The nationalization of the Chilean copper industry, commonly described as the Chileanization of copper () was the process by which the Chilean government acquired control of the major foreign-owned section of the Chilean copper mining industry. It involved the three huge mines known as 'La Gran Mineria' and three smaller operations. The Chilean-owned smaller copper mines were not affected. The process started under the government of President Carlos Ibáñez del Campo, and culminated during the government of President Salvador Allende, who completed the nationalization. This "act of sovereignty" was the espoused basis for a later international economic boycott, which further isolated Chile from the world economy, worsening the state of political polarization that led to the 1973 Chilean coup d'état. The mines involved in the nationalization By the late 1950s, the three principal copper mines in Chile were Chuquicamata, El Salvador, and El Teniente. Chuquicamata and El Salvador were owned by the Anaconda Copper Company and El Teniente was owned by the Kennecott Copper Corporation. The La Exotica mine, an adjunct of Chuquicamata, was added to these big mines in 1966.These large mines were mainly self-contained and self-sustaining settlements with their own cities to house their workers, their own water and electrical plants, their own schools, stores, railways, and even in certain cases their own police forces. Three other mines were eventually nationalized, Cerro de Pasco's Andina operation, which went to Codelco, and the two mines, Los Bronces and El Soldado, owned by Peñarroya's Disputada de las Condes, which were bought by ENAMI. Evidently these mines did not fit in with ENAMI's plans and Disputada de las Condes was subsequently sold (at a substantial profit) to Exxon Minerals. Second stage of nationalization On June 26, 1969, President Eduardo Frei Montalva signed an agreement with the Anaconda Copper Company, the Kennecott Utah Copper company, and the Cerro company (which was afterwards ratified by Congress). In this agreement, the government acquired the 51% of the Kennecott’s shares and 25% of the shares in both Anaconda and Cerro, allowing the U.S. to maintain some level of control in this economic sector. This process was known as "negotiated nationalization", and was designed to avoid a conflict with international investors (and ultimately with the United States) and to allow for the acquisition of the technical, financial and marketing knowledge of the multinationals. A similar process was used to acquire a dominant ownership over the rest