1981 Volume 31 Issue 170 Pages 421-428
The Huanzala mine is a copper, lead and zinc mine in Peruuian Andes. The orebodies are bedded or lenticular in shape and occur within several limited stratigraphic horizons of a limestone formation of Cretaceous age. Some intrusive sheets of quartz porphyry (7.5-9.2 m.y.) occur in the vicinity of the ore horizons. On the basis of their mode of occurrence and mineral assemblage, the ores are divided into the following three types, i. e. pyritic ore, skarn ore and "shiroji" ore (argillized ore). They are considered to have been formed by pyritization, skarnization and subsequent hydrothermal replacement processes probably related to the intrusive activities of the quartz porphyry. The mineralization sequence is as follows: pyritization→skarnization with Fe-rich sphalerite mineralization→.galena mineralization followed by chalcopyrite mineralization→"shiroji" alteration with Fe-poor sphalerite mineralization→bornite and, chalcocite mineralization→tennantite mineralization.
It is stressed in this paper that the initial pyritization or the pre-existing pyrite deposit must have played a role of prime importance in a variety of subsequent economic mineralizations. The Pb-Zn mineralization took place within the pyrite deposit to have formed the pyritic economic ores. The pyrite deposit, which has previously been regarded as a barren core of the zonal arrangement of the Huanzala mineralization, should be considered to be the most important target for exploration in this mining area. The quartz porphyry is also important for exploration. It occurs always close to the orebodies, suggesting its intimate genetic relation to the mineralization. The southeastern extension of the Huanzala mining area, which is interposed by the quartz porphyry mass, is suggested to be quite promising for future exploration. On the basis of these exploration strategies, some encouraging results are now being obtained.
