An Archaeometric Study of Twelve Porcelain Chinese Sherds Found at the Santana Convent in Lisbon – – 16th to 18th Centuries

Twelve sherds of blue-and-white Chinese porcelains recovered from archaeological excavations in the Santana Convent, in Lisbon, were studied using several non-invasive spectroscopies, namely micro-Raman, X-Ray Fluorescence (XRF), Ground State Diffuse Reflectance (GSDR) and stereomicroscopy. The use of the X-ray diffraction technique (XRD), allowed us to complete the mineralogical characterization of the ceramic bodies and glazes of the porcelains. The sample selection ranges from the 16th to the 18th centuries. The micro-Raman spectra clearly showed two types of glazes, alkaline glaze and calcium-based glaze. The GSDR absorption spectra of the blue glazes points to the use of different cobalt pigments but a strong dependence on the glaze type does not seem to exist. The kilns where the porcelains were produced also play an important role. Both the GSDR absorption and the micro-Raman spectroscopies allow us to differentiate the Iranian blue pigment from the Chinese pigment. A direct and simple correlation between the use of Iranian blue pigment, mixtures of Iranian and Chinese pigments or simply Chinese pigments and the stylistic dating of each sample was established. Furthermore, several important spectroscopic characterizations could be achieved in this study.