Analysis of early copper-base artifacts invariably reveals traces of iron. Iron enters the copper during the smelting process, and the level of iron in the metalwork is an indication of the smelting technology. In areas such as Western Europe where prehistoric slag heaps are absent even in the proximity of undoubted ancient mines, the iron content is low reinforcing the link between smelting technology and iron content. Very occasionally the iron content was deliberately encouraged, and alloys containing between 30% and 50% of iron in copper were made, mainly for use in currency. These alloys are without modern parallel, and their metallography and method of production are considered in some detail here. -- AATA