The key role of micro-Raman spectroscopy in the study of ancient pottery: the case of pre-classical Jordanian ceramics from the archaeological site of Khirbet al-Batrawy

Micro-Raman (μ-Raman) spectroscopy has been used, as a preliminary and non-destructive technique, in order to investigate the mineralogical composition and to define the maximum firing temperature and redox state of the firing atmosphere of ancient ceramic materials. The studied ceramics come from the archaeological site of Khirbet al-Batrawy (north-central Jordan), dating back to the Early Bronze Age (3000–2000 B.C.). The results show that the ceramic body is composed mainly by quartz and calcite, and minor amount of feldspars and hematite. In addition, apatite and zircon, important markers to identify the provenance of raw materials, have been detected. Furthermore, the occurrence of gypsum has been related to both rehydration of anhydrite and burial alteration processes. Micro-Raman spectroscopy was helpful to investigate the nature of the pigments of these ceramics: the red colour was obtained by hematite, the dark pigment by amorphous carbon. Mineral assemblage allowed estimating the maximum firing temperature of these pottery vessels between 850 and 950 °C. The comparison of the results of μ-Raman spectroscopy and of X-ray diffraction analysis suggests that μ-Raman spectroscopy could have a key role in the study of ceramic materials, especially the characterization of archaeological ceramic samples for which manipulation and/or consumption are not allowed.