Homestake Ridge lies within the highly prolific Iskut-Stewart-Kitsault Belt that is host to several precious and base metal mineral deposits. Homestake Ridge has over 80 mineral occurrences on the Homestake Ridge related in the emplacement of intrusive stocks and felsic domes into the volcanic sedimentary host rocks.

Diverse mineralization styles on the Homestake Ridge include stratabound sulphide zones, stratabound silica-rich zones, sulphide veins, and disseminated or stockwork sulphides.

Mineralization displays characteristics of both epithermal gold and VMS deposition. Stratabound and vein (or replacement) mineralization is present that contains values in Ag, As, Au, Cu, Hg, Pb, Sb and Zn. The property geology is considered to be favourable for the discovery of “Subaqueous Hot Spring Au-Ag” or “Low Sulphidation Epithermal Au-Ag” type deposits.

The main zones of the Homestake Ridge deposit are the Homestake Main, Homestake Silver, and Silver Reef. The Homestake Main is the more copper-rich of the zones, with both gold-rich and silver-rich variants and an apparent trend of increasing copper grade with depth. The Homestake Silver zone is primarily silver with elevated lead values, and South Reef is essentially high-grade gold, with minor copper and lead.

The Homestake deposits are commonly vertically zoned from a base metal poor Au-Ag-rich top to an Ag-rich base metal zone over a vertical range of 250 m to 350 m. The silver-galena-sphalerite veins of the Homestake Silver Zone exhibit many of these features.

Homestake Main Deposit
The Homestake Main deposit consists of a series of silica to silica-carbonate-chlorite altered lenses and hydrothermal breccias, which have a northwest strike and dip moderately northeast at slightly steeper than the topographic dip-slope. Gold and silver mineralization occurs with pyrite, chalcopyrite, and lesser galena and sphalerite in stronger areas of silica alteration or hydrothermal brecciation within zones of sericite-pyrite altered feldspar-hornblende phyric volcanic rocks. Only along the southwestern flank of the Homestake Main deposit does lower grade gold mineralization penetrate up into the overlying package of basinal filling volcano-sedimentary and andesitic rocks which comprise the “hanging wall” sequence. Native gold along with pyrargyrite and acanthite have been observed hosted within quartz veins and quartz-carbonate hydrothermal breccias in drill core.

The Homestake Main deposit as currently known is about 700 m long and has been traced downdip by drilling for a distance of approximately 500 m. At the surface, the northwestern extent of the mineralization is obscured by a glacier; while to the southeast surface geochemistry indicates that the zone continues towards the Homestake Silver deposit 700 m to the southeast. Widths of the Homestake Main Zone vary up to about 60 m (approximate true width) and are defined by assay grades due to the diffuse nature of the mineralization.

Grades for gold typically range from 0.1 g/t Au to 2 g/t Au with some intercepts measuring into the hundreds of grams per tonne and averaged at 7.75 g/t Au. Silver grades are generally in the 1.0 g/t Ag to 100 g/t Ag range but can be as high as hundreds and even thousands of grams per tonne. The average silver grade in the HM is 68.6 g/t Ag. Copper grades vary from parts per million to several percent, with mean grades observed to increase significantly with depth.

Homestake Silver Deposit
Homestake Silver Deposit is located 300 m to the southeast of the Homestake Main zone, the Homestake Silver deposit is comprised of a series of northwest trending, vertically to sub-vertically dipping hydrothermal breccias. Mineralization occurs as galena, sphalerite and silver in contrast to the gold enriched chalcopyrite seen the Homestake Main deposit. Modelling indicates that the Homestake Silver deposit can be traced over 700 m strike and 550 m down dip.

The Homestake Silver zone comprises a cluster of parallel structurally controlled zones, striking approximately 140° with near-vertical dips. The individual sub-zones in the Homestake Silver zone are narrower than the Homestake Main zones on average, with true thickness rarely exciding three metres. The Homestake Silver zone has been traced by drilling for a total vertical extent of approximately 600 m, along a strike length measuring just under 800 m.

Silver grades at Homestake Silver average 154 g/t Ag, approximately double that of the HM (68.6 g/t Ag) and 26 times that of SR (5.8 g/t Ag). Gold grades at Homestake Silver typically range up to several g/t Au and averaged 3.5 g/t Au in the samples contained within the interpreted zone boundaries. Copper content is comparatively low, however, geochemically significant, and generally measures between 10 ppm Cu and 500 ppm Cu. There are elevated levels of lead and zinc, typically measuring in the 10 ppm to 1,000 ppm range, with some intercepts assaying as high as several percent lead and/or zinc.

South Reef Zone
The South Reef deposit is located approximately 800 m to the south-southwest of the Homestake Silver deposit. Gold mineralization is variably associated with strong quartz-chlorite alteration, pyrite and minor base metal sulphides interspersed with intervals of sericite and pyrite alteration in two en-echelon, northwest-trending sub-vertical mineral zones that can be traced with drilling for over 250 m strike-length and 250 m dip. Several base-metal enriched intercepts are identified up-section from the gold-enriched zone but have yet to be fully defined by drilling.

The South Reef zone is comprised of two narrow sub-parallel tabular bodies which strike at approximately 120° to 130° and dip 70°NE to 80°NE. To date, only twelve holes have intersected significant mineralization, as such characterization of the structure and grades is preliminary. The zones measure one metre to three metres in thickness and have been traced for approximately 300 m vertically and 400 m along strike. Silver grades at South Reef average 5.8 g/t Ag in the vein samples. This is offset by high gold values, which average 5.9 g/t Au.

All three zones have elevated arsenic and antimony contents, typically averaging in the tens to low hundreds of parts per million.

The principal mining method utilized in the Deswik Stope Optimizer (DSO) runs was longhole stoping (LHOS) based on a 20 m sublevel interval. Each sublevel consists of an ore drive off a spiral ramp connecting to the level access. A minimum mining width of 2.5 m was selected to allow for mechanized mining.

The main deliverable from the Deswik stope optimizer was a life of mine production schedule based on a combined 900 tpd mill feed rate. This yields a mine life of just under 13 years.

The total mill feed includes roughly 0.34 M Indicated tonnes, 2.52 M Inferred tonnes, 0.56 M dilution tonnes. Just under 50 percent of the mineralized tonnes come from the Homestake Main deposit. The Silver deposit contributes another 41 percent, and the South Reef contributes the final 11 percent.

The resulting mine production schedule consists of 2.87 M stope tonnes and 0.55 M mineralized development tonnes for a total of 3.42 Mt grading 5.41 gpt Au, 84.31 gpt Ag, 0.13 percent Cu and 0.12 percent Pb.

The mine development will be accomplished by mechanized trackless equipment. The PEA mine plan includes a combined 10 km of ramps in the three deposits, 12 km of level access, and another 22 km of ore drives primarily in mineralized material.

The primary mining method of longhole retreat stoping will employ the use of uncemented rockfill to backfill the mine voids as the stope advances. Since the mine will advance by overhand methods, the backfill will used as the working floor for mining the stope on the sublevel above.

The mine is expected to consume roughly 1.2 million m3 of rockfill over the life of the mine, or roughly 275,000 tpa.

Processing of Homestake Ridge mineralization will be complicated by the difference in metal contents across the 3 principal deposits. The Homestake Main mineralization is high in copper, low in lead, and moderate in zinc. The Homestake Silver and South Reef mineralization has low copper grades. Homestake Silver has relatively low gold grades but high lead, zinc, and silver grades. South Reef is essentially just gold with a minor amount of copper.

Different processing streams are required to liberate the metals from these deposits. Rather than blending into one process stream, the optimal process strategy appears to be campaign mining and processing: Homestake Main would be exploited first to produce a single copper concentrate; then mining and processing at Homestake Silver to produce a single lead/zinc concentrate. The changeover from the Main to Silver deposits will not require any equipment changes in the grinding circuit, but it may require a change to the grind size, an ........