The Antamina intrusion (9.8 Ma2) is a multiple phase, quartz monzonite porphyry and has the Antamina Cu-Zn skarn developed around it. There is a nearby intrusion of similar composition with narrow, weakly mineralized skarn 1.5 kilometers northwest at Condorcocha.
Antamina is a polymetallic (copper, zinc and molybdenum predominate) skarn deposit resulting from complex multiple intrusive events. Copper mineralization occurs mainly as chalcopyrite except for some areas of bornite, representing approximately 5% of the deposit. Zinc mineralization generally occurs as sphalerite. Other significant sulphide minerals include molybdenite and pyrite, while trace amounts of numerous silver and bismuth bearing minerals and local areas of galena (lead sulphide) are also found within the deposit.
Antamina deposit is unusual in its persistent mineralization and predictable zonation, and has a SW-NE strike length of more than 2,500 metres and a width of up to 1,000 metres.
The Antamina and Usu Pallares deposits comprise a very large copper skarn with zinc, silver, molybdenum, lead, bismuth and arsenic formed by the intrusion of quartz monzonite body into limestones. Characteristics of the skarn zone depend upon the nature of both the intruded rock and the emanations from the intrusive body. Two types of alteration are recognized; recrystallization, or rearrangement of the constituents already in the rocks, and addition of chemical elements. Most skarn deposi ........
