New Cornelia mine
Encyclopedia
The New Cornelia mine is a currently inactive open-pit copper
Copper
Copper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...
mine in Pima County, Arizona
Pima County, Arizona
-2010:Whereas according to the 2010 U.S. Census Bureau:*74.3% White*3.5% Black*3.3% Native American*2.6% Asian*0.2% Native Hawaiian or Pacific Islander*3.7% Two or more races*12.4% Other races*34.6% Hispanic or Latino -2000:...
, United States. It was the only productive mine in the Ajo mining district, and is located just outside the town of Ajo
Ajo, Arizona
Ajo is a census-designated place in Pima County, Arizona, United States. The population was 3,705 at the 2000 census. Ajo is located on State Route 85 just from the Mexican border. It is the closest community to Organ Pipe Cactus National Monument....
, which was built as a company town to serve the New Cornelia miners. The roughly circular pit is one and a half miles across at its widest point, and 1,100 feet deep at the center.
History, archaeological mining history
Native Americans had long mined surface exposures of copper veins near the New Cornelia for pigments: red copper oxide and green copper carbonate. Spanish miners are known to have at least excavated test shafts in the area by 1750, but the amount of copper produced is not known. Americans claimed the location in 1854, and shipped a few loads of selected ore to SwanseaSwansea
Swansea is a coastal city and county in Wales. Swansea is in the historic county boundaries of Glamorgan. Situated on the sandy South West Wales coast, the county area includes the Gower Peninsula and the Lliw uplands...
, Wales
Wales
Wales is a country that is part of the United Kingdom and the island of Great Britain, bordered by England to its east and the Atlantic Ocean and Irish Sea to its west. It has a population of three million, and a total area of 20,779 km²...
, but high transportation charges left little or no profit, and the mine was abandoned.
Development of the property was delayed because of its remote desert location. The low-grade copper ore could not be economically shipped to a smelter, and had to be concentrated at the site. The Cornelia Copper Company was organized by St. Louis
St. Louis, Missouri
St. Louis is an independent city on the eastern border of Missouri, United States. With a population of 319,294, it was the 58th-largest U.S. city at the 2010 U.S. Census. The Greater St...
businessmen in 1900 to develop the property. However, early owners fumbled in their search for a suitable treatment process, and fell victim to “process men.” In 1906 the owners contracted with “Professor” Fred McGahan to build his unique “vacuum smelter” to treat the ore. The following year the company had McGahan indicted for obtaining money under false pretenses. It then arranged with another inventor to build facilities to treat the ore by the unproven “Anderson Process,” which proved just as useless as McGahan’s process. A US Geological Survey author later described these processes as "... among the most bizarre ever to have been floated in American mining." Mining commentator Horace Stevens wrote:
- ”The officers of the Cornelia are residents of St. Louis and vicinity, of excellent local standing, and perfectly sincere in their operations, but are totally lacking in practical knowledge of the copper business, and prone to overmuch experimentation with new processes.”
The company reorganized as the New Cornelia Mining Company. In 1911, the Calumet and Arizona Mining Company, which already had a major operation in Bisbee
Bisbee, Arizona
Bisbee is a city in Cochise County, Arizona, United States, 82 miles southeast of Tucson. According to 2005 Census Bureau estimates, the population of the city was 6,177...
, took an option to buy 70 percent of New Cornelia stock. Calumet and Arizona confirmed the existence of a large copper carbonate orebody, and exercised the option. It then found a practical way to treat the ore, and located a sufficient source of water several miles north. A pilot plant began operation in 1915, and a railroad connection via Gila Bend
Gila Bend, Arizona
Gila Bend , founded in 1872, is a town in Maricopa County, Arizona, United States. The town is named for an approximately 90-degree bend in the Gila River, which is close to but not precisely at the community's current location...
was completed in 1916.
Full-scale mining using steam shovels was started in 1917, making the New Cornelia the first large open pit mine in Arizona. Mining and treatment of the underlying but lower-grade copper sulfide orebody began in 1924.
New Cornelia came under the ownership of Phelps Dodge in 1931 when Calumet and Arizona merged with Phelps Dodge
Phelps Dodge
Phelps Dodge Corporation was an American mining company founded in 1834 by Anson Greene Phelps and William Earle Dodge, Sr.. On March 19, 2007, it was acquired by Freeport-McMoRan and now operates under the name Freeport-McMoRan Copper & Gold Inc.-History:...
.
The mine was shut down in 1983 due to low copper prices. Copper production from the mine totaled 6.304 billion pounds of copper, worth about US$20.8 billion at the 2010 copper price of $3.30/pound.