Characterization, diagnosis and conservation of copper ingots from the Arapal Wreck (Sancti Petri, Cadiz)

Abstract

An archaeometric and diagnostic study has been carried out on 78 copper ingots extracted in the surroundings of the islet of Sancti Petri. The epigraphic study of some of the inscriptions, with Roman numerals and capital letters, as well as the shape of the seals, allow us to circumscribe them to the Roman-Imperial period. The metallographic study reveals a structure typical of manufacture by casting, with holes in the matrix due to the degassing produced during the melting and subsequent cooling of the metal, as well as the dispersion of copper oxide inclusions and the absence of dendrites. A small stratigraphic sequence composed of cuprite and copper carbonates has been distinguished. The elemental analysis, reveals a 99.8 % Cu alloy, with Sb, Ag and As as major elements, showing coincidences
with ingots analyzed by other authors with possible origin in the Iberian Peninsula. The alterations products developed have depended on the conditions in which each ingot has remained in the environment, aerobic or anaerobic. Once the alterations were established, a series of works aimed at the conservation and restoration of the pieces were carried out.