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I agee with Pedro that the occurrence of Cu/As, Cu/Sb and other odd alloys is more likely the result of particular co-occurences of minerals than of intentional additions. I have a current field project in the Rooiberg valley of South Africa, where some very odd copper alloys have been found over the last hundred years - Cu/As up to 23% As, Cu/Ni/As, and so on. Over the last couple of field seasons we have tried to visit all known outcrops of metallic minerals in the valley and sample from the dumps. We've recovered a wide range of green minerals, including annabergite (hydrated nickel arsenate) and olivenite (hydrated copper arsenate). My impression is that prehistoric metalworkers in this area were just collecting and smelting anything green (but not blue - even though azurite is common on the dumps, I've never seen it on a smelting site). The resulting alloys were therefore very variable, and the unusable products (very high As) were simply discarded unworked for the archaeologist to find. -- David Killick Associate Professor Department of Anthropology University of Arizona Tucson, AZ 85721 office: (520)621-8685 laboratory: (520)621-7986