J. T. Baldwin, H. D. Swain, and G. H. Clark
Geology and grade distribution of the Panguna porphyry copper deposit, Bougainville, Papua New Guinea (in Porphyry copper deposits of the southwestern Pacific islands and Australia)
Economic Geology and the Bulletin of the Society of Economic Geologists (August 1978), 73(5):690-702

Abstract:
Information from daily pit mapping of all working benches, since production commenced at Panguna in April 1972, has been used for improved mine production and metallurgical predictions, pit slope control, and the build-up of an orebody model for exploration.The present interpretation of the development of the orebody is as follows. A phase of copper iron sulfide mineralization was associated with the initial intrusion of the Kaverong Quartz Diorite/Biotite Diorite differentiate into the Panguna Andesite country rock. This mineralization was successively upgraded by a remobilization of copper sulfides with the intrusion of the Biotite Granodiorite and by an addition of higher grade copper associated with the Leucocratic Quartz Diorite. Breccias associated with the Biotite Granodiorite are significant sources of higher grade ore. Alteration is generally of weak to moderate intensity and essentially of the potassium and propylitic types. Quartz, sericite, and kaolin may locally become important.The evaluation diamond drill assays conservatively proved overall tonnage and grade, but the 122-m grid is too widely spaced for short-term mine planning. Production blast hole samples average higher Cu values than the evaluation diamond drill assays in low-grade mineralization.