Mission Mine

Mission Mine and Mineral Discovery Center - Asarco Mineral Discovery Center

Useful Information

photography — Tailings, Mission Mine. Public Domain.

Location:	Mineral Discovery Center, Sahuarita. From Tucson Interstate 19 south to Exit 80, Pima Mine Road.
Open:	Mineral Discovery Center: All year Tue-Sat 9-17. Mine Tour: All year Tue-Sat 9:30, 11, 12:30, 14, 15:30. [2008]
Fee:	Mineral Discovery Center: free. Mine Tour: Adults USD 8, Children (5-12) USD 5, Children (0-4) free, Seniors (62+) USD 6. Groups (+): Adults USD , Children () USD . [2008]
Classification:	Adults USD 8, Seniors USD 6, Children USD 5. [2008]
Light:	n/a
Dimension:	L=3,200 m, W=2,800 m, VR=400 m.
Guided tours:
Photography:
Accessibility:
Bibliography:
Address:	ASARCO Mineral Discovery Center, 1421 W Pima Mine Road, Sahuarita, AZ 85629 E-mail: Information Line, Tel: +1-520-625-7513. Tour reservations, Tel: +1-520-625-8233.
As far as we know this information was accurate when it was published (see years in brackets), but may have changed since then. Please check rates and details directly with the companies in question if you need more recent info.

History

Geology

The low grade ore contains about 0.67 percent copper, mostly in form of chalcopyrite. Other minerals are azurite and chrysocolla.

Description

Mission Mine is not the biggest open cast mine in Arizona, which actually has at least two of the three biggest holes on Earth. But a depth of 400 meters is definitely a lot, and the good accessibility with regular tours make this mine one of the best mines to visit. The tours start at the ASARCO Mineral Discovery Center, a mining museum operated by the mining company ASARCO. This is also the ticket office and starting point of the mine tours. And like the National Park Visitor Centers it is free. The informational film, the exhibits and the hands on display are a good way to spend the time while waiting for the tour.

The tour is made by modern coaches with overhead monitors which show a short video about the mine and its environmental concerns. The stops include the upper overlook, the main conveyors and primary crushers. The crushers crush the ore into pieces about 20 cm in diameter, then the main mill gradually grind it into a fine powder. The extraction process happens in tanks, where the slurry is mixed with milk of lime, pine oil, alcohol, and potassium amyl xanthate. The mixture is stirred by air which is blown into the tanks and so finally the potassium amyl xanthate sticks to the chalcopyrite particles in the fluid. The chalcopyrite emulsion flows over the rim and is collected. The process increases the content of copper to about 28%, the mud is dried and shipped to the ASARCO smelter in Hayden.