On the importance of using scandium to normalize geochemical data preceding multivariate analyses applied to archaeometric pottery studies

This work enhances the importance on determining regional geochemical background by normalizing chemical data of archaeological ceramics, using one element as grain-size and mineralogical proxy, prior to any further statistical approach. It is well established that more relevant information can be derived from the concentration of any element when it is compared with some reference element. The main question is which element should be chosen to normalize concentration. A discussion on this issue is presented here.A case study is presented, which includes the geochemical tracing of Roman kilns productions, differentiating between and within two sedimentary basins pottery assembly, belonging to several Roman ceramic production centres identified in the Tagus and Sado basins of Portugal. Due to the homogeneity of the used raw materials (estuarine sediments), the distinction and establishment of signatures for each production center become difficult.A multivariate statistical approach after normalization of the chemical contents to a conservative element (Sc) is presented, well differentiating the three production centers and allowing the establishment of provenance for amphorae.