The polymetallic gold-silver mineralization at Cerro Moro is of the low- to intermediate-sulphidation epithermal vein type. Individual prospects vary from simple, single veins to complex vein systems with spur and cymoid loop structures. Limited quartz stockwork veinlets are also present peripheral to the main veins.

High-grade gold and silver mineralization is strongly associated with the presence of sulphides such as: pyrite, sphalerite, galena, acanthite and chalcopyrite. Detrimental toxic elements such as arsenic and mercury are at relatively low levels. The presence of yellow sphalerite and adularia are indicative of low temperature mineralization formation. At least two mineralization pulses have been observed. The first pulse deposited clean white quartz veins with low sulphide content and is generally poorly mineralized. This has been interpreted as the product of shallow, circulating meteoric dominated water with scarce mixing of magmatic water. A second, later pulse, consisting of black silica is rich in sulphides and hosts high-grade mineralization. Precious metal deposition is interpreted to be the product of mixing of magmatic dominated water with meteoric waters. Boiling textures, vein breccias and repeated quartz overgrowths with sulphidic ginguro bands are also observed.

The mineralization is hosted in sub-volcanic and volcanic rocks, which are interpreted to belong to the Jurassic age Chon Aike and La Matilde Formations. In general, the Project area is composed of many structural blocks produced by a conjugate set of north-west and north-east faults. Both fault directions contain mineralized quartz veins. In the eastern and central part of the Project, north easterly trending faults control the mineralization at the Deborah, Belen, Maria, Michelle, Barbara and Ana prospects. In the central and western part of the Project, north westerly trending structures are the dominant control to the mineralization at the Escondida, Carla, Esperanza, Nini, Gabriela, Carolene, Lucia, Dora, Moro, Florencia, Natalia, Tres Lomas and Lala prospects. The Escondida Structure has a much larger segment of east west strike in the area of the recently discovered Zoe Shoot. Several secondary eastwest structures occur between the primary north-west structures, and these control the mineralization at the Patricia, Loma Escondida and Carlita prospects. The width of the veins varies generally from 1 to 5 m, but veins may locally attain widths of up to 10 m. The strike length of individual veins is variable, generally between 200 m and 1 kilometre. The Escondida structure has been defined by drilling for more than 8 km, and remains open along strike and also at depth.

Improved geological, structural and mineralization models developed over the past two years have led to the discovery of numerous high-grade gold-silver polymetallic veins at Cerro Moro. These base metal anomalous Au-Ag veins tend to be recessive and are represented on the surface by either very poorly outcropping quartz vein material or none at all. Extensive cover of Tertiary marine sediments and Quaternary gravels also hinder the location or extensions of some of the veins and targets. Detailed ground magnetic survey data, coupled with IP and resistivity data, has highlighted potential targets that are initially tested via trenching and/or scout drilling, as in the case of the Escondida prospect.

Mining of the narrow, near-vertical gold-silver veins at Cerro Moro is expected to be undertaken using a combination of open pit and underground mining methods.

Cerro Moro open pits will be mined using conventional drill, blast, load and haul techniques. Equipment to be used includes; hydraulic top hammer drill rigs, hydraulic backhoe excavators and 50t mining trucks. Track and wheel dozers, front end loaders and graders will be used to support the operation.

On each bench waste rock will be mined first using backhoes and frontal end loaders to expose the full length of the mineralized veins. The mineral inventory will be mined in a single operation using smaller backhoe equipment to minimize the dilution and mineralization loss.

Maximum pit depth is approximately 110m with the depth of individual pits being determined by the formula described in detail in the study.

A modified bench and fill method will be employed to mine the Cerro Moro high-grade mineralized veins underground. Level spacing used is 16m resulting in a bench height of 12m. This ensures a high degree of accuracy in drilling and blasting of the narrow high grade vein structures, resulting in low dilution and mineral losses.

The levels are accessed through inclined crosscuts connecting the mining horizon to a series of decline haulages, spaced at regular intervals along the mineralized structure. Waste developments are placed in the footwall of the almost vertical mineralized vein structures.

A treatment plant capable of processing 474,500 t/y of the gold-silver mineralized rock from the various deposits at the Project is proposed. The design incorporates both flotation and gravity recovery stages to maximise recovery from the variable mineralogy particularly of the silver minerals. Due to the high silver to gold ratios for the deposits – overall average ratio of 60:1 silver gold – the Merrill Crowe (zinc cementation) process has been included instead of adsorption onto carbon for the recovery of precious metals from the leach solution.

A three stage closed circuit design has been selected for the crushing circuit. The circuit is designed for single shift crushing with a design throughput rate of 200 tonnes per hour.

The proposed grinding circuit design consists of a single stage overflow ball mill that will operate in closed circuit with hydrocyclones, flash flotation and gravity concentration machines. The fine crushed product size and use of a ball mill will enable stable throughput rates to be achieved on each mineralized rock type.

To maximise the gravity recoverable precious metals a flash flotation machine and a centrifugal gravity separator will treat 80% of the cyclone underflow. The water added in the gravity circuit will displace ball mill feed water to minimize the impact on the density in the grinding mill.

The cyclone overflow reports to a conventional flotation circuit to enhance recovery of gold and silver minerals for the subsequent concentrate regrind and leaching stages. The flotation circuit will consist of a single roughing stage of three 10 m³ tank flotation cells.

The combined flash flotation, gravity and rougher flotation concentrates totalling approximately 4.1 t/h of solids will be thickened in the concentrate regrind feed thickener and then reground in an M500 IsaMill™ to a product size P80 of 30 µm and powered by a 200 kW motor.

The intensive leaching circuit consists of five agitated leach tanks. Each tank has a capacity of 50 m³ slurry, resulting is a total leach retention time of 24 hours. Leaching will be conducted at 32% solids using a solution of 1% sodium cyanide and 0.2% sodium hydroxide.

The main leaching circuit design includes a leach feed thickening stage to maximise the recovery of non-cyanide contaminated process water prior to leaching and to minimize the volumetric capacity of the leaching train.

The leach tail will flow to the first of five CCD thickeners which will be used to separate and recover the solution phase carrying the dissolved precious metals from the residue solids. Pregnant solution will be removed from the first CCD thickener. Barren solution from the Merrill Crowe zinc cementation circuit will be added to the fifth (last) CCD thickener as the wash solution.

The Merrill Crowe circuit will be a vendor supplied package with a volumetric capacity of 190 to 380 m³/h.