Characterisation of corrosion layers formed on ferrous archaeological artefacts buried in anoxic media

In the context of the in situ conservation and preservation of archaeological artefacts, the long term corrosion mechanisms of iron in anoxic soils are studied. To this purpose, a first step is the characterisation of the corrosion layers formed on archaeological artefacts provided from the archaeological site of Glinet (the sixteenth, Normandy, France). On all the corrosion systems formed on artefacts, the main phases constitutive of the corrosion layer are siderite (FeCO3), an iron carbonate containing hydroxide groups [probably chukanovite Fe2(OH)2CO3] and magnetite (Fe3O4). Furthermore, the arrangement of these phases reveals three corrosion distribution types with corresponding corrosion pattern diagrams.