The silver treasure of Marengo: silver provenancing and insights into late antiquity Roman and Gallo-Roman hoards

Lead isotopic ratios were measured on silver fragments extracted from several important objects of the hoard of Marengo. The hoard, known as the Btreasure of Marengo^, is one of the most important silver assemblages of late antiquity. It is dated to the second half of the 2nd century AD-first half of the 3rd century AD. The interpretation of the resulting isotopic data based on extended reference isotopic databases of lead/silver ores indicates that most of the analysed objects from Marengo form a rather homogeneus stock of silver metal having a signature affine to the mines of French Massif Central. One of the objects, a large belt with figures of divinity and heroes, was made of Iberian silver, and the Pb-Ag-Cu alloy present in the filling of the arm of a female statuette is rich in Sardinian lead. The results are discussed in terms of the known circulation of silver metal in the Roman Empire in the 1st and 2nd century AD. The lead isotope data are compared with available data on coeval Roman silver hoards (Notre Dame d’Allençon, Berthouville, Graincourt-lès-Havrincourt, Boscoreale), circulating silver denarii, and Roman lead ingots rescued from shipwrecks in the Western Mediterranean sea. The role of the Iberian and French mines in the silver production from the 1st to the first half of the 3rd century AD is discussed.