Copper mineralization at Robinson occurs in monzonite porphyry intrusive rocks and associated marginal garnet skarns with varying quantities of pyroxene, magnetite and sulfide which formed in the surrounding upper Paleozoic wall rocks. Early stage potassium silicate alteration in porphyry and skarn mineralization in the wall rocks are typically overprinted by a widespread and commonly intensive high acid alteration event which altered porphyry and some host units to quartz-sericite-pyrite or even advanced argillic assemblages locally. Carbonate host rocks were altered to pyritic marbles or silica pyrite rock containing up to 20 volume percent pyrite locally during this late stage alteration event. Early stage potassium silicate mineralization and skarn was dominated by pyrite and chalcopyrite and is generally low in sulfide with average values ranging from trace to 3%. The high acid alteration event is dominated by up to 10% or 20% pyrite with pyrite:chalcopyrite ratios typically ranging from 10:1 to more than 1,000:1. Where present in the late stage alteration zones, the chalcopyrite may be relict from earlier stage alteration events. Chalcopyrite appears to be the sole hypogene copper mineral, with a few possible exceptions.

Skarn and porphyry ores form much of the current resource and reserve with grades ranging from cutoff (and below) to greater than 1.0%. Metallurgical recoveries in this material are generally good, but are complicated where weathering has par ........

The mine is comprised of 3 large pits: Liberty, TrippVeteran and Ruth. Currently, Ruth is in operation.

Mining is conducted by conventional open-pit methods. It comprises extraction using blasting materials and dump trucks, loading and ore transport to a processing plant.

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The ore is extracted by conventional methods, and is then processed into a copper and gold concentrate, and separately into molybdenum concentrate in a concentrating plant.

The rougher flotation circuit consists of two parallel rows of ten 3,000 cubic feet flotation cells followed by cleaning in six 10' x 38' (3.05 m x 11.58 m) column flotation cells in a parallel configuration. No regrinding is currently being performed. The concentrates are thickened and filtered prior to shipment. The tailings are thickened and are transported by gravity flow to the tailings impoundment.