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Gunnison Copper Project

Project Highlights


Technical Report

Click here for the complete NI 43-101 Technical Report, Prefeasibility Study on the Gunnison Property - January 2014

Project Highlights

  • Measured and Indicated Mineral Resources of 3.91 billion pounds (683 million tons at 0.29% copper) which includes 1.21 billion pounds Measured (158 million tons at 0.38% copper) and 2.70 billion pounds Indicated (525 million tons at 0.26% copper). The Mineral Resources are inclusive of Mineral Reserves. Mineral Resources and Reserves are at a 0.05% cut-off.

  • On July 7, 2015 Excelsior announced an upgrade to the mineral resource. The North Star deposit now contains Measured and Indicated Mineral Resources of 4.95 billion pounds (866 M tons at 0.29%). There is an additional inferred resource of 0.58 billion pounds (173 M tons at 0.17%).


The Gunnison Property, 2,461 hectares in size, is located 65 miles southeast of Tucson Arizona within the copper porphyry belt.  The towns of Benson and Wilcox are located nearby and can provide skilled labour for the Gunnison Project.  The property is ideally located with access to electrical power on the property, previously developed infrastructure, and supported by an abundant water supply.  The Gunnison Property neighbours several other copper mining developments because it is located within the porphyry belt for copper.

    Location Map

Positive Prefeasibility Study

The PFS was completed by M3 Engineering & Technology Corporation ("M3") of Tucson, AZ and is effective as of January 13, 2014. For more information please refer to the Technical Report.

Highlights of the North Star Gunnison Copper Project PFS “Acid Plant” option include:
  • Pre-tax NPV of US$1.24 billion (after-tax US$0.824 billion) at a 7.5% discount rate (using a copper price of US$2.75/lb)
  • Pre-tax IRR of 59.7% (after-tax 44.7%)
  • Pre-tax payback period of 1.8 years (after-tax 2.4 years)
  • Initial estimated capital cost (excluding sustaining capital) of US$284.84 million
  • Average life-of-mine operating costs of US$0.69 per pound
  • Other costs of US$0.13 per pound, including Royalties of US$0.029 per pound
  • Annual production rate of 110 million pounds of copper for the first 14 years, then declining for a 20 year mine life, with a total of 1.682 billion pounds of copper produced over the life of the mine
  • Based on an initial annual production rate of 110 million pounds, the PFS indicates that including an Acid Plant as a component of the project, generates a pre-tax NPV of US$1.24 billion, at a cash flow discount rate of 7.5%. The pre-tax IRR for this option is 59.7% with a payback period of 1.8 years. On an after-tax basis, the PFS shows an NPV (7.5% discount rate) of US$824.17 million, IRR of 44.7% and a payback period of 2.4 years.
  • Without an Acid Plant, the project still has a significant pre-tax NPV7.5 of US$1.06 billion and an IRR of 61.3%, (after-tax NPV 7.5% discount rate of US$720.4 million and an IRR of 46.1%). The after-tax analysis is based on a number of assumptions which will be fully set out in the Report. The level of accuracy of the PFS is considered to be +/-20%.


The PFS illustrates very strong project economics in both the "Acid Plant" and "Non-Acid Plant" scenarios, with the Acid Plant option adding an additional US$174.2 million to the project NPV.


2014 - 15 Feasibility Work Program

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Metallurgical Box Tests

Designed to simulate a mineralized fracture, the results from these box tests will provide relative acid consumption rates, and provide information on the kinetics of leaching.

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QP Statement

Excelsior’s exploration work on the Gunnison Property is supervised by Stephen Twyerould, Fellow of AUSIMM, President and CEO of Excelsior and a Qualified Person as defined by NI 43-101. Unless otherwise indicated, Mr. Twyerould has reviewed and is responsible for the technical information contained in this website.