Gold mineralization at the Holt and Holloway Mines is associated with replacement carbonate-pyrite-albite-quartz alteration that overprints mafic volcanic rocks in, and adjacent to, D3-D4 high strain zones.

At the Holt Mine, mineralized zones that have been historically mined are hosted by the McDermott shear zone, a 10 m to 50 m wide south-southeast dipping carbonate-sericite chlorite ± albite altered ductile D3-D4 shear zone, which is hosted by otherwise massive, and generally low strain mafic volcanic rocks. The McDermott shear zone has been traced laterally for approximately 10 km along strike, joining the Destor- Porcupine corridor to the northeast. It has been traced by drilling at least eight kilometres west of the Holt Mine headframe. The shear zone may be localized along an older D2 thrust plane that has structurally emplaced lenses of fine-grained clastic sedimentary units along it. Principal mineralized zones that have been mined to date along the structure include the South, C-104, McDermott, Worvest/Three Star, Mattawasaga, and C-97 zones, which occur over a strike length of three kilometres and have been mined to depths of over one kilometre below surface. More recently, the C-103, Zone 4 and Zone 6 gold mineralization has been identified along these geologic structures and are host to the bulk of the existing gold mineralization. All but the South Zone and Zone 4 occur in steeply south dipping sections of the shear zone. The South Zone and Zone 4 occur where the shear zone rolls to moderate to shallow southerly dips (Rhys, 2005a). Prominent within the Holt Mine geology are two northeast to east-northeast trending brittle faults: the Ghostmount and the McKenna. Although once interpreted as mineralization controlling structures, they offset mineralization and are in fact the youngest structural elements in the region (Rhys, 2005a).

Mineralization frequently occurs within the upper (hanging-wall/south) portions of the McDermott shear zone, often in areas where the structure defined by its carbonate- sericite-quartz altered high strain zone widens from a thickness of generally less than 10 m to locally greater than 50 m wide. The widening may in part be controlled by the interaction of the shear zone with lenses of carbonaceous sedimentary rocks in its footwall. Mineralization occurs in massive to banded quartz-carbonate-pyrite-albite alteration that occurs within the McDermott shear zone and may extend a short distance into adjacent, unfoliated, massive mafic volcanics. Diffuse quartz veinlet networks and matrix are commonly developed, locally imparting breccia textures in sheared rocks. The apparent overprinting of foliation by alteration, and rotation of shear zone fabrics in breccia fragments, collectively suggest that mineralization overprints portions of the McDermott shear zone, and that it formed during or after most shear zone fabric development. An early phase of hematite-bearing carbonate- albite-quartz alteration is often preserved as lenses and domains within and adjacent to the Holt Mine mineralized zones (Rhys, 2005a).

Zones 4, 6 and C-103 at the Holt Mine have a well established higher grade gold zone (i.e., more than 3 g/t Au) related to a zone of more intense alteration, including sericite, chlorite, hematite and silicification, and elevated concentrations of sulphides within an overall lower grade envelope. This higher grade zone, typically three to five metres thick, is almost exclusively located along the hanging wall of the deposit, against the Ghostmount fault or any associated fault splay. The zones typically extend over 100 m along strike and 100 m down dip.

Native gold in mineralized zones at Holt occurs as fine grains spatially associated with pyrite, in fractures, on grain boundaries, or encapsulated in pyrite grains. Microscopically, gold grain distribution can be clustered; however, assays do not reveal erratic or “nuggety” gold concentrations. Gold values in mineralized zones die out laterally, over several metres within the envelope of altered rock. There is generally a fairly sharp boundary on the hanging-wall side, but a more gradational die off of values on the footwall side. This is particularly evident in the Zone 4 and C-103 and less evident in Zone 6 where the contacts of the mineralization are generally sharp with the surrounding mafic volcanic rocks.

The primary stoping method at the Holt Mine is mechanised long hole drilling and blasting within the mining blocks with rail transport to the shaft ore passes. The spacing between sublevels for long hole stoping varies between 20 m and 17 m, depending on the dip of the ore. Mechanized long hole stoping is planned to be used in all zones at the Holt mine. “Drift and pillar” stoping may be needed in some areas where the ore is too shallow and not amenable to long hole methods. Drilling is performed with tophammer drills, with hole sizes ranging from 64 mm to 76 mm in diameter.

The Tousignant Zone is planned to be mined with modified room and pillar.

Zone 4 is accessed by mechanised equipment via ramps and sublevels connected to two main rail haulage levels 925 and 1075. Zone 4 is divided into two mining blocks: the upper mining block represents the stopes reporting to the 925 haulage level and the lower mining block represents the stopes reporting to the 1075 haulage level. The use of both haulage levels provides increased flexibility to the overall Holt mine plan.

The mine extraction sequence for Zone 4 is using a primary-secondary stoping arrangement with cemented rock fill being used in the primary stopes. Strike length is set at 15 m for the primary stopes and 20 m for the secondary stopes. Sublevels in Zone 4 are spaced 17 m apart due to the shallow dipping nature of the ore within the zone. The current mine plan includes stopes being mined using up holes, with the remainder of the stopes being mined using down holes. This method of combining up and down hole configurations helps minimize hole length and increases accuracy of hole drilling.

Zone 6 is planned to be accessed via a ramp system and sublevels spaced at 20 m intervals for “conventional long hole” stoping. Accesses will be connected to haulage levels on 925, 775 and 1075 via drifts and ore passes.

The mine extraction sequence for Zone 6 is using a primary-secondary stoping arrangement with cemented rock fill being used in the primary stopes. The strike length is set at 20 m for all stopes (primary and secondary). The delivery of cemented rock fill to the upper portion of the zone will be initiated from the 435 level cement plant. From here a slurry hole has been drilled down to 775 level backfill system, which will deliver cement to the lower portion of the zone. Secondary stopes are planned to be filled with rock fill produced during development of the ramp and footwall drifts.

Upper Zone 6 is currently transitioning to the Avoca mining method for the extraction of its reserves. If proven to be viable, it is expected that this mining method will be incorporated into the lower portions of the zone.

Ore will report to one of three rail haulage levels (775, 925, or 1075 level, depending on the stopes elevation) via an internal ore pass system. Ore will then be trammed on rail to the shaft ore pass system.

Zone 7 is planned to be accessed via a ramp system and sublevels spaced at 20 m intervals for open stoping. Accesses will be connected to the 435 haulage level via drifts and ore passes.

The mine extraction sequence for Zone 7 is using a primary-secondary stoping arrangement similarly to Zone 6. Cemented rock fill being will be used in the primary stopes and secondary stopes will be filled with rock fill produced during development of the ramp and footwall drifts. The strike length is set at 20 m for all stopes (primary and secondary). The delivery of cemented rock fill to the upper portion of the zone will be initiated from the 435 level cement plant.

V-93 is a steeply dipping ore body located to the south of Zone 4 and above 775 level on the west end of the mine. The mineral reserves for V-93 are estimated at 100,184 tonnes grading at 4.59 g/t.

V-93 Zone is planned to be accessed from a ramp system connected to the 775 level with sublevels spaced at 20 m intervals. The zone is planned to be mined using longitudinal long hole retreat method. The stopes will be backfilled using cemented rock fill from the planned 775 level backfill system. Rock fill will be provided from development headings or could be trammed from Zone 6 development when available.

The Holt Mill was constructed in 1988 and was originally designed for a throughput of 1,360 tpd. Expansions in 1988 and 2001 increased the throughput to 2,500 tpd and 3,000 tpd, respectively.

Surface ore storage is a total of 4,900 t in three silos, the Holt headframe bin (900 t) and two other separate storage bins (1,000 t and 3,000 t). Ore can be delivered to the mill from the Holt Mine by conveyor or from a separate surface dump that enters a 100 tonne hopper, and then can be fed to either of the two storage bins.

The grinding circuit consists of a 5 m diameter by 6.1 m long Allis Chalmers ball mill, converted to a SAG mill, a 4 m diameter by 5.5 m long Allis Chalmers ball mill and a 3.6 m diameter by 4.9 m long tertiary ball mill, all operating in series and in closed circuit. The details of the grinding circuit are shown below in Table 16-1. The grinding circuit is controlled by a Wonderware system and Modicom programmable logic.

The primary cyclone cluster consists of six 381 mm (15”) Krebs D15B cyclones. A secondary cyclone cluster consists of twelve 254 mm (10”) Krebs gMAX cyclones with an Outokumpu PSI-200 online analyzer. The secondary cyclone cluster feeds a 27 m (90 ft) Eimco thickener. The thickener underflow feeds a pre-aeration tank, which gravity feeds five carbon-in-leach (CIL) tanks in series. The tank system is conventional gravity flow for slurry with counter-current carbon advancement

Precious metal stripping is performed in batch operations, advancing 2.7 t of loaded carbon through a 1.2 m by 2.4 m (4 ft x 8ft) Simplicity screen. Carbon is transferred to an adsorption column where a Zadra process is utilized as the gold elution method. Barren solution is circulated through two shell and tube heat exchangers and a 360 kW electric inline heater.

The resulting pregnant solution is pumped from the solution tank to an electro-winning cell. The gold precipitate is further refined using a 125 kW Inductotherm furnace and the doré bars are poured in a seven mould cascade arrangement. After stripping, the carbon is regenerated in a rotary kiln, quenched, screened and returned to the process. Carbon fines are collected in a tank, filtered in a Perrin press, and packaged for sale.

Reagents and operating supplies for the mill, such as process chemicals and grinding steel, are stored in the reagent storage building attached to the concentrator at the south end of the building.