gems, Egypt, Iran, Non-invasive analysis, Scanning XRF, Sinai, Turquoise, X-ray fluorescence spectrometry

More than 1400 turquoise stones associated with 98 archaeological artifacts from Egypt, the Near East, and Central Asia were analyzed using non-invasive point and scanning XRF. Geological specimens of turquoise from mines in the Sinai and Iran were also included in this study. The relative intensities of characteristic X-rays of Fe, Cu, Zn, and As were used to categorize the stones, which are discussed here in terms of their geographical contexts and assigned dates. The results indicate strong correlations between turquoise composition and archaeological attribution. Although these relationships likely reflect differences in turquoise sources that changed over the course of several millennia, it is not possible to associate the chemical signatures with specific mines solely using non-invasive XRF data.