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Published on: April 24, 2014
Mineralogical and geochemical provenance reference for turquoise from the Teghout Cu-Mo deposit in Armenia
Bahareh Shirdam1,2, Mingxing Yang3,4, Khachatur Meliksetian5
1Gemmological Institute, China University of Geosciences, Wuhan, 430074, China. shirdam@cug.edu.cn.
Abstract:
Turquoise from the Teghout Cu-Mo porphyry deposit (Lori Province, northern Armenia) forms veinlets and nodules in the supergene zone with quartz, Fe-Mn oxides, jarosite, barite and clay minerals, locally chalcanthite and gypsum. We provide the first integrated reference dataset for a substantial Caucasus turquoise source, providing the mineralogical and geochemical reference data needed to support future archaeological provenance research, collection authentication and heritage-science studies of exchange in the region. We emphasise that the Teghout occurrence was only discovered in 1974 during modern exploration and that no archaeological evidence currently links it to ancient turquoise supply; the reference framework presented here is intended to enable, not to substitute for, such future archaeological investigation. Gemmological testing, SEM imaging, EPMA, FTIR, Raman and LA-ICP-MS define a Cu-Al dominant turquoise near the ideal end-member. Raman spectra include variants with sulphate bands near 983 and 1007 cm-1. Trace elements show MREE-peaked, chondrite-normalised REE patterns with a broad Sm-Gd maximum, weak Eu anomalies, enrichment in Sr-Mo-Zn-Sc and very low V-Cr. Comparison with datasets from Meiduk (Iran) and Tongling (China), two porphyry-hosted turquoise localities, tests discrimination within a shared genetic framework; log-transformed Sr/V-Pb/Ba and Sr/U-Pb/U ratios distinguish the deposits statistically, although the Sr/U-Pb/U field is treated as supportive because Teghout and Meiduk show limited envelope overlap.
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