Sourcing the ore from the Drierivier copper smelting site in central Namibia, using lead isotope fingerprinting

COPPER SMELTING RESIDUES FROM C. AD 1650 found at the Drierivier site near Rehoboth in central Namibia have 207Pb/206Pb isotope ratios that match a particular deposit at Swartmodder, but are markedly different from other known occurrences in the Rehoboth-Windhoek areas. For this reason, precise lead isotope determination is not necessary to source the ore, and raw peak height ratios obtained by inductively coupled plasma mass spectrometry are sufficient. This characteristic signature is present in all samples of malachite ore, slag, and copper prills collected on the site. Significantly, it is absent from a sample of local native copper, as well as from seven copper beads found elsewhere in central Namibia. This not only identifies the probable source of malachite ore but also provides a powerful tool for provenancing copper artefacts made at the Drierivier site, distinguishing them from those made elsewhere in the Namibian highlands.