The Zonia deposit is hosted by steeply dipping, northeast-trending, Precambrian metamorphic rocks of the Yavapai Series, comprising schistose subvolcanic intrusions, volcanic flows and tuffs, and finegrained sedimentary rocks, enclosed in Precambrian granitic plutons. Portions of the area are covered by post-mineralization Quaternary basalt, fanglomerate, and alluvial material. Mineralized units consist mainly of highly variably foliated quartz- monzonite, felsic schist, and diorite, with highly schistose phyllite and chlorite schist along the southeast margin.

The Zonia copper deposit has a north-easterly strike length of about 2,400 m (8,000 ft) and horizontal width varies from 60 m (200 ft) to 460m (1,500 ft). The deposit consists of multiple mineralized zones that dip at various angles to the northwest. The zones are generally in the order of 200 ft (60 m) wide and commonly occur in sub-parallel groups of three or more. Most of the deposit has been drilled to depths of 120 m (400 ft) or less.

The Zonia copper oxide deposit is the highly oxidized portion of a previously supergene-enriched metamorphosed porphyry deposit. Oxidation of the original chalcopyrite mineralization and younger secondary supergene chalcocite has been pervasive and deep, extending down over 250 metres (874 feet) in the central pit at the historical Cuprite mine shaft. Chrysocolla, malachite, azurite, tenorite, and cuprite are the most common copper minerals.

The Zonia project would be mined using conventional open pit methods using off-highway trucks and loaders or shovels. Drilling, blasting, load, and haul would be used to remove overburden waste and leachable material. Waste would be hauled to disposal sites located as near as possible outside of the largest hypothetical pit rim. Ground pressure from stacking the waste is not expected to impact pit wall stability.

Leachable material would be hauled from the pit to the crusher. Crushed material would be transported via conveyors to the leach pad.

For the base case, contractor mining operations were selected.

Pit Shell Selection for Design
Each pit was evaluated at cutoff grades varying in 0.01% increments from 0.12% to 0.22% and using preliminary surface mining costs, processing costs, and G&A costs to calculate preliminary Net Present Value (NPV) at varying discount rates and Internal Rate of Return (IRR). This preliminary analysis was conducted to identify the pits with the greatest potential for economic success. The preliminary analysis indicated that the $2.00/lb pit had the greatest potential for economic success.

The pit shell for the $2.00/lb pit was imported into Geovia GEMS™ to design the ultimate pit layout using 45 degrees batter angle, 20-foot bench height, 12.7-foot bench width, 10% ramp grade, and ramp width of 100 feet for all but the lowest four benches, which were given a single-wide 50-foot ramp width.
< ........

- subscription is required.

- subscription is required.

- subscription is required.