O chumbo dos sistemas hidráulicos romanos no Ocidente Peninsular: proveniência e processos metalúrgicos

Gomes, Susana Sousa; Araújo, Maria de Fátima; Soares, António; Correia, Virgílio Hipólito

Key information

Authors:

Gomes, Susana Sousa (Susana Alves de Sousa e Silva Gomes); Araújo, Maria de Fátima (Maria de Fátima Duarte de Araújo); Soares, António (António Manuel Monge Soares); Correia, Virgílio Hipólito

Published in

2020

Abstract

Lead metal was largely applied in the manufacture of water pipes used in complex hydraulic systems to supply and distribute water to public baths and private houses during Roman times. Therefore, research on lead sources and metallurgical techniques may provide significant information on trade routes during those times. A widely used method which combines Pb isotopes ratios with minor and trace elemental contents and archaeological data has been providing significant information on the raw material provenance. In the present study 77 samples were analysed, composed by 44 fragments of lead water pipes from Conimbriga, 21 from Augusta Emerita, six from Mirobriga, three from Arucci/Turobriga, one from Fuente Seca and two from Cortalago, the last located in the vicinity of the Iberian Pyrite Belt in Baetica province. Analyses were performed by mass spectrometry (ICP-MS) to determine Pb isotopic ratios as well as some minor and trace elemental (Ni, Cu, As, Ag, Sn, Sb and Bi) contents. Sn concentrations suggest that most samples were manufactured with recycled lead containing tin solder. Besides, the Ag contents, sometimes combined with Cu and Ni concentrations, indicate that the lead was obtained by litharge reduction or smelting of non-argentiferous galena. Comparison with published data of Iberian Peninsula mineralogical deposits, displays significant correspondence between the Pb isotopic signature of several lead pipes and lead metal from Ossa Morena Zone and Sierra Morena, or a mixture of these with lead from the Iberian Pyrite Belt.