Main Zone
The Main Zone is a structurally controlled orogenic gold deposit characterized by precious metals enhanced sulphides containing significant gold, silver, lead and zinc. The deposit has a very predictable geometry. The zone is sheet-like or tabular with an average dip of about 56° to the northeast. The zone of sheeted massive and stringer sulphides having an average true width of 2.5 metres but can reach 15 metres in true thickness. The continuity of the zone is interrupted in a few places where it pinches out completely within narrow stretches. Exploration has confirmed persistent vertical and horizontal continuity of the Main Zone. On surface, a strike trace of at least 3.3 km has been defined. In addition, it is speculated that the Main Zone is linked to the Roseberry Prospect and also to the former Mastodon Mine, which would suggest a collective potential strike length of nine kilometres. The deposit has been traced 1,500 metres along strike and 800 metres down dip by underground drilling. Within this, it is exposed for 850 metres along strike by underground drifting along the 830 Level. Extensive drilling has indicated a traceable continuous plane with no significant fault offsets, cut-offs or fault drags zones, and there is possibly an element of improved grade in en-echelon series of northwest plunging lenses that strengthen with depth.

The Main Zone is composed of closely spaced bands of massive sulphides that frequently coalesce at its widest parts. Individual bands, that are generally tabular, may die out along strike over tens of metres but appear to resume in an adjacent band. Individual massive sulphide bands frequently range from five centimetres to one metre thick. Sulphide minerals include pyrite, pyrrhotite, gold- bearing arsenopyrite, iron-rich sphalerite (blackjack), galena, tetrahedrite and trace chalcopyrite. There are also traces of silver-lead-antimony (Ag-Pb-Sb) and lead-antimony sulphosalts. The banding ranges from predominantly arsenopyrite (high gold), to mixed arsenopyrite and massive sulphides, to massive sphalerite with no arsenic present. Where the mineralization narrows, it is almost completely composed of arsenopyrite. Mineralization widens and sulphide assemblage is more diverse where it is in contact with, or completely enclosed by, limestone. Between mineralized bands, the host rock has been altered (sericite-quartz) and contains disseminated mineralization or thin massive to stringer sulphide streaks.

Three distinct types of mineralization have been noted:

• Type I: mineralization is comprised of massive bands, lenses and stringers of sulphides in a sericitic shear zone. Sulphides consist of medium to coarse grained pyrite, variously grain sized arsenopyrite, and fine-grained fracture-filled sphalerite and galena. Some coarse-grained pyrite and arsenopyrite display a brecciated texture.
• Type II: mineralization is characterized by “milled” massive sulphide texture consisting of fine to coarse-grained, rounded to sub-rounded pyrite, arsenopyrite, quartz, and wall rock clasts in a very fine-grained sulphide matrix. The matrix is composed of fine-grained pyrite, arsenopyrite, sphalerite, galena and quartz. Clasts derived from the host rock such as phyllite and schist contain sulphide stringers, which in part may represent Type I form of mineralization. This milled feature is interpreted as a mylonite texture developed within a shear zone. Milled sulphides carry high values of gold, silver, lead and zinc, and elevated mercury and antimony.
• Type III: mineralization consists of narrow stringers and fine to medium-grained disseminations of principally sphalerite, with lesser amounts of galena and pyrite and very little arsenopyrite. Sphalerite is red to honey yellow in color and appears to replace limestone. Although Type III mineralization can reach widths of 6-10 metres, it appears to have limited extent both along the strike and vertically.

The Main Zone is sericite, carbonaceous and chlorite altered. The chloritic and sericitic phyllites of the wallrock are gradational in composition laterally and vertically making subdivision difficult.

Principal gangue minerals to the Main Zone include quartz, calcite, siderite, sericite and chlorite.

Yellowjacket Zone
The Yellowjacket Zone does not outcrop and as such was only discovered in 1991, late in the exploration history of the evaluation of the Main Zone. The Yellowjacket Zone is thought to be a stratabound carbonate hosted, lead-zinc-silver deposit but careful examination of the 2012 drill core of the Yellowjacket strongly supports a structurally controlled replacement model. Mineralization occurs at contacts between limestone and meta-volcanics and, because there are frequent alternations or interbedding of these two lithologies in this area, the Yellowjacket Zone is composed of multiple subzones.

The Yellowjacket Zone is generally sub-parallel to the Main Zone and is located approximately 30 metres into the hanging wall rock of the Main Zone. The lead-zinc-silver mineralization is confined to multiple discrete zones hosted in siliceous carbonate units. The Yellowjacket Zone does not outcrop and is defined only by drilling. Limited drilling (42 holes) has traced the deposit along strike for 500 metres where the Yellowjacket Zone Mineral Resource is defined. The deposit appears to rake to the southeast at 30°. The Yellowjacket Zone remains open beyond the limits of the Mineral Resource, both laterally to the northwest and at depth. Three drill holes from one collar set-up 300 metres northwest, picked up Yellowjacket Zone mineralization. A 2014 soil geochemical survey indicated elevated Zn-Pb-Ag values along trend of the zone for 800 metres further northwest of the Mineral Resource area.

The Yellowjacket Zone has no arsenic content and little gold. The mineralization is composed of disseminated and patchy massive zinc-rich honey-coloured (yellowjack) and red coloured sphalerite with minor medium-grained disseminated and hairline stringers of galena with elevated silver values. Other minerals include calcite, silica and minor sericite and siderite. Texturally, the mineralization can be foliated and/or laminated with sphalerite and galena running along cleavage surfaces. Other textures include brecciated or lacework patterns. Dolomite sections show discontinuous banding and are usually lower in grade.

The carbonate units hosting the Yellowjacket Zone may be occurring in the hinge of a recumbent isoclinal fold, fringed by phyllite and quartzite. The mineralization appears to thicken in the apparent fold hinge where darker coloured sphalerite and coarser and more abundant galena occurs. The Yellowjacket Zone is intensely silicified. Sericite has also been observed in core samples. Silicification also appears to intensify towards the apparent fold hinge. Fluorite is common in most mineralized sections, particularly near higher grade sections. Pyrite and pyrrhotite are present in low amounts.

The potentially mineable portion of the Revel Ridge Yellowjacket and Main Zone mineral resources extends along the strike length of the deposit for over 1 km, and over 800 m vertically from the 1310 Level to the 510 Level.

Currently, there is an exploration drift on the 830 Level, accessed by the 832 adit portal. There are also several other adits, none of which are anticipated to be used for mine traffic during mining operations but can be reopened and reinforced to provide secondary egress as required. Portions of the mine plan, above and below the 830 Level, are referred to as the upper and lower mine, respectively.

The stope shapes used were 20 m in height, 20 m in length and had a minimum stope design width of 2.5 m. The stope shapes also include an allowance for overbreak and include internal waste dilution.

The conceptual production mine plan produces an average 2,300 t/d of process feed for almost twelve years (11.96 years).

The first nine (9) years of the project focusses solely on mining the Main Zone, while years ten through twelve incorporate the mining of Yellowjacket Zone as well. The mining rate of 2,300 tonnes per day amounts to 839,500 tonnes per year, for a total of 10,039,384 tonnes over the 12-year mine life. The process feed from the Main Zone amounts to 9,392,872 tonnes, while the remaining 646,512 tonnes of process feed comes from Yellowjacket Zone.

The mine plan mines on 40 different levels from the 510m level to the 1310m level which extends up to the 1330m elevation. The level spacing is 20m vertically.

Additional input parameters for the stope optimizer were based upon the assertion that stope heights are confined to 20-m sublevels, with 5-m high sill development on each level. Stope widths were allowed to follow the width of the vein to a minimum of 2.5 m. Dilution is accounted for in the stope optimization process, and varies with the width of the vein.

Longitudinally oriented stopes are planned, with cemented tailings and development waste as backfill. Mine sublevels, where drilling, blasting, and mucking will take place, are vertically spaced 20m apart, with main haulage levels at 60m vertical intervals. Sublevels are conservatively spaced to allow for gravity flow of broken material, given the intermediate dip of the mineralization(about 55o, or less). Stopes are also designed to aid in gravity flow. On the haulage levels, crosscuts will be driven every 40m along strike to access the muck.

To the extent possible, mining will progress in an overhand fashion (drilling uppers only) with the lower blocks being mined first and progressively higher blocks being mined subsequently. The stoping cycle will include long-hole drilling, blasting, mucking, and backfilling.

Backfill plant construction will commence at the beginning of the first year, most likely on the 830 level. Both development waste and cemented backfill will be used. Floats from the HMS plant will also be available for use in backfill.

PAG waste will report directly to the PAG Waste Pile and will not be used for backfillingin the upper mine.Where the schedule permits, some PAG waste may be stowed in areas of the lower mine that will be permanently flooded following mine closure.

Combined sill development and stoping are expected to provide 2,300 t/d of mill feed. Over the life-of-mine, sill development will contribute about 2.30 million tonnes and stoping will contribute about 7.74 million tonnes for a combined total of 10.04 million tonnes.

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The base case flowsheet for the Main Zone mineralization comprises primary and secondary crushing, pre-concentration using heavy media separation (HMS), grinding, gravity separation, sequential flotation of lead, zinc and gold rich sulphide concentrates, concentrate dewatering, and tailings disposal. The base case also includes the pressure oxidation of the gold rich sulphide concentrate and subsequent gold recovery using carbon-in-leach (CIL)technology, while the alternative case assumes that the gold rich sulphide concentrate is sold to an international smelter/refinery.

Heavy Media Separation
The heavy medium separation (HMS) circuit will be utilized to upgrade the mineralization from the Main Zone by the selective removal of crushed non-sulphide, relatively light, gangue material. Testwork has suggested that typically about 28% of the feed can be removed as waste with minimal loss of valuable metals. For the PEA a modular 100 t/h HMS cyclone plant with a SG cut-poin ........