Lead provenance of Late Roman Republican artefacts from Monte dos Castelinhos archaeological site (Portugal): Insights from elemental and isotopic characterization by Q-ICPMS

A set of lead artefacts were recovered at the Late Roman Republican archaeological site of Monte dos Castelinhos (Portugal), located in a prominent position on the right bank of the Tagus River, in the rear of its estuary. All artefacts, namely 16 shapeless fragment, seven glandes plumbeae and six possible metallurgical remains, were analysed using Q-ICPMS to determine minor and trace elemental compositions (Ag, As, Bi, Cu, Ni, Sb and Sn) and Pb isotope ratios. Statistical analyses of these data allow us to identify elements with similar behaviours and to differentiate raw materials used in the manufacture of the lead artefacts. Variation on the concentrations of Ag, Bi, Cu and Sb suggests galena as the most probable lead ore source, although some artefacts with a high Cu content may suggest the reduction of litharge obtained from argentiferous jarosites containing Cu. Pb isotope ratios point to raw materials with a probable Iberian provenance, namely from mines of the Sierra Morena and Ossa Morena Zone. Besides, there is evidence of the use of lead also resulting by the reduction of litharge, a by-product of the silver cupellation, in our case using argentiferous jarosites from the Iberian Pyrite Belt mixed with lead from other provenance.