Oracle Ridge mine in the Santa Catalina Mountains may re-open next yearby Jonathan DuHamel on May. 29, 2012, under Geology
The Oracle Ridge mine is a small, underground copper mine in the Santa Catalina Mountains about 3 miles northeast of, and downhill from, Summerhaven. This mine is on private property within Coronado National Forest. The mine was operated intermitently, most recently from 1991-1996. See location map below. The mine is being developed by a junior Canadian mining company, Oracle Ridge Copper (project website).
The ore is predominantly bornite ( Cu5FeS4) hosted by limestone. Chalcopyrite ( CuFeS2) occurs in the lower reaches. Ore grade is considerably higher than that at the open pit mines in the area. The ore also contains silver and gold.
Exploration in the area may have begun as early as 1870 and the first major operation dates from 1881 according to the Department of the Interior. The Oracle Ridge mine is principally a contact metamorphic skarn similar to the Rosemont deposit.
The company anticipates employing about 200 people, running the mine 24 hours per day, 365 days per year. The anticipated mine life is 11 years.
The ore will be mined and crushed underground, then conveyed to a plant immediately outside the mine. The mine will produce 140 tons of concentrate (about 30% copper) a day which will be trucked off the mountain and transported to a smelter. The company has not announced which smelter, but ASARCO’s Hayden smelter is the closest.
Tailings will be contained by a double-lined, dry stack method with water reclaimed and recycled. The old tailings will be incorporated in the new tailings piles on private land. The entire operation would be contained within 45 acres. The water supply will come from underground workings and wells.
The photo below shows the mine area. The gray areas are tailings from past operations. The company claims that new operations would not increase the existing footprint.