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).

A mining plan has been prepared to extract 325,000 tonnes of reserves over a 4-year period including one year of pre-production (25,000 tonnes) followed by the three years with an annual production of 100,000 tonnes per year. The remaining 14,221 tonnes of reserves, not extracted by this mining plan, will be extracted later in subsequent operations following additional exploration and development work. There are good possibilities of extending the production period by doing additional exploration work on the indicated resources excluded from the mining plan and on the inferred resources and converting the latter into measured or indicated resources and eventually into reserves.

The mineralization is typically in narrow veins. The dip varies between 30o and 80o. The mining methods will be shrinkage and room and pillars. The long-hole method is not favored but will be used where the other methods are not adequate.

The process used in the mill to treat the gold ore is carbon in pulp. The mill capacity is 700 to 750 tonnes per day. This capacity is sufficient to treat the Elder and the Sleeping Giant ores.

Historically, the gold recovery in this mill has been 97,5%.