Cortez Gold Mine - Region History

Region History

The Cortez Mountains has been mined since 1862, with silver being the primary commodity the 1940s. The Gold Acres operation in the Cortez Mountains included open pit and underground mines in the 1930s and 1940s. Cortez Gold opened in 1968 and production ended in 1976. The United States Bureau of Mines built a pilot plant in 1969 which would made heap leaching for gold in commercially viable by 1971. The low grade ore and dump material from the Gold Acres operation was then heap leached. The Cortez mill was reopened as the price of gold increased in the early 1980s, feed for the mill was provided by the nearby Horse Canyon deposit between 1983 and 1987. Further exploration of the region was carried out by Cortez Joint Venture which involved Placer Dome and Kenecott ( at the time Kenecott was a BP Minerals subsidiary). The result of the joint venture's exploration was the 1991 discovery of the Pipeline orebody. The Pipeline orebody was located near the Gold Acres operation, instead of being located in the foothills, it was entirely within the Crescent Valley. The Pipeline orebody was much larger than the original orebodies in the region. The entire Pipeline complex contained 23 million ounces of gold between the original orebodies, the Pipeline orebody and the later discoveries of South Pipeline, Crossroads and Gap. The Cortez Joint Venture built the Pipeline Mine and mill in early 1996 following a series of ownership disputes with junior mining companies. Commissioning of the Pipeline mine cost US$250 million, and resulted an annual output between 1998 and 2005 of over one million ounces of gold per year. The Cortez Hills deposit was discovered in 2002, underground development to define the resource limits began in 2006. Barrick Gold acquired 60% in Cortez in 2006 when it purchased Placer Dome for US$10.4 billion, and acquired the remaining 40% from Rio Tinto in March 2008 for US$1.7 billion.