The Cerro del Gallo copper-gold-silver deposit can be considered to be a member of a distinct subclass of “reduced” porphyry-style copper-gold mineralization as first proposed by Rowins (2000c). These reduced porphyry copper-gold deposits lack primary hematite, magnetite and sulphate minerals, but contain abundant hypogene pyrrhotite, commonly have carbonic ore fluids, and are associated with ilmenite-bearing, reduced I-type granitoids (Rowins 2000c). Cerro del Gallo displays all these features. In addition, there is a consistent pattern of higher temperature potassic alteration overprinted by lower temperature propylitic-style mineral alteration. Propylitic alteration boundaries are gradational and irregular, and more widespread than potassic alteration. This alteration pattern is consistent with many other porphyry copper-gold deposits throughout the world. Tellurium-bearing minerals are also common in porphyry copper-gold deposits, as they are at Cerro del Gallo.

San Anton Project has several epithermal veining systems, one of which, the Ave de Gracias, transects Cerro del Gallo. None of the vein systems have had chemical determination for classification of sulphidation type, although there are several geological characteristics similar to low sulphidation epithermal deposits, all them determined by geological mapping and geological description. Some of these characteristics are:
a) sericite or illite ± adularia, clorite alteration minerals;
b) filling cavities/porosities vein type, banding and hydrotermal breccias;
c) carbonate replacement textures;
d) low content of bulk sulphur, low presence base metals (Pb, Zn).

The strongest gold mineralization is associated with quartz stockwork veining within the wallrock annulus around the felsic stock, and diminishes outward accompanied by reduced fracture density and quartz veining. Sulphides make up less than 2% by volume of the mineralized rocks. Gold-copper mineralization is zoned concentrically around the felsic intrusive with higher grade gold mineralization within a wallrock annulus proximal to the felsic intrusion, and higher grade copper mineralization outwards of the gold zone. In general there is an antipathetic relationship between gold and copper grade. Zinc mineralization is anomalous outside the copper zone. Metal zonation boundaries are gradational and there is an overlap in the gold-copper zone and the copper-zinc zone, although normally the mineralized zinc zone is stratabound in marine sediments and siliciclastic deposits. Molybdenite is rarely observed, but where present is found in the felsic intrusive and silicified contact with the wallrock tuffs.

Pyrite [FeS2] is the dominant iron sulphide mineral with accessory pyrrhotite [Fe1-xS] and marcasite [FeS2] dispersed throughout the mineralized system. Pyrite occurs in two forms; as euhedral to subhedral cubic crystals and crystal aggregates in veins and disseminations of primary origin, and also as fine-grained porous ragged patches of retrogressive origin after pyrrhotite (Mason 2005a). Pyrrhotite is most common in the outer copper zone. It is magnetic and in sufficient concentration to form a high amplitude magnetic anomaly around the felsic intrusive. This magnetic anomaly is donut-shaped. Pyrrhotite is often selectively replaced by clean pyrite, pseudo-colloform melnikovite pyrite, and marcasite. It is likely that pyrrhotite and pyrite formed together at an early stage during the main potassic alteration event, but was quickly over grown by pyrite. Most sulphide minerals are fine grained with grains generally being <0.5mm in diameter with the exception of arsenopyrite which is slightly coarser grained. Pyrite is free of arsenic.

Native gold occurs as free grains within vein quartz and inclusions within pyrite, chalcopyrite and bismuthinite. Gold grains range in size from generally 0.5-4 microns in diameter to rarely 10-20 microns (Mason 2005a; Mason 2006a; Townend 2006). Electron-probe microanalysis on a limited number of native gold grains indicates gold has a fineness of 860-880 with silver as the other mineral accompanying gold (Mason 2006b, Mason 2007). In terms of geochemistry and all elements assayed, gold has the strongest correlation with bismuth.

Silver-bearing minerals are abundant, however the dominant silver-bearing mineral is not known at this time. Galena and cosalite [Pb2Bi2S5] are both argentiferous, containing 2-3% silver sequestered in the lattice (Mason 2005a). Silver also occurs as small grains of native silver and pavonite [(Ag,Cu)(Bi,Pb)3S5] (Rowins 2000b), possible ruby silver (Torres 1997), as either pyrargyrite [Ag3SbS3] or proustite [Ag3AsS3], 1-2 microns in diameter, and tetrahedrite [Cu12Sb4S13]. Native silver grains contain significant amounts of antimony, up to 8% weight percent (Mason 2005b). Pavonite is commonly associated with the main felsic intrusive, while tetrahedrite is common in the wallrocks (Rowins 2000b). Townend (2006) identified fahlore, a general name for the tennantite-tetrahedrite series of copper sulphosalts, rather than tetrahedrite. As may be expected, there is a very strong correlation between silver and lead in the geochemical data.

Chalcopyrite [CuFeS2] is the most common base metal sulphide phase and occurs in fracture veinlets associated with intense silicification and as disseminations. Chalcopyrite occurs in both granular quartz veins accompanying potassic alteration, and euhedral quartz veins accompanying propylitic alteration. Chalcopyrite is commonly closely associated with pyrite and marcasite, and rarely as inclusions in coarse arsenopyrite (Townend 2006). Traces of bornite [Cu5FeS4] have also been reported (Mason 2006b; Townend 2006), however this mineral is not volumetrically significant. Minor secondary copper minerals including malachite [Cu2(CO3)(OH)2] and azurite [Cu3(CO3)2(OH)2] have formed through weathering processes and are present in surface rocks and near surface rocks. Native copper, covellite [CuS] and chalcocite [Cu2S] are found deeper in the regolith profile, and their formation is attributed to supergene weathering processes.

The Cerro del Gallo project has been planned as an open-pit truck and shovel operation. The truck and shovel method provides reasonable cost benefits and selectivity for this type of deposit. Only open-pit mining methods are considered for mining at Cerro del Gallo.

The processing plant has been designed to have excess capacity to anticipate higher metal recovery in the future. The design throughput rate has been determined by Cerro Resources and will be 4.5 Mt/a.

The flow sheet design is broadly based upon a conventional cyanide heap leach and gold on carbon recovery technologies but will incorporate a SART processing stage to facilitate copper removal prior to gold recovery. The plant design is based on the treatment of both fully and partially oxidised ores, with the design grade for oxidised and partially oxidised ore being between 0.60 - 0.75 g/t Au, 13.7 - 16.2 g/t Ag and 562 - 867 ppm Cu, as per the mine plan. The plant is planned to produce annually on average:
- 62,246 oz of Au and 17,185 oz of Ag in doré;
- 884 t of Cu, 2096 oz of Au and 1,052,604 oz. Ag as a sulphide precipitate.

The proposed processing facility comprises the following unit operations:
- Crushing in three stages to -8mm, using a HPGR as a tertiary crusher;
- Agglomeration and stacking;
- Cyanide heap leaching;
- SART to recover a high grade copper/silver precipitate for further processing or sale;
- Gold recovery via carbon in columns adsorption; - Elution;
- Electrowinning and gold room refining;
- Carbon regeneration;
- Reagent mixing, storage and distribution;
- Water supply, recovery and distribution services;
- Air supply and distribution services.