Determination of the origin of blue sapphire using Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS)

Non-basalt-related and basalt-related sapphires can be distinguished on the basis of their trace element contents (sometimes called a chemical fingerprint), as determined with energy-dispersive X-ray fluorescence analysis. When using the oxide weight percent ratios of Cr2O3/Ga2O3 versus Fe(2)O3/TiO2 these trace elements show two discrete populations. However, for blue sapphires originating from non-basalt-related deposits in the Isalo area of Madagascar, from Ratnapura, Sri Lanka and from Mogok, Myanmar, a nearly complete overlap is observed whereas the overlap for basalt-related sapphires from Bo Phloi, Kanchanaburi, Thailand, New South Wales, Australia, and ChangLe, Shandong, China, is less significant. LA-ICP-MS was applied to obtain ppm and ppb-level data for 'ultra-trace elements' such as Zn, Sn, Ba, Ta and Pb. The results clearly show that they differ for blue sapphires from the sources investigated. The combination of trace element and 'ultra-trace element' contents offers the potential for providing useful criteria in identifying the geographical origins of sapphires and other gemstones.