James D. Muhly: Sources of Tin and the Beginnings of Bronze Metallurgy: "Although there is still some uncertainty over exact details, it is now generally agreed that arsenical copper was produced by the direct smelting of an arsenical copper ore. The arsenic came down into the molten copper because it was present in the ore body, not because it had been added as a separate alloying element. It was thus impossible to control the amount of arsenic present in the copper. Published analyses of arsenical copper artifacts covering the years 4000-2000 B.C. show that arsenic content varied widely, supporting the theory that arsenical copper is a natural alloy...
#noted
