Islamic and post Islamic ceramics from the town of Santarém (Portugal): The continuity of ceramic technology in a transforming society

The study presents and discuss the results obtained by the archaeometrical investigation carried out on Islamic and post Islamic ceramic recovered from the town of Santarém, located on the right bank of the river Tagus, at 80 km from Lisbon, Portugal. The objects of this study come from several archaeological excavations covering a chronological timeframe between the VIII and the XV–XVI centuries, before and after the conquest of the town by Christian in the middle of the XII century. The collection includes unpainted, white painted, red painted and glazed ceramics of Islamic and Post Islamic chronology. Amongst the glazed ceramics, 2 samples of “corda seca” polychromatic ceramics were recovered in two different workshops, in one case associated to kiln tools like stilts and kiln bars. The main goal of this study was to assess the continuity in raw material exploitation, the production technology, to assess the production of “corda seca” glazed ceramic and to understand how the Portuguese Reconquista affected ceramic technology. The mineralogy and petrography of the samples were determined by optical microscopy (OM), powder and micro X-ray diffraction (PXRD and μXRD), μRaman spectroscopy and attenuated total reflection-Fourier transform infrared spectroscopy (ATR FT-IR). Bulk chemical analysis was obtained by X-ray fluorescence spectrometry (XRF) and inductively coupled plasma mass spectrometry (ICP-MS). Microanalysis of the ceramic paste and of the decorative layers (glazed or painted) was performed utilizing a scanning electron microscope coupled to an energy dispersive X-ray detector (SEM-EDS). Results indicated that the samples were locally produced, suggesting, in particular a local production of poly-chromatic glazed ceramic during Islamic period in two different workshops. Ceramic technology did not change with the Portuguese Reconquista, confirming that a modification in the political power did not correspond to a change in ceramic technology.