The principal aim of this project is to test the hypothesis for the origin of porphyry Cu deposits by comparing the petrology and geochemistry of ore-bearing and barren porphyries. If a difference is found it should be an invaluable empirical tool in the exploration for Porphyry Cu deposits. The most likely candidates are: (i) Differences in the oxidation state of ore-bearing and barren porphyries (ii) Difference in the PGE geochemistry of ore-bearing and barren porphyries resulting from differences in the timing or form (sulphide or sulphate) of S saturation. (iii) Textural differences relating to volatile saturation. (iv) The partitioning of Fe:Mg and D:H between coexisting biotite and hornblende as a means of identifying porphyries that become vapour saturated. The role of the student will be to study a classic ore-bearing and barren system in Chile. The suite of intrusive rocks associated with El Abra porphyry copper system will be used for the ore-bearing system, because we have the required samples at the ANU, and one of the well-studied Andes felsic systems as the barren system. The student will compile and compare existing data for both systems and collect existing data for both suites as required. The project will probably involve fieldwork in the Andes.