Alteration processes of pottery in lagoon-like environments

Post-depositional processes in pottery can give rise to chemical and mineralogical alterations, the extent of which is closely related not only to the microstructure and composition of the potsherds, but also to the chemical–physical conditions of the burial environment. The present paper describes the characterization of post-depositional alterations and identification of processes involving pottery buried in lagoon-like environments. A set of various types of Roman transport amphorae and African Red Slip ware (ARS), collected from two archaeological sites characterized by a lagoon-like depositional environment and showing evident changes in the original colours, was analysed by a combination of microstructural, mineralogical and microchemical approaches. The formation of pyrite after hematite, jarosite after pyrite and microstructural substitution features are interpreted here in terms of the chemicophysical conditions of the burial environment and their evolution in time.