Spectroscopy and Spectral Analysis, Volume. 45, Issue 9, 2467(2025)
Spectroscopic Characterization of Turquoise From Nanhuatang, Shiyan, Hubei
The EYS(E-Hu-Shaan) turquoise mining area is a significant turquoise-producing region in China, with the Nanhuatang turquoise deposit located in the Yunyang District of Shiyan City, Hubei Province. This study systematically investigates Nanhuatang turquoise samples using conventional gemmological testing, infrared spectroscopic analysis, Raman spectroscopy, laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), and UV-visible spectroscopic analysis. The aim is to elucidate the mineralogical and spectroscopic characteristics of these samples and provide data support for provenance tracing.Results indicate that the chemical composition of Nanhuatang turquoise is complex, with significant enrichment in Na, Mg, K, Ca, Sc, Ti, V, Cr, Zn, Mo, and Ba. Notably, the concentrations of Ca, Cr, K, Mo, and Ba are considerably higher than those observed in other turquoise deposits. Rare earth element (REE) analysis reveals a left-dipping chondrite-normalized distribution pattern, characterized by low total REE content (ΣREE), relative depletion of light REEs, and relative enrichment of heavy REEs, with significant fractionation between the two groups. Raman spectral analysis showed that the main absorption peaks were located at 3 470 cm-1 (hydroxyl group stretching vibration) and 1 040 cm-1 (phosphate symmetry stretching vibration). UV-Vis absorption spectroscopy demonstrates that the coloration of turquoise is closely related to its chemical composition.The d—d electron jump of Cu2+ ions (670~690 nm absorption band) is a key factor in the blue colouration of turquoise, while the electron jump of Fe3+ ions is located at 428 nm.Based on the above analysis, the paper reveals the geological features of the Nanhuatang turquoise source area, providing data support for conducting turquoise provenance studies.
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WANG Yi, YANG Ming-xing, DUN Jin-han, JIANG Yan, LIU Ling, YUAN Ye. Spectroscopic Characterization of Turquoise From Nanhuatang, Shiyan, Hubei[J]. Spectroscopy and Spectral Analysis, 2025, 45(9): 2467
Received: Jan. 25, 2025
Accepted: Sep. 19, 2025
Published Online: Sep. 19, 2025
The Author Email: YANG Ming-xing (yangc@cug.edu.cn)