A crude copper ingot from Ica, Peru, was found by quantitative analysis to contain 0.2% of sulfur. This amount of sulfur indicates that the ingot must have been produced by the smelting of one of the sulfide copper ores found in this region. Most analyses of preconquest Peruvian copper objects have been made by spectroscopic methods which do not detect sulfur. It has been assumed, up to this time, that if the Peruvians could smelt copper at all, the process was confined to such simple ores as oxides and carbonates. Many of the objects previously examined should be reanalyzed for sulfur. -- AATA