For the catalogue Altperuanische Kulturen I of the Museum of Ethnology at Berlin by D. Eisleb, a series of Peruvian weapons and tools of copper was analyzed. Two groups of metals were found: pure copper and copper with high amounts of arsenic. To find out which copper alloys were used at South America in the pre-Columbian period, a larger series of objects from the Museum of Ethnology was analyzed. It was found that bronzes with relatively high amounts of tin were also used. These results provide a reliable basis of a more detailed research on variations of the composition of these materials due to different periods and regions of origin. -- AATA