According to Hein (2003), the Batman and Quigleys gold deposits of the Mt. Todd Mine are formed by hydrothermal activity, concomitant with retrograde contact metamorphism and associated deformation, during cooling and crystallization of the Tennysons Leucogranite and early in D2 (Hein, submitted for publication). It is speculated that pluton cooling resulted in the development of effective tensile stresses that dilated and/or reactivated structures generated during pluton emplacement and/ or during D1 (Furlong et al., 1991), or which fractured the country rock carapace as is typical during cooling of shallowly emplaced plutons (Knapp and Norton, 1981). In particular, this model invokes sinistral reactivation of a northeasterly trending channelization basement strike–slip fault, causing brittle failure in the upper crust and/or dilation of existing north–northeasterly trending faults, fractures, and joints in competent rock units such as metagreywackes and siltstones. The generation of dilatant structures above the basement structure (i.e., along a northeasterly trending corridor overlying the basement fault), coupled with a sudden reduction in pressure, and concomitant to brecciation by hydraulic implosion (Sibson, 1987; Je´brak, 1997) may have facilitated channelization of predominantly metamorphic fluid in the intermediate contact metamorphic aureole (possibly suprahydrostatic-pressured) and into the upper crust (Furlong et al., 1991; Cox et al., 2001). Rising fluids decompressed concurrent with mineral precipitation. Throttling of the conduit or fluid pathways probably resulted in over pressuring of the fluid (Sibson, 2001), this giving way to further fracturing, etc. Mineral precipitation accompanied a decrease in temperature although, ultimately, the hydrothermal system cooled as isotherms collapsed about the cooling pluton (Knapp and Norton, 1981).

A variety of mineralization styles occur within the Mt. Todd area. Of greatest known economic significance are auriferous quartz-sulfide vein systems. These vein systems include the Batman, Jones, Golf, Quigleys and Horseshoe prospects, which occur within a north-northeast trending corridor, and are hosted by the Burrell Creek Formation. Tin occurs in a north-northwest trending corridor. The tin mineralization comprises cassiterite, quartz, tourmaline, kaolin, and hematite bearing assemblages, which occur as bedding to parallel breccia zones and pipes. Polymetallic Au, W, Mo, and Cu mineralization occurs in quartz-greisen veins within the Yinberrie Leucogranite; a late stage highly fractionated phase of the Cullen Batholith. The Batman Deposit extends approximately 2200 m along strike, 400 m across dip and drill tested to a depth of 800 m. Drilling indicates the Batman mineralization to be open along-strike and down-dip.

The mineralization within the Batman deposit is directly related to the intensity of the north-south trending quartz sulfide veining. The lithological units impact on the orientation and intensity of mineralization. Sulfide minerals associated with the gold mineralization are pyrite, pyrrhotite and lesser amounts of chalcophyrite, bismuthinite and arsenopyrite. Galena and sphalerite are also present, but appear to be postgold mineralization, and are related to calcite veining in the bedding plains and the east-west trending faults and joints. Two main styles of mineralization have been identified in the Batman deposit. These are the north-south trending vein mineralization and bedding parallel mineralization.

The Quigleys deposit mineralization was interpreted by Pegasus and confirmed by Snowden to have a distinctive high-grade shallow dipping 30°-35° northwest shear zone extending for nearly 1 km in strike and 230 m vertical depth within a zone of more erratic lower grade mineralization. The area has been investigated by reverse circulation drilling method (RC) and diamond drilling by Pegasus and previous explorers on 50 m lines with some infill to 25 m.

Drillhole intersections generally revealed an abrupt change from less than 0.4 g Au/t to high grade (>1 g Au /t) mineralization at the hanging wall position of the logged shear, but also revealed a gradational change to lower grade mineralization with depth. Some adjacent drillholes were also noted with significant variation in the interpreted position of the shear zone, and some of the discrepancies appeared to have been resolved on the basis of selection of the highest gold grade. While the above method may result in a valid starting point for geological interpretation, the selection of such a narrow high grade zone is overly restrictive for interpretation of mineralization continuity and will require additional work prior to estimating any resources.

he Project is designed to be a conventional, owner-operated, large open-pit mining operation that will use large- scale mining equipment in a blast/load/haul operation.

Impact crushing work index (CWi) tests were performed on eighty individual samples from the 2011 drill cores. The CWi values ranged from 3.2 kWh/t to 26.5 kWh/t. For design purposes, a CWi of 20 kWh/t was selected, 75% of the maximum.

The run of mine ore from the pit would have a maximum particle size of 1000 mm and P80 to the primary crusher of 450 mm. Two stages of crushing, primary and secondary, would be required to reduce particle size to a P80 of 31.5 mm as feed to the HPGR tertiary crushers. A single gyratory crusher would be sized for primary crushing duty in reducing ore size to a nominal P80 of 120 mm. Two secondary cone crushers operating in parallel and in closed circuit with two sizing screens cutting at 40 mm, will be used to produce the feed to the HPGRs at product size P80 of 31.5 mm.

The primary crusher power was calculated using both the FLSmidth (FLS) gyratory calculation model and the Metso Bruno model. Using the CWi of 20 kWh/t and a fall through percentage of zero to simulate peak conditions, both models provided a peak primary crushing power requirements of approximately 574 kW and 576 kW respectively to reduce a feed F80 of 450 mm to a product P80 of 120 mm.

Secondary crushing with closed circuit screening was modeled by Metso Corporation (Metso). Two MP1250 cone crushers operating in parallel will be used to reduce the primary crusher product to a final product P80 of 31.5 mm, for 50,000 tpd. The peak power demand per crusher will be 606 kW.

HPGR power requirements to reduce the HPGR feed to a final product P80 of 3.25 mm was shown by the Polysius AG (Polysius) testwork to be 1.9 kWh/t of feed to the HPGR. The feed to the HPGR is the sum of new feed plus the recirculating load screen oversize material. The total feed to the HPGR is 2.45 times the fresh feed rate. HPGR testwork supported vendor recommendations call for two HPGR Polycom 24/17-8, each equipped with 2 x 3,300-kW drives.

Thickener design was performed by Outotec based on the testwork results. A 45 m diameter thickener is required. Flocculant consumption of 15 g/t can be expected. Maximum compaction of 63% solids was achieved at a bed depth of 240 mm, there would be no difficulty achieving the target of 55% solids in underflow and clear overflow.

The optimum leach and adsorption density as determined by the SPX testwork was 55% solids. The leach and adsorption circuits were modeled. A six stage adsorption is required to minimize solution losses. Dissolved gold in residue solution will be =0.010 ppm. At the planned gold head grade, the system will produce a loaded carbon head grade of approximately 1,250 g/t, and carbon movement requirements will be in the order of 30 tpd.