This research presents the first comprehensive archaeometric study of metallic artifacts recovered from the Herculaneum Archaeological Park, with a focus on the prestigious Herculaneum soldier's weapon set, discovered in the 1980s during the excavations along the ancient shoreline. The primary objective of this study was to characterize the original composition of the soldier's equipment and identify the corrosion products present in the set. Furthermore, in-situ non-destructive measurements and laboratory-based analyses were conducted to evaluate the conservation status of the set. Analytical results revealed extensive silver halidization on the decorative belt and sword, with chlorargyrite identified as the predominant corrosion product, alongside bromide-related phases indirectly inferred from elemental data. The iron components of the belt and the dagger exhibited iron corrosion, primarily consisting of magnetite and goethite. Notably, the investigation also identified a suite of sulfur-rich compounds within the dagger's wooden scabbard, including pyrite, ammoniojarosite, boussingaultite and mirabilite. These mineral phases are attributed to a common, now-obsolete, early 20th century conservation treatment based on the impregnation of submerged wooden artifacts with alum solutions which subsequently interacted with the corroding metallic core. The subsequent recrystallization of these salts results in severe structural decay of the wooden components, highlighting the urgent need for conservation treatments to stabilize the wooden part of the dagger and prevent further damage.
Huidobro et al. (2026) studied this question.