The Gunnison Project (North Star) lies on the eastern edge of the Little Dragoon Mountains.

The North Star copper deposit is a classic copper skarn (Einaudi et al, 1980 and Meinert et al, 2005). Skarn deposits range in size from a few million to 500 million tonnes and are globally significant, particularly in the American Cordillera. They can be stand- alone copper skarns, which are generally small, or can be associated with porphyry copper deposits and tend to be very large. The North Star deposit is large, at the upper end of the range of size for skarn deposits, and is likely associated with a mineralized porphyry copper system that has not been discovered.

Copper skarns generally form in calcareous shales, dolomites and limestones peripheral or adjacent to the mineralized porphyry. Copper mineralizing hydrothermal fluids are focused along structurally complex and fractured rocks and convert the calcareous shales and limestones to andradite rich garnet assemblages near the intrusive body, and to pyroxene and wollastonite rich assemblages at areas more distal to the stock. Retrograde hydrothermal fluids produce actinolite-tremolite-talc-silica-epidote-chlorite assemblages that overprint earlier garnet and pyroxene. The mineralization is typically pyrite -chalcopyrite-magnetite proximal to the mineralizing porphyry and chalcopyrite-bornite more distally from the body. The copper-gold porphyry and skarn model by Sillitoe (1989) is being used as a conce ........

Excelsior proposes to use the In-Situ Recovery (ISR) method to extract copper from oxide mineralization located within the North Star deposit. ISR was chosen based on the fractured nature of the host rock, the presence of water saturated joints and fractures within the ore body, copper mineralization that preferentially occurs along fracture surfaces, the ability to operate in the vicinity of Interstate 10, and to avoid the challenges of open pit mining in an area with alluvium overburden thickness ranging from approximately 300 feet to 800 feet.

In the ISR process, a low pH raffinate solution (“lixiviant”) is injected into the ore body via a series of injection wells. As the lixiviant migrates through the joints and fractures within the mineralized bedrock, copper is dissolved. This pregnant leach solution (PLS) is recovered by a series of recovery wells that surround each respective injection well.

The PLS is pumped to the surface where the copper is stripped from the solution using the solvent extraction/electrowinning (SX-EW) process. The SX-EW process begins with the SX plant extracting and concentrating the dissolved copper from the PLS, after which the EW plant reduces the concentrated copper to copper cathode. Once the copper is recovered by SX, the barren solution is re-acidified with sulfuric acid to create new lixiviant which is pumped back to the well field and re-injected. The total volume of lixiviant injected and PLS extracted will remain ........

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