A whiter shade of vase. Discovering the white colors of an ancient Apulian krater through XRPD and Raman spectroscopy

Raman spectroscopy and X-Ray Powder Diffraction were applied in order to characterize the materials used for the manufacturing of an ancient, decorated vase of Apulian manufacturing in 4th century B.C. In this case study, three small fragments from one vase were sampled from pictorial areas in black and white. X-Ray Diffraction on a powdered sample was applied to characterize the composition of ceramic: the analysis allowed the identification of quartz, plagioclase and diopside and consequent hypotheses about the production process. The pictorial decorations in black and white were analysed through Raman spectroscopy. While the pigment constituting the dark areas was identified as maghemite γ-Fe2O3, an iron oxide with spinel structure, which suggests a maghemization oxidative process, in the white decoration it was possible to individuate the presence of both anatase -an allotropic phase of titanium oxide- and α-alumina. The application of alumina as pigment results peculiar and it represents a new knowledge advancement, which is worth of further studies. The combination of anatase and alumina suggested hypotheses about the origin of the starting materials for the white decorations, with reference to the manufacturing period and area. This set of data resulted in new information about the Apulian vase production, enriching the knowledge about a less popular pottery typology and opening new perspectives about commercial and cultural exchanges.