Ceramic abandonment. How to recognise post-depositional transformations

After they have been abandoned, ceramic materials may undergo substantial transformations, all of which may change their macroscopic aspect, mineralogy, chemical composition and microstructure. The intensity and pervasiveness of these transformations on both macro- and micro-scales depend to a great extent not only on their compositional and microstructural archaeological features, but also on the chemical-physical characteristics of the post-depositional environment in which they were hosted. This contribution describes the main post-depositional transformations observed in ancient ceramics in relation to secondary phases, precipitation, mineral dissolution, pristine mineral and amorphous phases, transformations into new mineral phases, and chemical leaching and enrichment. The mechanisms responsible for these transformations are described, together with the characteristics which allow us to identify them according to the most common analytical approaches, in order not to introduce misleading interpretations concerning study of the provenance and production technology of ancient ceramic materials