Anaconda Copper
A historic American mining company that became one of the world’s largest copper producers before its acquisition by Atlantic Richfield in 1977.
Last updated August 22, 2026
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Overview
Anaconda Copper was the public-facing identity of a major American mining and metals enterprise headquartered in Butte, Montana. Its corporate history began in 1881, when mining entrepreneur Marcus Daly joined with George Hearst, James Ben Ali Haggin, and Lloyd Tevis to develop the Anaconda silver mine. Copper deposits discovered soon afterward transformed the business from a silver-mining venture into one of the most important copper producers in the United States and eventually the world. The company built an integrated industrial system around the Butte mining district. Its activities included underground and open-pit mining, ore concentration, smelting, refining, metal fabrication, and transportation. In 1883 Daly established a smelter and the company town of Anaconda, Montana, and linked the smelter with Butte through the Butte, Anaconda and Pacific Railway. The enterprise expanded by acquiring neighboring mines and by consolidating competing interests in Butte. During the early twentieth century it became one of the country’s most powerful mining trusts. The company changed names several times. It operated as the Anaconda Gold and Silver Mining Company, Anaconda Mining Company, and Anaconda Copper Mining Company before becoming the Amalgamated Copper Company in 1899. After the consolidation of major Butte interests, the Anaconda name returned in 1915. In the 1920s the company broadened its portfolio beyond Montana, acquiring operations in Mexico and Chile, including the Chuquicamata mine. Chuquicamata became the world’s largest copper mine and for a period generated most of Anaconda’s profits. The company also acquired American Brass and diversified into manganese, zinc, and later aluminum. Anaconda’s fortunes were closely tied to copper prices, industrial demand, and international politics. The company benefited from electrification and wartime demand but suffered heavily during the Great Depression, when copper prices and employment collapsed. From the late 1940s and 1950s it attempted to maintain production through new mining methods and a shift from underground operations to large-scale open-pit extraction, most notably at the Berkeley Pit in Butte. The nationalization of its Chilean and Mexican assets in the early 1970s severely weakened the company. Atlantic Richfield Company acquired Anaconda on January 12, 1977. ARCO later stopped production at the Anaconda smelter in 1980, and mining in Butte ended in 1982 after underground pumping was discontinued and the Berkeley Pit began filling. Following BP’s acquisition of ARCO in 2000, former Anaconda properties became a significant environmental liability. The Butte and Anaconda industrial areas are associated with extensive federal Superfund remediation. Anaconda therefore survives primarily as a historical corporate name and as part of the environmental and industrial heritage of the American West.
History
Marcus Daly purchased the Anaconda silver mine in 1880 after recognizing the potential of the Butte district’s copper-bearing ores. In 1881 he formed a partnership with George Hearst, James Ben Ali Haggin, and Lloyd Tevis to develop the property. The discovery and development of major copper deposits in 1882 changed the enterprise’s direction. Daly constructed a smelter at Anaconda in 1883 and created a company town around it, while the Butte, Anaconda and Pacific Railway connected the smelter with the mines in Butte. As neighboring silver operations declined, the company acquired additional mines and consolidated its position in the district. The enterprise used several names during its early decades, including Anaconda Gold and Silver Mining Company, Anaconda Mining Company, and Anaconda Copper Mining Company. In 1899 it was reorganized as the Amalgamated Copper Company, with backing from Henry Huttleston Rogers and William Rockefeller. The reorganization turned the business into one of the largest industrial trusts of the period. Amalgamated faced competition from other Butte mining interests, especially those associated with F. Augustus Heinze and William Andrews Clark. Through negotiations and acquisitions led in part by John D. Ryan, the company gained near-total control of the Butte mines by the early 1910s. It restored the Anaconda name in 1915. The company’s growth was supported by electrification and high copper demand, but it also attracted scrutiny over market power, stock promotion, and alleged manipulation. The 1920s were a period of international expansion. Anaconda acquired mining operations in Mexico and, in 1923, purchased the Chuquicamata operation in Chile from the Guggenheims. Chuquicamata was then the world’s largest copper mine and became central to Anaconda’s profitability. The company also bought American Brass, expanded into zinc and manganese, and acquired the Giesche enterprise in Upper Silesia. The speculative boom ended dramatically. Anaconda shares were heavily promoted in the late 1920s, and the collapse of the stock price contributed to substantial losses for investors. Copper prices also fell sharply during the Great Depression. The company reduced dividends, cut employment, and struggled with weak demand in both the United States and Chile. World War II restored demand for copper, zinc, and manganese, but postwar conditions again pressured prices and margins. During the late 1940s and 1950s Anaconda attempted to modernize its mining base. The Greater Butte Project used block caving to exploit lower-grade reserves, while the company increasingly moved from underground mining toward open-pit extraction. The Berkeley Pit became the defining example of this transition. Anaconda also entered aluminum reduction in 1955 and employed tens of thousands of people across North America and Chile during the postwar period. International political change brought a decisive crisis. In 1971 Chile nationalized Chuquicamata, depriving Anaconda of a mine responsible for a substantial portion of its profits. The company’s Mexican Cananea operation was also nationalized in 1971. Although compensation followed in the Chilean case, the loss of the foreign assets weakened Anaconda’s financial position. Atlantic Richfield acquired the company in 1977. ARCO closed the Anaconda smelter in 1980 and ended Butte mining in 1982 by stopping the pumps that had kept the Berkeley Pit and underground workings dry. Subsequent environmental contamination from historic mining and smelting led to extensive Superfund activity. After BP acquired ARCO in 2000, those liabilities remained associated with the successor group.
- 1982
Butte mining ends
[1]Mining ended after pumping of the Berkeley Pit and underground mines was discontinued.
- 1977
Acquired by Atlantic Richfield
[1]ARCO purchased Anaconda on January 12, ending its independent corporate history.
- 1971
Chilean and Mexican assets nationalized
[1]Nationalization of Chuquicamata and Cananea removed two major foreign operations from Anaconda’s portfolio.
- 1955
Aluminum added to portfolio
[1]The company expanded beyond copper by entering aluminum reduction.
- 1923
Chuquicamata acquired
[1]Anaconda purchased the Chilean Chuquicamata mine, then the largest copper mine in the world.
- 1922
Expansion into Mexico and Chile
[1]Anaconda acquired mining operations in Mexico and Chile, establishing a major international production base.
- 1915
Anaconda name restored
[1]The company again operated under the Anaconda name.
- 1910
Butte consolidation
[1]Amalgamated had expanded sufficiently to acquire the assets of the other major copper companies operating in Butte.
- 1899
Reorganized as Amalgamated Copper
[1]The enterprise was restructured with participation from Rogers and William Rockefeller.
- 1883
Smelter and company town developed
[1]Daly began construction of a smelter at Anaconda, Montana, and connected it to Butte by railway.
Products and positioning
Large integrated copper and mining enterprise
Metal and mineral product
Copper
Copper was Anaconda’s central product and the basis of its corporate identity. The company extracted copper-bearing ore from underground and open-pit mines, concentrated the ore, and processed it through smelting and refining. Production from Butte and later Chuquicamata made Anaconda one of the leading copper suppliers to industrial markets.
Base metal
Zinc
Zinc became part of Anaconda’s broader base-metals portfolio during its expansion beyond core copper operations. It was associated with the company’s strategy of using mining, processing, and metal-market expertise across several industrial minerals.
Industrial mineral
Manganese
Manganese was another non-copper resource added during Anaconda’s diversification. The business reflected the company’s effort to broaden its exposure to metals needed by manufacturing and heavy industry.
Light metal · 1955
Aluminum
Anaconda entered aluminum reduction in 1955, extending its portfolio into a metal outside its traditional copper and base-metals activities.
Controversies
1982
Environmental legacy of Butte and Anaconda operations
Historic mining and smelting left extensive contamination in the Butte-Anaconda area. The former operations became associated with one of the largest federal Superfund remediation sites in the United States.
1929
Anaconda share speculation and investor losses
Aggressive promotion and trading in Anaconda shares during the late-1920s boom was followed by a severe collapse. Senate investigations later characterized the episode as a major example of financial manipulation that harmed smaller investors.
1912
Pujo Committee investigation of copper-market and stock activity
A congressional investigation examined allegations that William Rockefeller and other figures had profited from efforts to corner or manipulate the copper market and coordinate activity in Amalgamated Copper shares.
Brand decisions
1977
Sale to Atlantic RichfieldM&ABackground
International nationalizations and difficulties in the copper business had weakened Anaconda’s financial position.
Action taken
Atlantic Richfield Company acquired Anaconda on January 12.
Aftermath
Anaconda ceased to operate as an independent major mining company; ARCO later closed its smelter and ended Butte mining.
1971
Response to nationalization of Chilean operationsOtherBackground
The Chilean government nationalized Chuquicamata, a mine responsible for a large share of Anaconda’s profits.
Action taken
Anaconda lost control of the operation and later received compensation from the Chilean government after the change in regime.
Aftermath
The loss materially weakened Anaconda and contributed to its eventual sale to Atlantic Richfield.
1950
Shift toward open-pit mining in ButteStrategyBackground
Declining ore grades and increasing underground-mining costs made traditional vein mining less economical.
Action taken
Anaconda developed the Greater Butte Project and increasingly relied on large-scale open-pit extraction, including the Berkeley Pit.
Aftermath
The approach sustained production for a time but permanently altered the landscape and contributed to the area’s long-term environmental liabilities.
Recent events
Michael Byron resigns from Anaconda Mining's board[2]
Anaconda Mining said Dr. Michael Byron concurrently resigned from the Board, while continuing as a member of the company's Technical Advisory Committee.
Anaconda Mining obtains $3 million revolving credit facility[3]
Reported:
Anaconda Mining obtained a $3 million revolving credit facility with Royal Bank of Canada in July 2021, supported by an Export Development Canada performance guarantee over 75% of the facility limit.
Anaconda Mining shareholders elect directors[4]
Reported:
At its annual and special shareholder meeting, Anaconda Mining reported that all proposed resolutions passed and all nominees listed in the management information circular were elected as company directors.
- Unconfirmed
Anaconda Mining appoints Mary-Lynn Oke to its board[5]
Reported:
Anaconda Mining announced that Mary-Lynn Oke had joined its Board of Directors.
- Unconfirmed
Anaconda Mining announces Maruf Raza's resignation as a director[5]
Reported:
Anaconda Mining announced that Maruf Raza had resigned as a director of the company.
Anaconda Mining extends RBC term-loan amortization[6]
Reported:
Anaconda Mining announced that it had extended the amortization period on its Royal Bank of Canada term loan to April 2022.
Anaconda Mining issues 2020 production guidance[6]
Reported:
Anaconda Mining projected that it would produce and sell between 18,000 and 19,000 ounces of gold in 2020.
Anaconda Mining reports Q3 production and revenue results[7]
Reported:
Anaconda Mining announced Q3 2019 production and financial results, reporting that it sold 4,652 ounces of gold and generated C$8.8 million in metal revenue during the quarter.
Sources8 sources
- 1Anaconda Copperen.wikipedia.org
- 2Michael Byron辞去Anaconda Mining董事会职务albuquerqueexpress.com
- 3Anaconda Mining获得300万加元循环信贷额度finanznachrichten.de
- 4Anaconda Mining 股东选举董事finanznachrichten.de
- 5Anaconda Mining任命Mary-Lynn Oke为董事会成员finanznachrichten.de
- 6Anaconda Mining延长RBC定期贷款摊还期限finanznachrichten.de
- 7Anaconda Mining公布第三季度产量和收入业绩newswire.ca
- 8Anaconda Mining Inc.: Anaconda Mining Appoints Ted Kavanagh to the Board of Directorsfinanznachrichten.de
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