Geology and MineralizationSanta Ana is a volcanic-hosted, epithermal system hosting large volumes of exposed, primarily oxide silver mineralization. Mineralization is contained within numerous structural feeders and in widespread crackle breccias (with disseminated carbonate and barite) that crosscut and replace bedding in the volcanic sequence. Tertiary andesite flows and pyroclastics have been intruded by sub-volcanic quartz feldspar porphyries and hydrothermal breccias. Dacite domes and breccias play an important role in ore deposition at the San Cristobal silver deposit being developed by Apex Silver Mines in neighboring Bolivia.Bulk-tonnage silver deposits such as Santa Ana are uncommon; however,there are several examples of heap-leachable ore bodies proving to be very successful operations due to the simplicity of operations and low operating and capital costs. One of the best examples is Couer-Rochester, Nevada which has recovered silver in cyanide leaching successfully for several decades. | |