Corrosion of archaeological artefact made of forged iron

One artefact of the archaeological cultural heritage from Roman period (IV century) that was found near Šabac in Serbia, was analysed. In corrosion products of the artefact (knife), dominant phases were goethite (α-FeOOH) and magnetite (Fe3O4). Presence of these types of corrosion products explains a good preservation of the base metal (iron) over the centuries and stability after excavation. Also, the less stable lepidocrocite (γ-FeOOH) and the phases that come from rocks and land surrounding environment (like SiO2) were identified in the corrosion products. Phases containing chloride ions (i.e. akaganéite) have not been detected in the corrosion products. This indirectly indicates that the amount chloride ions were rather low in underground exploitation conditions