The Sleeping Giant deposit is a member of the type of gold deposits formed by groups of veins with gold associated with sulphide minerals and whose geometry the stress field in the rocks at the time of vein formation (Birkett, 2008).

At the Sleeping Giant mine, gold mineralization is found in quartz-sulphide veins. The best mineralized veins typically contain four sulphide minerals: pyrite, pyrrhotite, chalcopyrite and sphalerite, which form 5 to 60% of the veins. The typical vein thickness is between 20 and 80 cm with average grade between 35 and 85 Au g/t (uncut channel sample analyses). In addition to gold, the veins contain silver and a small proportion of copper and zinc. The gold:silver ratio is about 1:2. Zones 20 and 30 have a lateral/vertical continuity of 300 m/670 m; that is to say, they have a much greater vertical continuity than lateral. In Zone 8, the lateral/vertical continuities are more than 600m/500 m.

Gold mineralization occurs in four cogenetic styles that are rich in base-metal sulphides: (1) narrow quartz veins, which are economically most important, (2) stratabound ore within sedimentary horizons, (3) quartz veining within QFP dikes, and (4) quartz veinlet arrays. Ore controls correspond to primary permeable features such as: (1) stratigraphic contacts, (2) specific lithological units, (3) synvolcanic faults and (4) preexisting joints. The geometry of the orebody displays an increasing complexity toward the south, i.e., toward the paleosurface (Gaboury, 1999).

Important veins seem associated with swarms of porphyry dykes. For example, zones 20, 30 and 8 are transversal structures to a series of sericitized quartz porphyry dykes. Gold vein emplacement occurred before the regional deformation and the stratigraphic orientation change in the west sector affects the ore zones’ orientations. Veins bend in connection with stratigraphy. ENE–ESE veins usually have a steep dip to the south even though NW–NE veins have a moderate dip to the east.

Ore veins occur mainly to the north, south and west of the main dacitic mass. The image is then an ore crescent on the west perimeter of the Sleeping Giant intrusive system. Veins in this crescent show a certain periodicity. Therefore, moving away from the intrusive centre, a recurring spacing between ore structures is shown. With regard to spatial distribution of this vein-type system, several veins occur at the level of the fold hinge line. Since veins were in place before the folding, it is considered this abundance shows that this hinge line is a site of favourable preservation, in contrast to the limb where veins might have been boudinaged. The hinge line then appears as a significant target where well-preserved ore veins can be found.

Vein mineralization, which is the only economic ore, is composed of 5 to 80% (mean of 25%) of sulphides (pyrite, pyrrhotite chalcopyrite, sphalerite and arsenopyrite). Quartz is the dominant gangue mineral, with lesser amounts of chlorite, sericite, tourmaline and metamorphic calcite and actinolite. Selvage alteration is weakly developed (chlorite-sericite) to absent (Gaboury, 1999).

Three methods are in current or recent use to extract ore. The long-hole method was discontinued during 2002 because of the shallow dip in zone 8 as well as the high dilution which was obtained. Since then, the use of this method is limited to the pillar recovery and to complete stopes in which mining with other methods is not appropriate. The type of mining method is determined according to the studied zone’s dip:

Slope over 65º: Long-hole and shrinkage stope extraction. When used, the longhole method consisted in excavating a raise to a maximum length of 65 meters between two sub-levels. Following this step, three levels are excavated, with maximum length 70 meters and they are vertically spaced between 15 to 17 meters, according to a “dice five” pattern. When drilling is completed, blasting of the three benches can be carried out. The shrinkage method is described below.

Slope between 65º and 45º: Shrinkage stope mining with some stopes by longhole methods.. Shrinkage stope mining consists in excavating a raise to a maximum length of 85 meters between two levels. The length of the stope is usually between 20 and 100 meters, that is to say blocs of 7 000 to 35 000 tonnes. The ore is broken in horizontal slices of approximately 2.6 m thickness, working from the base to the top of the stope. For each slice, 30% of the blasted ore is removed therefore allowing employees to move along the stope on the broken ore. When the ore breaking is completed, the remaining ore can be extracted from the stope. With this method, the recovery rate is between 95% and 100%.

Slope below 45º: Room and pillar extraction. During room and pillar extraction, the ore is blasted in slices, but contrary to shrinkage stope mining methods the broken ore is removed immediately in order to allow workers to circulate in the stope. Therefore, no access raise is required. The size of the rooms and pillars is determined according to the rock mass stability. Usually, rooms are 6,5 meters by 6,5 meters and are separated by pillars which can be recovered in part once the stope is completed. The mining recovery is typically at least 85 % when using this method.

Among the assets that Abcourt will acquire, there is a mill with a capacity of 700 to 750 tonnes of ore per day, that is about 250,000 tonnes per year. This capacity is adequate to treat the Elder and the Sleeping Giant production. The process is carbon in pulp.

Ore is fed through a grizzly into a crushing plant with a primary jaw crusher and two cone crushers with screening, then to a rod mill and two ball mills to produce a pulp that undergoes conventional leaching followed by a CIP (carbon in pulp) circuit, stripping facilities, electrowinning and an induction furnace to produce gold dore.