Portuguese 16th to Early 18th Century tin Glazed Ceramics Found at the Tagus Estuary Saltpans

UID/NAN/50024/2019 M-ERA-MNT/0002/2015 UIDB/04209/2020 UIDP/04209/2020 Salt was extracted from saltpans, in the South shore of Tagus River by evaporation of the salted sea water which penetrates into the estuary. The walls and the bottom of those saltpans were made of local clays to retain the sea water, and ceramic sherds have been used to endure those walls and also to allow people to walk on the saltpans’ walls. Those sherds constitute an example of the ceramics production in Lisbon workshops, starting in the mid-16th century and reaching high levels of quality in the 17th and 18th century. A detailed archaeometric study of 14 selected sherds dated from the 16th to the early 18th century has been made and the conjugation of the information provided by the micro-Raman, XRD and XRF experiments for those sherds and clays collected locally, allowed us the characterisation of the Lisbon ceramics in that period. Three main groups could be identified in the ceramic bodies; all made with locally collected clays of Miocene origin. In the first group, the potters used raw materials from the clay sources located at Santa Catarina area in Lisbon, most probably mixed with Lapa clays, which were fired at a high temperatures, ranging from 850ºC to 950ºC. Gehlenite and quartz are the dominant minerals of these ceramic bodies. In the second and third groups of Lisbon ceramic bodies, made with Prazeres clays, diopside was also detected but with variable amounts of gehlenite. Clay formations mineralogy mainly include kaolinite, muscovite/illite, quartz, calcite, and feldspars (albite and microcline). publishersversion published