The Gibraltar open pit mine is a calc-alkalic porphyry copper-molybdenum deposit entirely hosted by the Late Triassic Granite Mountain batholith.

Primary hypogene copper mineralization in the form of disseminated and vein-hosted chalcopyrite predominates at Gibraltar. Minor bornite occurs typically in the east and northeast portions of the deposit. Molybdenite occurs mainly in quartz veins and fractures, and rarely as matrix disseminations. Sphalerite occurs in the Extension deposit, and is especially abundant in the TK Zinc zone farther west. Mineralization in the Granite, Pollyanna, and Connector deposits is hosted in massive to strongly foliated zones. In contrast, mineralization in the Gibraltar, Extension, and TK Zinc zones is almost entirely hosted in strongly foliated shear zones.

Pyrite and chalcopyrite are the principal primary sulphide minerals of the Gibraltar deposits. Fine-grained chalcopyrite, generally barely visible without magnification, accounts for 60 percent of the copper content and constitutes the single most important form of copper mineralization. Most of this fine fraction is dispersed within the phyllosilicate foliation lamellae and forms the uniformly distributed grades of the Gibraltar porphyry-type ores. Coarser grained chalcopyrite usually occurs in quartz veins and shear zones. Pyrite mineralization generally shows some degree of segregation from chalcopyrite and, in the Pollyanna and Granite deposits, pyrite forms a halo ........

The Gibraltar deposits have been developed using open pit, truck and shovel mining methods since 1971. To date (March 2022), mining has progressed in several phases in the Gibraltar, Pollyanna, and Granite pits with future mining to continue in the Pollyanna and Gibraltar pits as well as the undeveloped Connector and Extension pit areas.

Mining operations supply 85,000 tons per day of ore at an average head-grade of 0.25% copper to two primary crushers which in-turn feed the two concentrators. During the 23-year mine life, a total of 699 million tons of sulphide ore, 17 million tons of oxide ore and 1,667 million tons of waste will be mined from the reserve pits at a strip ratio of 2.4. An additional 6 million tons of stockpiled ore will be processed.

For strategic and operational reasons surplus ore is stockpiled at various times during the mine life and for various amounts of time prior to processing. Waste rock is stored in various waste rock storage facilities next to the pits, as well as in previously mined pits after mining of those pits is complete. Suitable overburden waste is salvaged and stored separately for use in reclamation.

Pit Design
All the pits in the reserve plan are designed with a bench height of 50 ft, a bench face angle of 65 degrees. Safety berms are a minimum of 27 ft wide and are increased to achieve inter-ramp wall angles presented in Section 15 of this report. Haul ramps or 60 ft wide geotechnical safety berms ........

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Sulphide ore is processed at a design rate of 85,000 t/day through two bulk concentrators to produce a concentrate which contains copper, silver and molybdenum values. The bulk concentrate from both facilities is combined and processed through a single molybdenum flotation plant. The molybdenum concentrate from this plant is dewatered and bagged, and subsequently shipped to market. The underflow from this plant is the final copper concentrate which includes silver as a by- product. The copper concentrate is dewatered and shipped in bulk to market.

A solvent extraction and electrowinning plant processes leachate from oxide waste dumps to produce a copper cathode product. This system is operated intermittently as conditions allow.

Bulk Concentrator #1
Flotation feed is pumped to two parallel rougher flotation circuits, each consisting of five 160m3 flotation vessels. Flotation tailings are then pumped to a storage facility. Rougher concentrate from the parallel ........