El Boleo

El Boleo is a copper-cobalt-zinc-manganese deposit located adjacent to the port city of Santa Rosalía, Baja California Sur in Mexico. It includes a historic open pit copper mine, as well as underground workings. Mining began in the 1860s, and continued, off and on, until the 1980s. The property is currently under development by a consortium of Korean companies led by Korea Resources Corporation. Preliminary underground mining began in 2012. The $1.75 Billion project is scheduled for completion in 2013.

The discovery of the copper ore in the region is historically credited to a rancher named José Rosas Villavicencio in 1868. Minor mining activities were carried out on site by Mexican and German operators until 1885. But the small scale of the operation and the desolate location made the enterprise only marginally economic.

El Boleo was first operated, on a large commercial scale, in 1885 by the French company Compagnie du Boleo which obtained control of the property and began mining, after receiving an extensive concession and 70-year tax exemption granted by Mexican president Porfirio Diaz. Diaz apparently hoped that the mine would create a development zone in the arid and unpopulated region. 1885 is also considered the official date of the town's foundation.

The extraction of ore from the mines was labour-intensive. Chinese, Japanese, Yaqui Indians and Mestizos were brought in to work in the mine. It has been reported that many died of illness or accidents associated with the poor working conditions.

As the ore was extremely rich, (apparently a complex mixture of oxides and sulfides of up to 15% Cu) it could be fed directly to the smelter without pre-processing other than crushing. There were 7 relatively small reverberatory furnaces in the smelter and, in the 1930s, a pair of Peirce-Smith converters^[] were added to produce blister copper (98% copper). Due to the complex metallurgy, no attempt was made to extract the cobalt, zinc, and manganese. The company created an artificial harbour from the slag of the smelter, which still endures almost unchanged to the present day.

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