Searching for Trace Elements in Lapis Lazuli from Myanmar for a Provenance Studies

This work is a continuation of a provenance study of lapis lazuli by means of different analytical techniques that our group started in 2008. The final aim is to find markers allowing to identify different provenances of this precious stone (mainly trace elements and luminescence properties). Up to now the work has been focused on 4 provenances: Afghanistan, Tajikistan, Siberia and Chile; using samples from these provenances we developed a protocol for their distinction that has been successfully applied both on carved artefacts and archaeological findings. We recently acquired samples from Myanmar, and started their characterization, to insert this provenance in the protocol. After some preliminary measurements using XRF (X-Ray Fluorescence) on large areas of the samples, we noticed that the presence of bromine seems to be a peculiarity of this provenance. For this reason we decided to go deeper and try to understand in which mineralogical phases it is present, taking advantage of the micro-PIXE capability to map the elemental distribution and to evaluate the amount of trace elements inside materials.