THE BLUE ROAD: PROVENANCE STUDY OF AZURITE SAMPLES FROM HISTORICAL LOCATIONS THROUGH THE ANALYSIS OF MINOR AND TRACE ELEMENTS

The pigments used by artists since ancient times play an important role in historical, artistic, and cultural investigations, as they allow the acquisition of useful information for the study of human and technological development. This research aims at differentiating the various sources of azurite exploited in antiquity, based on the study of minor and trace elements. Azurite is one of the most important blue pigments in art history, widely used during the Middle Age and Renaissance. However, very few studies investigated the provenance of the pigment, so today it is not yet possible to accurately identify the sources of azurite exploited in the past. This study is based on the analysis of several samples of azurite in the MUST collection (Museum of Earth Sciences, Sapienza University of Rome; Figure 1) coming from 8 different historical locations by electron microprobe (EMPA) and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS), with the aim of detecting chemical patterns that are characteristic of the different sources. Some of the investigated chemical elements have proved characteristic of specific localities, allowing to suggest valid criteria of discrimination. For example, Al, Si, and Mg were found indicative of the presence of clay minerals associated with azurite, while Zn, Pb, and Fe, were commonly documented as impurities within the mineral. Finally, a promising result also relates to the concentrations of some Rare Earth Elements (REE), as they might represent a marker for the discrimination of the investigated quarries.