of capital and the property was eventually bought by the American, William Braden, for approximately US$100,000. The same year Braden formed Rancagua Mines, which became the Braden Copper Company, in association with old colleagues from ASARCO, including Barton Sewell. Work started on establishing a mine in 1905 after Government permission had been acquired but progress was slow because of difficulty of access and a hard winter climate. A small gravity plant was soon erected but it was not until 1912 that a flotation plant was erected at Sewell. Control passed to Kennecott in 1915 and it ran the mine until nationalisation in 1971. The present mine The porphyry orebody consists of a stockwork (a network of narrow veins) of mineralised veinlets, mainly in andesitic lavas and tonalite, superimposed by a leached zone and a substantial zone of secondary enrichment, both of very variable thickness. It surrounds a narrow, almost circular ring of tourmaline breccia which in turn surrounds the Braden Chimney, an inverted cone of breccia which was emplaced after the main mineralisation. Reserves and resources are substantial. At the end of 2007 reserves and resources in the mining plan totalled 4,204 million tonnes grading 0.91% copper or 38.3 million tonnes of contained copper. In addition the mine has identified additional resources of 15,827 million tonnes grading 0.46% copper or nearly 73 million tonnes of contained copper though there is no indication how much of this may prove economic. Production in 2007 was 404,728 tonnes copper and 5,053 tonnes molybdenum. Mining is gradually moving lower and removing the ore between the barren country rock and the Braden Chimney. Access is through adits (horizontal tunnels) to shafts and other services cut in the Braden Chimney. Mining methods include panel caving, panel caving with pre-undercut, and block caving, which have been adapted to overcome the serious rockburst problem which stopped mining some years ago on level 6 and threatened the future of the mine. A new level, Level 8, is now in operation and another, lower, level is being studied which will give access to 1.5 billion tonnes of ore grading 0.96% copper and extend the life of the mine by many years. All ore is now treated in the lower Colón mill, the original Sewell mill being closed. Capacity is now 130,000 tonnes daily, split equally between SAG and conventional milling, followed by flotation, thickening and filtration. The recent increase in