Lead isotope evidence of lead supply in ancient Ilduro (second-first centuries B.C.E.)

In this article, we study the provenance of the lead contained in 22 objects found in the excavations conducted since 1998 on the ancient site of Ilduro (Cabrera de Mar, Barcelona), located in the north-east of the Iberian Peninsula. A selection of 12 bronze coins and 10 lead objects recovered from households, workshops, and the public baths of the town were examined by means of Thermal Ionization Mass Spectrometry (TIMS) to document the lead supply and trade networks between, on the one hand, the indigenous peoples known in the classical sources as the Laeetani and, on the other, the Roman provincial administration and the societates that controlled the natural resources, their exploitation, and distribution during the Late Republic (second-first centuries B.C.E.). There is no doubt about Rome’s dependence on the considerable output of the lead and silver from Hispanic mines during this period; however, very little is known on how these mines supplied and affected the lives of the local communities in Hispania over the course of time. This study helps to cover this gap in the existing literature. The results show how all the coins have lead isotope ratios with homogeneous values compatible with an origin in the Spanish mining district of Cartagena-Mazarrón. The isotopic composition of the 10 lead objects is not homogeneous, and it is possible to identify three distinct clusters. The samples in cluster 3, which include all the artifacts from the bath complex, can also be attributed to the mining districts of Cartagena-Mazarrón, demonstrating that a single mining district supplied the lead required for these two specific initiatives: minting and the construction of the baths. However, the provenance of the lead in the remaining samples (workshops and households) remains unresolved and in some cases might be a consequence of remelting or the direct mixing of leads with different origins. The data from Ilduro points towards the existence of different lead supply patterns in the settlement: directly from the mining exploitations for the public enterprises in contrast to the recycling and mixing practices detected in households and workshops.