Microanalyses were performed on principal ore minerals-pyrite and chalcopyrite-from the porphyry copper deposits of the Mamut Mine, East Malaysia. The result reveals that Ag and Mn are concentrated in chalcopyrite; and Mo, Ni, Co, Pb and Bi in pyrite. In general, the minor element variability in chalcopyrite is smaller than that in pyrite. Minor element abundances in pyrite and chalcopyrite vary with host rock types. The Ni composition of the sulfide minerals is likely due to mixing of Ni from the host rocks with Ni derived from the ore fluid.
Comparing the analytical data from the Mamut deposit with those from the Bingham deposit and the Santa Rita deposit, it can be pointed out that chalcopyrites in the former deposit are generally richer in Ag and poorer in Sn, Mo, Bi and As than in the latter deposits.