At the La Coipa mine, Chile.   Left and top-centre: The alteration zones of the mineralised system are obvious within and adjacent to the Breche Norte pit, from hypogene mineralisation in volcanic and sedimentary rocks, through advanced argillic, to steam-heated vuggy silica, to upper steam heated and then overprinted supergene oxides.   Right: The steam heated overprint of vuggy silica alteration on a 10 m face between benches in the upper levels of the deposit;   Lower centre: Carlos Peralta, exploration geologist for Compañia Minera Mantos de Oro points out features of the deposit to Gustavo Zulliger of Rio Tinto, Argentina.

  The day had begun with yet another early start and a two and a half hour drive in the charter bus into the mountains from Copiapo to the La Coipa mine complex. The group was given a series of comprehensive presentations on the setting, geology and mineralisation at La Coipa, before proceeding to the Breche Norte pit to inspect the geology, alteration and mineralisation at three different sections of the pit. This was followed by core inspection during the lunch time blast, before inspecting the rocks in the Laredo-Farellon pit. The group departed in the mid to late afternoon to be back in Copiapo before dark.

Photographs by Mike Porter