Chapter 7 - Applied mineralogy: Porphyry copper deposits

Abstract

Applied mineralogy is an indispensable tool in exploration of porphyry copper deposits and in mineral processing of porphyry copper ores. It is used to a greater or lesser degree throughout the entire period of exploitation of most deposits. An important aspect of exploration of porphyry copper deposits is characterizing the host rocks and mineralized zones, and classifying the deposits. The characterization involves identifying the minerals, determining mineral quantities, and determining the textural relationships among the minerals, mineralized veins, and the wall-rock. The main minerals are normally identified by examining hand specimens or drill cores, but the identities of some minerals need to be determined or confirmed by other techniques; usually by microscopical studies of thin or polished-thin sections, supplemented by microprobe (MP) analyses. Textural relations of minerals are determined by optical microscopy. No field geologist looking at thin sections part time can acquire the breadth of experience of a person dedicated to petrography and so the samples should be examined by a competent petrographer. The petrographer needs feedback from the field geologist to provide usable information related to exploration rather than just rock descriptions.