El Teniente

According to legend, the El Teniente mine was discovered in the 1800s by a fugitive Spanish official. Exploitation of the resource began in 1819. The best ore was mined manually in what would be called the Fortuna sector, and transported out of the mine by pack animals, such as ponies and mules. It was worked until 1897, when the high-grade ore was exhausted.{{cite book|url=https://books.google.com/books?id=GnDYrDVmJI4C&dq=distance+between+Sewell+and+El+Teniente&pg=PA89|title=Investment in Chile |last1=Bohan |first1=Merwin Lee|last2= Pomeranz|first2=Morton |page=89|location= Washington, DC |publisher=US Bureau of Foreign Commerce |date=1960}}

In 1904 William Braden (an engineer from New York City, United States){{cite book|last=Fox Przeworski|first=Joanne|title=The decline of the copper industry in Chile and the entrance of North American Capital|year=1978|page=25|url=https://books.google.com/books?id=Xn5jSP46ZNQC&dq=el+teniente+mine+&pg=PA25|accessdate=2009-04-10 | isbn=978-0-405-13379-4 | publisher=Ayer Publishing}} and E.W. Nash formed the Braden Copper Company. They built a road for carts and a concentrating plant, which was in operation by 1906.{{cite book|chapter=51|title=Underground Mining Methods|editor=W. A. Hustrulid, Richard C. Bullock|publisher=Society of Mining Engineering|page=417|chapter-url=https://books.google.com/books?id=N9Xpi6a5304C&dq=el+teniente+mine+&pg=PA417|access-date=2009-04-10 | isbn=978-0-87335-193-5}}{{Cite book |author=Charles Caldwell Hawley |title=A Kennecott Story |publisher=The University of Utah Press |year=2014 |pages=104–105}}

In June 1910, Guggenheim Exploration took control of the mine and provided financing.{{rp|146–147}} In 1916 Braden became a subsidiary company of Kennecott Copper Corporation,{{cite news|url=https://www.nytimes.com/1967/04/14/archives/chile-acquires-51-of-el-teniente-mine.html|title=CHILE ACQUIRES 51% OF EL TENIENTE MINE|date=April 14, 1967|website=The New York Times|pages=Business & Finance 59|access-date=2009-04-10}} which was based in Utah.

Chileans have referred to such large-scale copper mining operations as La Gran Minería del Cobre (a major copper mine). Before nationalization, these operations generated a large proportion of the foreign currency which the country received.

In 1945 there was a disaster at El Teniente mine, resulting in the deaths of 355 men and injury to 747 more. It was the largest mining accident in Chilean and has the highest death toll in world history associated with metal extraction. Some 1,000 miners were down in the pits when the fire started in a nearby warehouse. Dense smoke spread in the underground tunnels. Most of the dead and injured suffered carbon monoxide poisoning. Emergency exits were not well marked. In Chile, this incident is known locally as the Smoke Tragedy ({{langx|es|La tragedía del humo}}).

In 1967 the Chilean government bought a 51% stake in the mine and founded Sociedad Minería El Teniente. Under this agreement Kennecott built a new concentrator, and the mine expanded production to {{convert|63000|t|ST|abbr=on}} per day.

On July 11, 1971, President Salvador Allende ordered the Chilean nationalization of copper,{{cite news|url=https://www.bloomberg.com/apps/news?pid=20601088&sid=aj0Zp.Jhyl1s&refer=muse|title=Copper Passion Drives Trader on Quest for Antiques (Update1) |last=Craze|first=Matthew|date=April 11, 2007|publisher=Bloomberg|access-date=2009-04-10}} in an effort for the country to gain more benefit from the mines. Corporación Nacional del Cobre de Chile (known as Codelco) was formed, and El Teniente became a state-owned operation. The Chilean government paid Kennecott $92.9-million for the property.{{cite news|url=https://select.nytimes.com/gst/abstract.html?res=FB071FFF3A5C1A7493C6A9178AD85F468785F9&scp=3&sq=El%20Teniente&st=cse|title=KENNECOTT SEEKS PAYMENT BY CHILE; Asks Government to Honor Installment on Note KENNECOTT SEEKS PAYMENT BY CHILE|last=Gerd|first=Wilcke|date=January 4, 1972|website=The New York Times|access-date=2009-04-10}}

The mine increased production to {{convert|100000|t|ST|abbr=on}} of ore per day, and in 2006 the mine produced over {{convert|418000|t|ST|abbr=on}} of copper.{{cite web|url=http://www.codelco.com/la_corporacion/division_elteniente_ficha.asp |title=Ficha técnica División El Teniente |publisher=Codelco.com |access-date=2010-10-22 |url-status=dead |archiveurl=https://web.archive.org/web/20110726132440/http://www.codelco.com/la_corporacion/division_elteniente_ficha.asp |archivedate=2011-07-26 }}

The Vancouver, British Columbia-based, Canadian company Amerigo produces both a copper and molybdenum concentrate from El Teniente's tailings. It has been granted the right also to treat higher grade tailings from a large, abandoned tailings impoundment near the El Teniente property.{{cite news|title=Amerigo will generate own power to cut Chile costs|last=Hill|first=Liezel|date=27 March 2009 |publisher=Creamer Media's Mining Weekly}}

The copper ore deposits are those of a typical copper porphyry and associated alteration-mineralization. These altered zones include chalcopyrite, pyrite, bornite and molybdenite as hypogene minerals and chalcocite as a supergene mineral.{{cite journal|last1=Camus|first1=Francisco|title=Geology of the El Teniente orebody with emphasis on wall-rock alteration|journal=Economic Geology|date=1975|volume=70|issue=8|pages=1341–1372|doi=10.2113/gsecongeo.70.8.1341}} The ore body surrounds the Braden Pipe in a continuous ring with a width of 2000 feet. The pipe is a geologic structure in the shape of an inverted cone, having a surface diameter of 4000 feet, and consisting of post-pipe breccia called the Braden Formation. The boundary of the pipe is marked by this post-pipe breccia and a pre-pipe breccia forming a belt up to 200 feet wide. "The Braden Pipe was a center of strong mineralization and structural weakness before the pipe was formed." Copper mineralization and pipe formation occurred in the Pliocene. Ore was originally mined from the Fortuna orebody at the southwest quadrant starting in 1906. Since 1922, the larger Teniente orebody has also been mined on the east side. "The best grade of ore is found in altered andesite or in andesitic flow breccia adjacent to the pre-pipe breccia."{{cite journal|last1=Howell|first1=Fred|last2=Molloy|first2=John|title=Geology of the Braden orebody, Chile, South America|journal=Economic Geology|date=1960|volume=55|issue=5|pages=863–905|doi=10.2113/gsecongeo.55.5.863}}

Mineralization at El Teniente is thought to be indebted to its position at the intersection of two large fault systems. This favoured the rise of magma and the subsequent circulation of mineral-rich fluids.{{cite journal |last1=Piquer Romo |first1=José Meulen |last2=Yáñez |first2=Gonzálo |last3=Rivera |first3=Orlando |last4=Cooke |first4=David |date=2019 |title=Long-lived crustal damage zones associated with fault intersections in the high Andes of Central Chile |url=http://www.andeangeology.cl/index.php/revista1/article/view/V46n2-3106/pdf |journal=Andean Geology |volume=46 |issue=2 |pages=223–239 |doi=10.5027/andgeoV46n2-3108 |access-date=June 9, 2019|doi-access=free }}

As of 2007 Codelco employed 17,000 direct-hire company employees and 28,000 contract employees across all their operations.{{cite news|title=Chile: Copper Miners Protest Subcontracting Practices|last=Estrada|first=aniela|date=31 July 2007|publisher=Inter Press Service}} There have been multiple labour disruptions at the El Teniente mine, where about 5,000 workers produce the ore.

In 1983 El Teniente and two other Codelco mines closed when approximately 13,000 workers voted to strike "indefinitely" in protest of a union leader's arrest for calling for an end to military rule in Chile. In total among the three mines, at least 3,300 workers and 37 labour leaders were fired for participating in the strike.{{cite news|url=http://nl.newsbank.com/nl-search/we/Archives?p_product=PI&s_site=philly&p_multi=PI&p_theme=realcities&p_action=search&p_maxdocs=200&p_topdoc=1&p_text_direct-0=0EB295AEFB00DC54&p_field_direct-0=document_id&p_perpage=10&p_sort=YMD_date:D&s_trackval=GooglePM|title=Army Takes Over 2 Mines as Workers Strike in Chile|date=June 19, 1983|website=The Philadelphia Inquirer|pages=A07|access-date=2009-04-10}}

Contract workers went on strike at Codelco mines in 2008. El Teniente and two other Codelco mines were closed, El Teniente for the shortest length. Company employees continued to work; however, striking workers closed access to the mines and threw stones at buses transporting employees from the mine to the town of Rancagua. At least one employee was injured; he was hit by a metal object thrown by a protester on the highway leading to the mine.{{cite news|url=https://www.bloomberg.com/apps/news?pid=20601086&sid=aPz6Dpn99pRg&refer=news|title=Codelco, Striking Workers May End Dispute Soon (Update1) |last=Matthew|first=Craze|author2=Sebastian Boyd|date=April 23, 2008|publisher=Bloomberg|access-date=2009-04-10}}

• Escondida
• Chanarcillo
• Los Pelambres mine
• Potrerillos, Chile
• Chuquicamata
• El Salvador mine
• Mining in Chile

{{Commons category|El Teniente}}

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Category:Copper mines in Chile

Category:Mines in O'Higgins Region

Category:Underground mines in Chile

Category:Codelco