landing Brook formation of the Middle Ordovician Tetagouche group, which places the deposits stratigraphically above the Nepisiguit Falls formation hosted Heath Steele Minedeposits (Wilson, 1993) located 3 to 5 km to the south. Regional metamorphism is lower greenschist facies.

Coeval foliated gabbro intrusive rocks are common in the eastern half of the property and crosscut and locally assimilate portions of the favourable stratigraphy including parts of the Main Zone. Narrow, magnetic to non-magnetic discordant diabase dykes intrude western portions of the project area, with many aligned parallel to or along east- southeast-trending fault structures. A red to green unfoliated Silurian syenite dyke trends east-southeast, west of the Boundary deposit and cuts stratigraphy at least as far south as the Heath Steele ACD zones. The syenite dyke also displays a magnetic signature. A quartz-feldspar porphyry dyke, reminiscent in many respects of Heath Steele hangingwall (HW) rocks, was intersected in one hole northwest of the Boundary depositt. Distinctive intrusive rock types now number four.

Structurally, the property is highly complex with five periods of deformation being documented in the area (McBride 1976; de Roo et al. 1990; Park 1996). Tectonic thickening and repetition of the mineralized horizon has both enhanced grades and produced mineable widths of ore at the Boundary deposit and N-5 Zones. In cross section, property scale F2 folds manifest themselves as the Boundary antiform, S- 1/North zone synform and the synform/antiform fold repetition of the favourable horizon at depth, below the Boundary open pit. Best grades and widths of economic mineralization at the S-1 deposit tend to occur along the limbs of the major folds, adjacent to the closure areas. The detailed structural study conducted by Adrian Park on the N-5 and Boundary deposits has indicated extremely complex structure on the mine scale. Structures that exist at Boundary/N-5 no doubt persist elsewhere along the Horizon and complicate the rudimentary interpretations of borehole date.

Two consistent fault orientations have been documented. The Stratmat fault trends east-northeast, and overall movement appears to be dextral strike-slip, with a small dip slip component, down to the south (Park 1996). Parallel structures are interpreted at the S-1 deposit and along with Stratmat fault, are believed to be the earliest generation fault structures. A certain periodicity seems to be displayed by these faults.

Periodic east-southeast trending faults are the second and presumably younger orientation observed. Sinistral movement can be implied based upon ground geophysics (magnetics). Locally, these fault zones appear to be intruded by diabase and, west of the Boundary project, by syenite dykes. Although not believed to disrupt stratigraphy, evidence from drilling suggests that a major fault crossing the baseline at approximately 12300E appears to be a pivot or scissor fault because of dip changes immediately east and west of the structure.

The sulphide minerals consist of disseminated and massive pyrite-sphalerite-galena and chalcopyrite. The sulphide minerals are fine- to medium-grained, and are coarser than those typically found in deposits of the BMC.

Disseminated mineralization, commonly of economic grade, occurs in the phyllitic sedimentary rocks as well as in the talc layers which locally grade into massive sulphide. A layer of massive pyrite-chalcopyrite, typically less than 1 m thick, occurs locally on the stratigraphic footwall side of the economic mineralization.

Stratigraphic relationships are based on observations of drill and rock exposures. The copper-rich layer may be in contact with, or grade into pyrite-poor massive sphalerite galena ore that locally is up to a few meters thick (grades average 5 to 15% lead and 15 to 35% zinc). Gangue minerals include muscovite, talc, chlorite, quartz, and carbonates. Many of the copper-rich and lead-zinc-rich massive sulphide layers are separated by talcose or phyllitic zones that commonly carry disseminated sulphide mineralization. Calcite is the most common carbonate, but ferroan dolomite and siderite also are present.

At Stratmat, RoM material will be mined by underground mining, too, similar to Halfmile underground mining except there is no PPCF/MCF mining method employed. RoM materials will be directly hauled by 45-tonne capacity underground trucks to Stratmat DMS plant for waste separation.

There will be two independent ramp systems to access Stratmat underground mineralization. The Main ramp system will be used to access the S1 (Shallow and Deep), S0, and S5 zones (main production system); and the Main zone ramp will be used to access the Main zone underground mineralization (supplement production system).

Backfill will be first sourced from development waste rock, supplemented by back trucked Stratmat DMS plant separated waste.

Ventilation is designed at 189 cms (400,000 cfm) for a production rate of 1,400 t/d for the main production system, providing an estimated 14% contingency. Intake will be through the Main ramp and a 3.6 m diameter of raisebored FAR, exhaust will be through a 4.5 m diameter of raisebored RAR.

Ventilation is designed at 42 cms (90,000 cfm) for the supplement production system. Intake will be through the Main zone ramp, exhaust will be through a 2.4 m diameter of raisebored RAR.

Underground dewatering strategy is similar to the Halfmile underground dewatering system.

Due to the complex geometry and variability in strike and dip, the development of a tool box of mining methods is recommended in order to maximize extraction of the Stratmat project.

The most of the S1 Deep zone will tend to use transverse Sublevel open stoping (SLOS) supplemented with longitudinal Sublevel Retreat (SLR) open stope mining method when mineralization width is less than 8–12 m. All other zones will be mining using SLR. A small portion of mineralization can be mined using Uppers such as relatively isolated stope and extremity of strike length. A sub-level spacing of 20 m has been selected for these zones. Backfill for the transverse stopes would be cemented rock fill (CRF) for primary stopes and RF and/or CRF for secondary stopes. Backfill for the longitudinal retreat stopes would be a mix of CRF with RF.

A modified Avoca method could also be utilized in some areas of the Main zone and S1 Shallow zone, instead of the more typical SLR. Modified Avoca is an alternative of longitudinal retreat mining method, which has been successfully implemented in Trevali’s Caribou and Santander operations.

Halfmile Stratmat Concentrator includes crushing and DMS circuits.

In the current Preliminary Economic Assessment for the Halfmile-Stratmat Massive Sulphide Zinc-Lead-Silver Integrated Project has been assumed that primary crushing, secondary crushing and screening will be contracted out. The crushed product will be fed to a covered stockpile with a live content of 4,000 tonnes and the DMS plant will be fed using two apron feeders in a tunnel under the stockpile at 175 tonnes per hour. The dense media process is expected to reject 22% of the mass of RoM material in a reject which will be suitable for producing backfill with the addition of the required amount of cement. As only the +3 mm fraction of the RoM material can be upgraded, the -3 mm fraction will be screened out on a wet screen, thickened and the thickener underflow pumped to the ball mill discharge pump box or to a lagoon if the DMS plant is operating and the main plant is down. DMS upgraded material will be conveyed to a second stockpile with a live content of 3,000 tonnes.

Design feed tonnage to the grinding circuit is 145 tonnes per hour. The BAG mill will operate in closed circuit with a vibrating screen recycling the +5 mm fraction back to the BAG mill. Screen undersize will flow to a secondary ball mill which will operate in closed circuit with 15-inch diameter cyclones and will grind the material to a P80 of 72 microns.

The PEA is based on the construction of a new concentrator at the Stratmat site to process both the Stratmat mineralization and the Halfmile mineralization which will be trucked to the Stratmat site. The new concentrator will have a capacity of 3,000 t/d and employ conventional differential flotation technology to produce three saleable metal concentrates of zinc, lead, and copper. For both the metallurgical performance and the operating costs of a new concentrator, reference has been made to the current operations of Trevali at the nearby Caribou Mine.

The RoM production will initially be subjected to primary and secondary crushing at the Stratmat mine site to reduce the rock size to a suitable feed for a dense media separation plant (DMS). This operation will reject barren material from the +3 mm size from the mill feed effectively increasing the mill head grade and reducing the overall operating costs of the concentrator. A Barely Autogenous Grinding (BAG) mill will be us ........