An Archaeometric Study of Chinese Porcelain Sherds Found at the Santana Convent in Lisbon—Part 2: A Comparison with Coeval Chinese Samples of Well-Known Provenance

This study presents an archaeometric characterization of fifteen blue-and-white Chinese porcelain sherds (17th–19th centuries) from the Jingdezhen, Anxi, and Dehua kiln systems, compared with fragments recovered from the Santana Convent (Lisbon), particularly eighteenth-century materials. A combination of non-invasive, minimally invasive and micro-destructive techniques, including Ground-State Diffuse Reflectance Spectroscopy (GSDR), X-ray Photoelectron Spectroscopy (XPS), micro-Raman spectroscopy, X-ray Fluorescence (XRF), X-ray diffraction (XRD), and stereomicroscopy, was employed to investigate cobalt pigments, glaze composition, firing conditions, and provenance indicators. The results reveal systematic differences between dark- and light-blue glazes, reflecting distinct pigment-processing technologies or simple concentration effects inducing different cobalt coordination environments and/or oxidation states. Raman spectroscopy confirms that cobalt occurs mainly as Co2+ ions dissolved in the amorphous silicate glaze matrix. No Raman-detectable crystalline cobalt silicate or cobalt aluminate phases were identified. XRF and XPS analyses show elevated Mn/Co and Fe/Co ratios combined with extremely low arsenic contents, suggesting the predominant use of domestic Chinese cobalt sources. XRD analyses identified quartz, mullite, and minor anorthite, consistent with traditional high-fired hard-paste porcelain technology. Dark-blue radiating star-shaped colored radiating features, particularlyfrequent in Dehua porcelains, were also identified in selected Santana Convent samples, suggesting their attribution to Dehua kiln production and demonstrating the value of glaze defects as complementary provenance markers.