Ricerc@Sapienza

This project is intended as an in-depth study on the origin of the precious red pigment cinnabar by Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS). The importance of this pigment is partly due to its low availability. When the mineral was used in the Roman Age, the district of Almadén, Spain, was probably the most exploited region. However, it is still not well defined if further ores were chosen for supply. It has been recently proved that a few localities show remarkable structural or chemical variations that can be associated to a specific provenance. In the present project, cinnabar samples with known provenance (Spain, Slovenia, Italy, Russia, China and minor European deposits) and already collected from Italian Mineralogical and Earth Science Museums will be analysed by LA-ICP-MS. The project aims at integrating data previously collected by XRD and ICP-MS. The latter was used as a previous screening to define the list of chemical elements to be investigated and then preliminary attest chemical variability. It showed that Chinese samples have already shown to be characterized by selenium. Other elements were found has indicative of a specific exploitation site, namely Li, Si, Fe, Co, Cu, As, Se, Rb, Sr, Y, Zr, Mo, Cd, Sb, Te, La, Ce, Pr, Nd, Eu, Sm, Gd, W, Tl, Pb, Bi, Th and U. LA-ICP-MS is hereby proposed to avoid the difficult sample preparation required for cinnabar by ICP-MS. The aim is to systematically measure trace elements concentration and highlight chemical markers to be linked with provenance. Finally, data treatment by principal component analysis (PCA) is also planned. LA-ICP-MS is intended as a promising in-depth step to extend knowledge on cinnabar trades and provenance in ancient times using a single, micro-destructive, fast and innovative technique. Defining provenance criteria may be also fundamental for Conservations Scientists to detect forgeries.