Gemmological and mineralogical investigations and genesis of the massive purple jade from the Harmancik-Bursa region

In the Harmancık-Bursa region of the western Anatolia (Turkey), an extensive contact metamorphic aureole at the border between the Late Mesozoic coherent metaclastic rocks of blueschist facies and the Early Cenozoic intrusive granodiorite stock, hosts a gem material with a mineral assemblage consisting mainly of jadeite, quartz, orthoclase, epidote, chloritoid, and phlogopite minerals. In addition, the chemical analyses show that the mass of the metamorphic aureole has a silica rich calc-alkaline chemical content.This pale purple-colored material is only found in one narrow provenance in Turkey. Therefore, it is specially called ?Turkish (and/or Anatolian) purple jade? on the worldwide gem market. Even though the mineral jadeite is the principal constituent, 40% by volume, the material cannot be considered pure jadeite.Specific gravity value of the jade has unusual. The measured average specific gravity of 3.04 is significantly lower than the normal range for characterized jadeites of 3.24 to 3.43.Dispersive confocal micro-Raman spectroscopy (DCµRS), as well as the other well-known analytical methods was used to characterize and identify in detail the Turkish purple jade samples. Accordingly, the strong micro-Raman bands that peaked at 1038, 984, 697, 571, 521, 464, 430, 372, 326, 307, 264, and 201 cm-1 are characteristics of the Turkish purple jade.Turkish purple jade samples show numerous broad and intensive luminescence bands. Different luminescence centres produced by cathodoluminescence (CL), radioluminescence (RL), and photoluminescence (PL), and excited by using irradiation, are due to the overall signals, even though thermoluminescence (TL) sensitivity varies depending on the treatment of the jade samples.Finally, these parameters provide positive identification with the provenance (geographic origin) of the original Turkish purple jade. It can be seen that the obtained dispersive confocal micro-Raman bands, specific gravity values, luminescence spectra, and trace element contents provide a unique fingerprint for this kind of jadeite-jade gem materials.