Phoenix is a skarn-hosted polymetallic massive sulfide replacement deposit.

Au-Cu-Ag-Pb-Zn skarn mineralization at Phoenix is centered about the Eocene Copper Canyon granodiorite porphyry stock. Paleozoic sedimentary rocks within two miles of the stock have undergone strong thermal metamorphism (hornfels) and metasomatism (skarn). Metal zonation is manifest by a CuMo core close to the stock grading outward into proximal Cu-Au-Ag, Au-Ag and distal Pb-Zn-Ag mineralization.

The Lone Tree gold deposit, Nevada is hosted in Paleozoic calcareous sedimentary rocks. Mineralization is dominantly controlled by high-angle normal faults and fracture sets, as is alteration. Mineralization occurs in the form of disseminations, micro and macro veins, and as a matrix to angular breccia clasts. The paragenesis of minerals indicate four stages of mineralization. The first stage is identified by brecciated quartz and minor pyrite. The second stage is the main gold stage of mineralization comprising quartz veins, kaolinite, pyrite, marcasite, arsenopyrite, gold, sphalerite, and chalcopyrite.This is overprinted by a third stage economic gold mineralization along with barite and pyrite. Free gold grains in stage 2 occur in a quartz and clay mineral assemblage in association with pyrite. The last stage is supergene mineralization producing covellite, chalcocite, native copper, hematite, and goethite.

Main alteration types are decarbonatization, silicification by multiple generations of silica, and argillization due to the development of kaolinite, illite/smectite, and alunite.

Gold mineralization at the Lone Tree deposit is primarily confined to fault zones and fracture sets, where sedimentary host rocks experienced decarbonatization, silicification (by repeated introduction of hydrothermal silica), and argillization (by development of clay minerals especially hypogene kaolinite).

Four stages of mineralization have been identified at the Lone Tree deposit. The first stage of mineralization is represented by brecciated quartz and minor pyrite. The second stage, main gold sulfide mineralization containing quartz veins, kaolinite, pyrite, marcasite, arsenopyrite, gold, sphalerite, and chalcopyrite is overprinted by a third stage of mineralization comprising barite, pyrite, and gold. Free gold grains occur in quartz and clay mineral assemblage in association with pyrite in stage 2 mineralization. The fourth stage is supergene mineralization and includes covellite, chalcocite, native copper, hematite, and goethite.

Fluid inclusion and gas composition data indicate multiple sources for the main gold stage mineralizing fluids as magmatic, crustal, and evolved meteoric waters. Fluid inclusion data indicates fluids had temperatures of 185 to 411 °C and salinity of 1.23 to 41.4 eq. wt. % NaCl. High salinity fluids (28.6-41.4 eq. wt. % NaCl) along with high N2/Ar ratios and high C02 concentrations demonstrate a magmatic input.

The Phoenix surface mine’s available mining fleet consists of three shovels and twenty 240 ton haul trucks.

Lone Tree’s available mining fleet consists of two haul trucks, which range from 150 tons to 190 tons, to rehandle leach material for residual leaching operations.

Process facilities include a flotation mill, which processed approximately 12.2 million tons of ore in 2018, a carbon-in-leach plant, a copper leach pad and a solvent extraction electrowinning (“SX/EW”) plant. The copper leach and SX/EW plant allows for the production of copper cathode.

At Phoenix, ore containing copper and gold is crushed to a coarse size at the mine and then transported via conveyor to a process plant, where it is further crushed and then finely ground as a slurry. The ore is initially treated by successive stages of flotation resulting in a copper/gold concentrate containing approximately 15% to 20% copper. Flotation concentrates are also processed via a gravity circuit to recover fine liberated gold and then dewatered and stored for loading onto ships or rail for transport to smelters. The flotation tailings have a residual gold content that is recovered in a carbon-in-leach circuit.

In addition, at Phoenix, copper heap leaching is performed on copper oxide ore and enriched copper sulfide ore to produce copper cathodes. Heap leaching is accomplished by stacking uncrushed ore onto impermeable, synthetically lined pads where it is contacted with a dilute sulfuric acid solution thus leaching the acid soluble minerals into a copper sulfate solution. The copper sulfate solution is then collected and pumped to the solvent extraction (“SX”) plant. The SX process consists of two steps. During the first step, the copper is extracted into an organic solvent solution. The loaded organic solution is then pumped to the second step where copper is stripped with a strong acid solution before being sent through the electrowinning (“EW”) process. Cathodes produced in electrowinning are 99.99% copper.