Jay Stephens and I have an NSF-funded project on the circulation of copper and copper alloys in southern Africa. As part of this Jay has run about 330 archaeological samples for lead isotopes (by MC-ICPMS) and chemistry (by solution ICPMS). There is a lot of bronze in samples dated after ca. 1250 AD, most of which is certainly of African manufacture - these are radiogenic, have very low lead (generally <150 ppm, often less than 10 ppm) and plot along the 207/204 vs 206/204 isochron for the Rooiberg tin mine (ore deposit of 2.05 Ga). Some of the bronze samples do however come from two 16th/17th century Portuguese trading "feiras" (Luanze and Dambarare) in northern Zimbabwe. Other samples are from the important site of Ingombe Ilede in the middle Zambezi Valley. This has no direct evidence of Portuguese presence, but has radiocarbon dates that calibrate between 1460 and 1640 AD - and so could be either pre-Portuguese or from the Portuguese era. The lead isotope ratios from all three sites are not radiogenic, and we are trying to decide whether these are African or Portuguese bronzes. (We don't think that they are Indian or Iranian, for reasons that we won't list here).