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).

The North Star deposit is covered by un-mineralized basin fill, varying between 300 and 800 feet in thickness. The mineralized Paleozoic host rocks below the basin fill strike approximately north-northwest and dip 20° to 45° eastnortheast. Baker (1953) recognized three sets of faults in the Johnson Camp area and similar faults have been interpreted in the North Star area. These faults include the “Northeaster” (N10° to 30°E striking; 70° to 75° dip to the SE), “Easter” (N60°E to S60°E striking; 30° to 50° S and higher angle reverse faults dipping 75°S) and “Northwestern” orientations (N15° W strike; steep E or W dip). Only minor displacements are thought to have occurred in the North Star area; however numerous sheared and brecciated faults, generally filled with copper-oxide mineralization, cut through the deposit.

The Paleozoic host rocks have been intruded by the Texas Canyon quartz monzonite along the western margin of the deposit. The intrusion has formed wide zones of calc-silicate and hornfels alteration, as well as extensive low-grade copper sulfide mineralization within the Paleozoic rocks. Metamorphic alteration grading outward from the stock includes garnet-wollastonite-idocrase, diopside, tremolite and chlorite-talc (Kantor, 1977) (Figure ........

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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