Provenance and technology of relief and/or lustre glazed ceramics from Mértola (Portugal)

• Local production of relief, lustre and relief-lustre wares confirmed in Mértola by analysis of ceramics samples. • Distinct glaze technologies observed in samples from Mértola and Coimbra. • Coimbra samples linked to Middle Eastern lustre and glaze technology, indicating imports. • Lustre decorations were obtaine using coppr (Mértola) and silver plus copper (Mértola and Coimbra) This paper presents a study of a selection of lustre, relief, and lustre-relief glazed ceramics found at Mértola (12th–13th centuries), and Coimbra (11th century), Portugal (i.e. Garb al-Andalus during the Islamic period). The primary aim is to examine the possibility of a local production of lustre, relief, and lustre-relief wares at Mértola , and to compare the ceramic, glaze, and lustre technology employed with that applied in the production of lustre ceramics recovered at Coimbra , supposedly produced at Seville (Spain) during the 11th century. The analytical protocol included Optical Microscopy, X-ray Diffraction (XRD), X-ray Fluorescence (XRF), and Scanning Electron Microscopy coupled with Energy Dispersive Spectroscopy (SEM-EDS), in addition to High-Resolution Field Emission Gun Scanning Electron Microscopy (FEG-SEM). Considering the characteristics of the Mértola samples, during the 12th–13th centuries, different types of glazed ware, including lustre, relief, and lustre-relief, were locally produced, while others were imported. Conversely, Coimbra lustrewares evidenced significant technological differences, linking these samples to the Middle East tradition. To conclude, the results of this study evidenced, unexpectedly, that during the 11th century lustreware ceramics were imported into the al-Andalus , and not produced at Seville. The production started later, and Mértola ceramics from the 12th–13th centuries represent one ascertain example.