Micro-PIXE and micro-IBIL characterization of lapis lazuli samples from Myanmar mines and implications for provenance study

Abstract

The provenance of raw lapis lazuli used since the Neolithic Age for the realization of carved artefacts can be pivoting for the reconstruction of ancient trade routes. The role of main provider of this material in ancient times is generally attributed to the Badakhshan quarries (Afghanistan), although other deposits could have been exploited as well since antiquity. The systematic multi-technique analysis of lapis lazuli rocks coming from four known source areas (located in present-day Afghanistan, Tajikistan, Siberia and Chile) has led in the last years to the compilation of a protocol for provenance determination. The protocol is based on differences in the physical–chemical properties measured with non-invasive techniques (Ion Beam Analysis (IBA)), making it suitable also for precious ancient artefacts. In this work, 10 new reference samples from the Mogok quarry (Myanmar), previously subjected to a complete petrographic and mineralogical characterization, have been analysed employing $$\mu$$ μ -PIXE (Proton Induced X-ray Emission) and $$\mu$$ μ -IBIL (Ion Beam Induced Luminescence) techniques. The subdivision of Myanmar samples into three groups, previously suggested, is corroborated by diopside trace elements concentrations. The results also allow to include Myanmar as a new provenance in the analytical protocol, indicating that provenance markers such as presence/absence of wollastonite, altered pyrites and Sr content are still valid to discriminate also the Myanmar lapis lazuli from Chilean or Siberian ones. New weaker markers (Zn content in diopside, Se and Cu contents in pyrite) are proposed for the discrimination of Myanmar from Afghan or Tajik provenances; however, from the analysis it arose the need of investigating new mineral phases with IBA to find strong markers for a definitive discrimination with samples from Southwest Asia.

Minero‐chemical and provenance analysis of Achaemenian lapis lazuli cylinders from Persepolis

“…Recently, analytical protocols have been reported for the provenance study of ancient carved lapis lazuli objects (Angelici et al, 2015; Lo Giudice et al, 2017; Re et al, 2013). In the most recent protocols, the following markers are suggested (Guidorzi et al, 2023; Lo Giudice et al, 2017): Presence/absence of wollastonite: its absence shows that the lapis lazuli rocks are from Tajikistan, Afghanistan or Siberia. Presence/absence of altered pyrite and Sr in diopside: their absence shows that the lapis lazuli rocks are from Tajikistan and Afghanistan. Ni/Cu ratio in the pyrite: a higher Ni/Cu ratio shows that the rock is from Afghanistan (Badakhshan). The protocol was based on the study and analysis of four main provenances: Ovalle (Chile), Liadjura‐Dara or Lojvar Dara (Tajikistan), Badakhshan (Afghanistan) and Lake Baikal (Siberia). Though this classification has been performed via microanalytical studies by micro‐proton‐induced X‐ray emission (μ‐PIXE) and ionoluminescence techniques, they may help us to interpret the obtained data from Persepolitan objects.…”

“…It shows that the Achaemenian lapis lazuli objects are made of the Central Asian resources. It is worth noting that Tajikistan (Liadjura‐Dara) is also another recently discovered source of lapis lazuli in Central Asia, but the analytical results show that lapis lazuli from Tajikistan has a different chemical fingerprint than the Afghan rocks (Guidorzi et al, 2023). On the other hand, the fingerprint of the Achaemenian samples correlates well with the Afghan sources in Badakhshan.…”

“…most recent protocols, the following markers are suggested (Guidorzi et al, 2023;Lo Giudice et al, 2017):…”

“…(Tosi & Piperno, 1973) and in the Eastern Mediterranean region, indicating the existence of an ancient long-distance trade route (Brøns et al, 2020). Nevertheless, numerous lapis lazuli sources in the world may have been used for other ancient civilizations, ranging from the Far East to Europe (Guidorzi et al, 2023;Lo Giudice et al, 2017). Achaemenian artists may have had easy access to the Afghan resources due to the extension of the eastern Persian Empire's borders to eastern Afghanistan and western China (Wiesehöfer, 2009).…”