The Mission deposit is a porphyry copper skarn deposit located southwest of the city of Tucson in Pima County, Arizona. A series of Paleozoic sedimentary rocks.

Mineralization is a skarn-related copper porphyry deposit with seams and disseminations of copper carbonates and sulfides with minor zinc, lead and molybdenum minerals in a pyrometasomatic deposit in altered, complexly folded, and faulted Paleozoic limestone and Triassic sedimentary and volcanic formations intruded by Laramide and Tertiary intrusives. There is a thin secondary enrichment zone. The host rock unit is the Scherrer Formation.

The Mission Complex, an open-pit mine composed of the Mission, Eisenhower, Pima, Mineral Hill and South San Xavier properties and the nearby North San Xavier mine.

The Mission Complex currently consists of an open pit copper and molybdenum mine that involves drilling, blasting, loading, and haulage activities to both waste rock dumps and crushers. The waste rock is not processed further.

The current pit, 2.5 miles long by 1.5 mile wide and 1,200 feet deep, is situated on 20,000 acres. Benches are 40 feet high.

The complex consists of a mine and two concentrators (Mission Molienda Norte and Molienda Sur), which have a combined production capacity of 52,600 metric tons per day.

The Facility is currently processing approximately 53,000 tons of ore per day. Future production rates are likely to depend on copper prices. Ore is crushed via the primary gyrotory crusher, rod mill, and ball mill. The ground ore is pumped as a slurry to froth flotation cells, where chalcopyrite is separated from non-copper bearing minerals. Lime, xanthates (a biodegradable additive that serves as a collecting agent), pine oil (a frothing agent), and methyl isobutyl carbonal are added to the mixture to facilitate separation of the copper mineral. In the flotation stage, the chalcopyrite attaches to the air bubbles and is skimmed off. The first initial processing stage, called “roughing,” removes approximately 88% of chalcopyrite. The skimmed materials from the roughing stages are re-ground and sent to second ........