The Mexican Hat Property lies within the southeastern portion of the Basin and Range Province, a physiographic domain encompassing much of Nevada, southeast California, southern Arizona and parts of New Mexico.

Gold and silver mineralization is associated with moderate to strong oxidized zones of hematite and limonite. Hematite and limonite are directly related to and fill, in part, dominant NE/SW fault and related fractured zones including secondary NW/SE fault and fractured zones. A dark metallic sulphide has been locally observed and may be a silver sulfa-salt. Hematite may be the result of low- temperature alteration of primary or secondary magnetite. Limonite, a secondary mineral after pyrite is common in surface oxidized zones. Malachite and azurite was observed in several locations across the property within trachyte andesite. In addition, the main elevated metal assemblage from assay results include Au, Ag, As, Hg and Sb. Limits of mineralized zones have not been determined. No sulphides or visible gold has been identified from surface exploration campaigns.

Three main types of alteration are recognized on the Mexican Hat property. First, carbonate alteration is the most common within all Tertiary volcanic rocks mapped on the property. Carbonate alteration is pervasive and ranges from weak to strong. Second, weak propylitic alteration (epidote + weak chlorite in part) was observed and is association with zones of fracturing. Third, weak to moderate silicification was observed within and adjacent to some extensional structures. Sericite and K- Feldspar alteration typical of low sulphidation alkali epithermal deposits may be present but these types of alteration were not observed. A Pima or suitable alteration survey may be useful in identifying all alterations present in the main elevated gold/silver zones.

Porphyry-style mineralization including skarn- type end members containing economically recoverable copper, gold, and sometimes lead, zinc, silver and molybdenum occur in this part of Arizona. The Courtland Gleeson district extends up to and may include the Mexican Hat Property. This mineralization is primarily hosted within Mesozoic sediments and younger intrusions. Placer gold deposits occur in places in washes near the base of the Turquois Mountains.

Younger mineralization hosted in rocks including Tertiary volcanic rocks occur in the area, and at Mexican Hat. The association of alkaline to subalkaline volcanic rocks and the presence of low sulphide concentrations together with the geochemistry of these rocks indicates that the Mexican Hat Property is a low sulphidation epithermal gold deposit.

The Mexican Hat Project is planned as a conventional hard rock surface truck-and-loader mining operation producing 15,000 tpd (5,475 kt/a) of Inferred Mineral Resource feed for the heap leach pad supported with a total mining rate of 58,000 tpd (20,880 kt/a) of material. The mine life is approximately 5-6 years where there will be a year of preproduction and a partial year in year 5.

Pit bench heights will be 6 meters high for mining. Drilling will be completed with a fleet of five rotary blast hole rigs with 23,500 kg pull down force. Blast holes will be drilled with 6 3/4 in. (17.15 cm) diameter holes. The blasted rock will be loaded into 100 t (89.4 tn) haul trucks using three 11.5 cu m front end loaders.

The model received by IMC was a nonstandard block size, sub-block block model that was developed by Tetra Tech. In preparing the block model for mine planning usage, IMC applied mining modifying factors in which the sub- blocks were diluted to 6x6x6 m whole blocks. Where the summation coverage of the model estimated nonstandard sub-blocks did not constitute a whole block, the remainder of the whole block was diluted with zero grade waste material. The sub-block model also did not reference a practical bench level designation applicable to a surface open-pit operation and so it was re-blocked to a whole block model that translated the block bench levels down in elevation by 0.06 m. This resulted in bench levels that were whole numbers – for example, the 1414 level as opposed to the original 1414.06 level.

Mine Planning Parameters:
Haul Road Width - 25 meters.
Haul Road Grade - 10% Maximum.
Interramp Slope Angles - 45 degrees.
Operating width between pushbacks - 100 meters nominal.

Over the life of the mine, feed will be delivered to the stockpile adjacent to the crushing plant. The material will be fed to the crushing plant using a front-end loader, and will be crushed and transported to the heap leach pad via an overland conveyor. The feed will be stacked onto the heap using a radial stacker and then leached with a weak cyanide solution to extract the precious metal values. The gold will then be recovered from the pregnant solution in the carbon plant by adsorbing the dissolved gold onto activated carbon followed by desorption, electrowinning, retorting and smelting to recover the gold as a final doré product.

Run-of-mine (ROM) material will be trucked from the mine to a stockpile close to the primary crusher and subsequently reclaimed with a front-end loader (FEL). The FEL will dump feed into a surge bin. A vibrating grizzly feeder will draw feed from the surge bin, with the feeder oversize reporting to a jaw crusher. The grizzly feeder undersize material will bypass the primary crusher and will combine with the crusher product on the primary discharge belt conveyor.

The heap leach pad will be designed to be constructed in phases to Arizona Department of Environmental Quality (ADEQ) and Best Available Demonstrated Control Technology (BADCT) standards. The leach pad extends from an elevation of 1,398 meters at the toe of the process ponds to an elevation of 1,412 meters at the western edge of the leach pad. The grade of the lined base receiving feed will range from 1 to 2%. In total, the leach pad will have a total lined area of 46.1 hectares. The final reclaimed surface of the leach pad will be graded to 3H:1V (horizontal to vertical) side slopes and will be covered with 0.6 m of growth media. The leach pad design provides a total capacity of approximately 25.1 Mt using an average dry density of 1.5 tonnes/m3 for stacked feed.

A carbon ADR circuit will be used at the Mexican Hat Mine to recover gold and silver from the pregnant solution. The ADR plant will recover and send concentrated gold solution to the refinery where the final marketable doré bars are produced. Pregnant solution from the heap leach pad will flow by gravity to the pregnant solution tanks. From the pregnant solution tanks, the solution will be pumped to the ADR plant, where soluble gold and silver will adsorb onto activated carbon. Adsorption of the gold onto activated granular coconut shell carbon will be conducted in a five-stage counter current carbon-in-column (CIC) circuit. Carbon is advanced from column to column counter current to the pregnant solution flow so that the highest-grade carbon contacts the highest grade pregnant solution and the most active fresh carbon contacts the lowest grade solution.

Loaded carbon from the first adsorption column will be pumped to an acid wash vessel and will be acid washed by circulating dilute hydrochloric acid upwards through the bed of carbon to remove scale build-up (mainly calcium) to maintain the carbon’s ability to recover gold and expose the surface to improve gold elution efficiency. Residual acid in the acid wash vessel will be neutralized with caustic before the loaded carbon is transferred to the strip (elution) vessel. Hot caustic cyanide solution will be pumped through the strip vessel to remove the gold and silver from the loaded carbon. Elution is conducted at 100 psi and 150°C for up to ten hours. Sodium hydroxide will be added to the stripping solution to aid stripping and provide electrolyte for the subsequent electrowinning stage.

Recovery of precious metals from the rich pregnant strip solution will be conducted in a single electrowinning (EW) cell. Electrowinning removes the precious metals from the pregnant solution by passing direct current through an electrowinning cell. The rich strip solution is transferred to the electrowinning cells. The precious metal ions transfer from the solution to the stainless-steel wool cathode and deposit onto the steel wool as a weakly bonded sludge. The barren EW solution is then returned to the stripping circuit, completing the elution cycle. The barren strip solution from the electrowinning cell will be collected in the EW barren return tank and pumped to the strip solution tank for reuse in the strip circuit. The sludge in the electrowinning cell will be washed off the cathodes in batches and recovered as a damp cake in the cathode sludge filter press.

The filtered cake will be retorted to remove and recover mercury prior to smelting the dried sludge to produce Doré bars. Filtered cake will be collected in pans. The pans will be placed in a mercury retort system for several hours. The retort will heat the filtered cake to approximately 650°C to vaporize mercury. The retort temperature will be ramped up gradually to enable the sludge to dry completely before mercury is vaporized and to allow time for the mercury to diffuse to the solid surfaces. Retort vapor will be withdrawn from the retort by a vacuum pump, which will pull the vapor through a condenser where the mercury will condense and flow into a mercury collection compartment. Mercury will be removed as required.

Following a cooldown period, the dried (retorted) cake will be mixed with fluxes and charged to an electric induction furnace and heated to approximately 1,230°C. When the furnace charge is fully molten, it separates into two distinct layers: the slag (on the top) and metal (on the bottom). The slag layer, containing fused fluxes and impurities, will be poured first into conical pots. Once slag has been removed, the melted gold and silver (metal layer) will be poured into molds to form Doré bars.

Bars will be cooled, cleaned, weighed, and stamped with an identification number and weight. Doré bars will be the final product of the plant which will be shipped to the market at 90-95% Au/Ag purity.