Pima Mine - Pima County
Where: South of Tucson near Green Valley just off I-19
Travel Conditions: Paved road can be travelled by any vehicle.
Operation Dates: 1877 to present
Description: Mine Tales: Pima Mining district grew from humble beginnings
September 23, 2013 12:00 am - By William Ascarza Special to the Arizona Daily Star
Located 18 miles south of Tucson near the Sierrita Mountains and organized in 1877, the Pima Mining District had humble beginnings with several small mining camps.
Deposits of copper, silver, lead, zinc and later molybdenum drew an interest to the area, including early operations conducted by the Emperor Copper Co. (1883), the Azurite Copper and Gold Co. (1897), Twin Buttes Mining and Smelting Co. (1903), Mineral Hill Consolidated Co. (1906) and ASARCO (1915).
Originally worked by the Spanish for gold and silver in the 18th century, the remains of arrastras and shallow shafts were evident during early American development. Several noteworthy operations established in the district included the Mineral Hill, San Xavier and Twin Buttes mines.
Early on, ores were treated at sites including a local smelter with a 30-ton daily capacity. The smelter operated for a year followed by other short-lived smelters, including a 150-ton smelter built by the Pioneer Smelting Co., a mile-and-a-half west of Sahuarita at Camp Corwin in 1912.
Shipments of concentrates from later mills established around Sahuarita were also sent to smelters at Hayden, El Paso and, briefly, Sasco.
Several small camps operated in the area, including one named Azurite, another called San Xavier
"later changed to Olive for a nearby mine" and Twin Buttes.
Azurite, located a half-mile south of the Mineral Hill Mine, reached a population of 125 by the turn of the century. The high-grade lead-silver ores acquired from the San Xavier Mine before 1900 made it an attractive investment, having yielded a value of around $750,000.
Four miles farther south was the Twin Buttes Camp that included a cluster of buildings housing a bunkhouse, a butcher shop, a company store and a mess hall. The 10-mile Twin Buttes Railroad carried ore from the Senator Morgan Mine at Twin Buttes to the town of Sahuarita.
A line also connected Sahuarita with the Southern Pacific Railroad in Tucson. Depending on the profitability from local mines, the Twin Buttes Railroad operated from 1906 to the late 1920s, finally closing when mining in the district declined.
The Pima Mining District underwent a revival in 1950 when Banner Mining Co. bought the properties, including the Mineral Hill and Daisy mines, which were a half-mile from each other. Banner subsequently conducted mining and milling operations at the site.
The Pima Mining Co. and the Eagle-Pitcher Co. were also involved in mining ventures in the area.
The United Geophysical Co., using sensitive instrumentation, was responsible for the discovery of ore bodies that led to the establishment of open-pit mining operations at Twin Buttes in the 1960s. In 1962, the copper production from these early mines contributed to Pima County’s title of top copper producer in Arizona.
Closed in 1994, the Twin Buttes Mine was acquired in 2009 by Freeport McMoRan, which later carried out a drilling program to determine the size and quality of the deposit. The Twin Buttes Mine is estimated to contain 700 million tons of copper and molybdenum mineralization with a copper grade of 0.43 percent. Its future as an active mine depends on a sustainable high market price of copper and adequate water supply to run its operations.
William Ascarza is an archivist, historian and author of five books, including "Southeastern Arizona Mining Towns" and "Zenith on the Horizon: An Encyclopedic Look at the Tucson Mountains from A to Z," available at Antigone Books, Cat Mountain Emporium, the Arizona-Sonora Desert Museum and the Arizona Geologic Survey’s Arizona Experience Store. Email him at mining@azstarnet.com
Sources: Arizona Geology Magazine 2010 Arizona Mining Review; "Awake the Copper Ghosts! The History of the Banner Mining Company and the Treasure of Twin Buttes," Banner Mining Company (William D. Kalt Jr., 1968); Mineral and Water Resources of Arizona. Arizona Bureau of Mines Bulletin 180, University of Arizona, 1969; "The Olive and Mineral Hill Camps of Pima County, Arizona," Mining Reporter May 31, 1906; "Ore Deposits of the Sierrita Mountains, Pima County, Arizona." Contributions to Economic Geology Bulletin 725 (F.L. Ransome, 1922); "Ghost Towns of Arizona" (James E. and Barbara H. Sherman, 1969.
What you will see today: Today the open pit mine is still in operation and provides guided tours starting from the ASARCO Mineral Discovery Center. The tour takes you through the entire process of getting copper from the rocks in the mine. Views of the open pit mine and the equipment used to process the ore are part of the tour. This is a comprehensive view of the mine and it's operations.
What you will see today: Today the open pit mine is still in operation and provides guided tours starting from the ASARCO Mineral Discovery Center. The tour takes you through the entire process of getting copper from the rocks in the mine. Views of the open pit mine and the equipment used to process the ore are part of the tour. This is a comprehensive view of the mine and it's operations.
Comments: The Discovery Center provides a great insight to the processes used to extract the coppper from the ore mined from the open pit. It is a great opportunity to tour the mine and see the complete operation from extracting the ore from the ground to processing the copper from the rock. This is a great opportunity and learning experience along with exposure to the mining equpiment and machinery.
Minerals Mined: Primary mineral is copper with silver, gold,lead and molybdenum being secondary
Acknowledgement: Arizona Daily Star, The Pima Mine Story