Medieval and early modern ceramics from Azemmour (Morocco) - Textural, mineralogical and chemical analysis

A wide set of pottery was recovered by a Moroccan-Portuguese archaeological mission at the town of Azemmour (Morocco), between 2008 and 2011. The ceramic set can be divided into two distinct chronological groups: a medieval group (14th-15th centuries), mainly composed of refuse of a potter's production unit, and an early modern group (18th century), composed of potsherds recovered inside two cesspits from the palatine area (kasbah). The present work is an archaeometric study of 17 selected samples representative of the entire set, consisting of textural, chemical and mineralogical characterizations of ceramic pastes, in order to determine similarities and/or dissimilarities between the different fabric groups recognized in the archaeological pottery assemblages, and if the source of raw materials and production techniques remained the same or not in both chronological periods. Textural analysis of the pottery fabrics was undertaken using optical microscopy and petrographic analysis of thin sections. These were complemented by XRD (powder diffraction) analysis and Raman microscopy, while EDXRF analysis was also used for the chemical characterization of the ceramic pastes and glazes. With regard to texture all the ceramic groups are very similar. The results indicate that both medieval and early modern cooking vessels had coarse textured fabrics whereas non-cooking wares were predominantly fine textured. There are also many similarities between all groups regarding the mineralogical composition: quartz, calcite, feldspar, pyroxene and gehlenite are the predominant identified minerals, while chemical analysis also reveals that pottery vessels are made of similar calcareous pastes. Nevertheless, once again, cooking pots present higher concentrations of calcite and phyllosilicates and lower silica in relation to the other groups. It was also possible to estimate firing temperatures at above 800-950 degrees C for all ceramic groups. Thus, there is a strong possibility that the sources of raw materials and specific aspects of the production techniques used by Azemmour potters remained the same in both chronological periods.