Centro de Ciências e Tecnologias Nucleares

The present study aims to contribute to the identification of mineral deposits used as raw source in the production of glandes plumbeae, accidentally recovered in Alto dos Cacos (Almeirim) and attributed to the Roman Period, and some bronze alloys, recovered from Fraga dos Corvos (Macedo de Cavaleiros) Bronze Age archaeological site. Therefore, methodologies to determine the lead isotope ratios in small samples taken from the archaeological metallic artefacts by quadrupole inductively coupled plasma mass spectrometry (Q-ICPMS) have been developed.
The collection was composed by 24 glandes plumbeae, obtained by different manufacture processes including casting. The lead isotope ratios obtained values by sample dissolution in HNO3 20% did not allow to establish groups having different isotopic compositions, which suggests a probable local production.
Bronze alloys from Fraga dos Corvos were composed by 4 archaeological artefacts and 2 fragments of metallurgical remains. In this case, after acid dissolution with HNO3 20%, the anodic electrochemical separation of Pb from the bronze matrix was performed. The obtained isotope ratio distribution patterns evidenced the existence of two distinct groups, which may indicate exogeneous influences and/or the use of ores with different origin
In the comparative study with Iberian mineralogical deposits, significant correspondences among the Pb isotopic patterns of bronze artefacts and those of mineral deposits from Sierra Morena and Basque-Cantabria basin were observed. Lead artefacts seem to be better associated to deposits from Andalusia-Murcia and Basque-Cantabria, but also from the south of France (Cévennes and Mont-Lozére Massif) and Sardinia.

During Roman times, lead was widely used, namely for military weapons, like leaden sling projectiles (glandes plumbeae). This work presents a preliminary study of elemental and Pb isotope analysis of 24 glandes plumbeae with different typologies accidentally discovered at Alto dos Cacos (Almeirim) and possibly related to the Roman army from Hispania Ulterior. The artefacts were analyzed by energy dispersive X‑ray fluorescence (EDXRF) and quadrupole based inductively coupled plasma mass spectrometry (ICP‑QMS). The elemental analysis indicates some trace elements in lead matrix. The lead isotope composition analyses distinguish two groups, regardless of typologies.

A set of bronzes recovered from Fraga dos Corvos (Macedo de Cavaleiros) archaeological site, located in Northern Portugal, was analyzed to investigate their lead isotope ratios. The studied metallic artefacts have diverse typologies and include two bar fragments, four fibulae, a pendant and fragments of a possible cauldron. Besides these, two metallurgical remains (nodule and droplet) were also analyzed. Elemental analysis by μ-EDXRF showed that bronzes have a Sn content varying between 5.1 and 13.9% and a Pb content from 1.4 to 6.1%, which allowed to select a suitable methodology for lead separation, prior to isotope ratio determinations. In these alloys the Pb isotope determinations (204Pb, 206Pb, 207Pb and 208Pb) are influenced by matrix effects that decrease the sensitivity and the reproducibility of the measurements. Analytical procedure consisted in electrochemical Pb separation by anodic oxidation. The determination of Pb isotope ratios was made by ICP-MS with a quadrupole ma...

During Roman times, lead was widely used, namely for military weapons, like leaden sling projectiles (glandes plumbeae). This work presents a preliminary study of elemental and Pb isotope analysis of 24 glandes plumbeae with different typologies accidentally discovered at Alto dos Cacos (Almeirim) and possibly related to the Roman army from Hispania Ulterior. The artefacts were analyzed by energy dispersive X ­ray fluorescence (EDXRF) and quadrupole based inductively coupled plasma mass spectrometry (ICP ­QMS). The elemental analysis indicates some trace elements in the lead matrix. The lead isotope composition analyses distinguish two groups, regardless of typologies.