Micro-Raman spectroscopy to investigate production techniques: A focus on fine ware potteries

The study of manufacture technologies and provenance of raw materials in archaeological potteries are two fundamental aspects in providing information about sociocultural aspects on past societies. The most acknowledged technique in this field is represented by minero-petrographic analysis, allowing to describe the compositional features of the artefacts and to link them to geological outcrops and technologic processes. In the case of fine-grained potteries, minero-petrographic analysis might sometime give back not clear results, requiring the use of high-resolved methods. In this framework, information about raw materials and firing techniques might be provided by the support of micro-Raman spectroscopy, able to supply information on mineral grains not detectable under a microscope and for which powders diffraction methods are not able to provide unique interpretations. In this work, particular attention was devoted to the phases formed during the ceramic body annealing, especially to newly formed feldspars, exhibiting a not natural occurring composition. Their correct identification, important for thermometric studies, is possible only with the use different techniques, due to the different investigated aspects (structure, composition and lattice dynamics). Fine-grained potteries from the famous site of Volterra, Tuscany (Italy) have been characterized as case study during a comparative evaluation of the results obtained by different techniques (micro-Raman analysis, optical microscopy [OM], X-ray diffraction [XRD] and scanning electron microscope energy dispersive spectrometry [SEM-EDS]) on the same mineral grains. The obtained results demonstrated how micro-Raman spectroscopy might improve interpretation of data collected with different methods in several aspects, from provenance to firing temperature estimation.