Spectroscopy and Spectral Analysis, Volume. 44, Issue 6, 1689(2024)

Spectral Characteristics and Analysis of Main and Trace Elements of Scheelite From Xuebaoding

CAO Qin-yuan1... SHI Miao2,3,4,* and MA Shi-yu2 |Show fewer author(s)
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  • 1[in Chinese]
  • 2[in Chinese]
  • 3[in Chinese]
  • 4[in Chinese]
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    Scheelite is a rare gemstone with a massive granular structure, exhibiting a white to light yellow coloration, greasy luster, and obvious fluorescence. The scheelite deposit at Xuebaoding in the Pingwu region of Sichuan Province is a vein-like hydrothermal-type deposit with weak alteration of host rocks. Scheelite produced has a high color saturation, perfect crystal form, and pure color, associated with beryl, cassite and muscovite. The nearly colorless to orange tone scheelite from Xuebaoding was taken as the research object in this study. Comprehensive analysis was conducted using X-ray powder diffraction (XRD), Fourier infrared spectrum analysis, ultraviolet-visible spectrophotometer, laser Raman spectrometer, electron probe, and laser ablation inductively coupled plasma mass spectrometer (LA-ICP-MS). The mineral composition, crystal structure, characteristic identification spectral bands, color-causing ions, as well as the contents of the main and trace elements, rare earth and other chemical components of the nearly colorless to orange tone scheelite were determined by combining mineralogy, spectroscopy and main and trace elements characteristics. The relationship between rare earth element content and color genesis was also discussed. All have to provide the diagnostic basis for identification of nearly colorless to orange tone scheelite from Xuebaoding. The research results demonstrate that scheelite exhibits good crystallinity, displaying a uniform chemical composition without obvious discontinuity. The mineral composition is relatively concentrated, and the accessory minerals are mostly muscovite and illite. Significantly, scheelites typical infrared characteristic peaks were observed at 440, 809 and 870 cm-1, along with a peak at 448 cm-1 related to Ca2+. The spectral peak exhibits higher absorption for deeper color tones. In the same way, the Raman characteristic peak is at 909 cm-1, and the Ca—O lattice vibration peak is at 207 cm-1, with increasing intensity as the color tone deepens. Additionally, the ultraviolet absorption peaks show strong absorption in the orange-yellow region, with peaks around 383, 570, 584 and 804 nm. The nearly colorles scheelite samples only exhibit a peak at 383 nm, while the scheelite sample with a lighter yellow tone demonstrates weak absorption of Fe3+ in the near ultraviolet region. Conversely, the scheelite samples with a deeper yellow tone display strong absorption of Fe3+ in the blue-purple region and the orange tone due to Nd3+. Moreover, the chemical components of scheelite reveal a WO3/CaO mass ratio that approaches or exceeds the ideal value, while the content of the nearly colorless scheelite sample is relatively concentrated. The trace element Fe demonstrates a positive correlation with color tone, whereby the content increases as the yellow tone becomes darker. Nevertheless, the total amount of rare earths varies widely, with an enrichment of light rare earths, significant negative Eu anomalies, and insignificant Ce anomalies. The light yellow tone is influenced by trace elements Si and Fe and the d-d electronic transition of Fe3+. Similarly, the yellow tone is affected by trace elements Mn and Fe, along with the electronic transition of Fe3+. In contrast, the orange tone is significantly impacted by rare earth elements Nd and Sm.

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    CAO Qin-yuan, SHI Miao, MA Shi-yu. Spectral Characteristics and Analysis of Main and Trace Elements of Scheelite From Xuebaoding[J]. Spectroscopy and Spectral Analysis, 2024, 44(6): 1689

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    Paper Information

    Received: Jul. 15, 2023

    Accepted: --

    Published Online: Aug. 28, 2024

    The Author Email: Miao SHI (miaoer727@126.com)

    DOI:10.3964/j.issn.1000-0593(2024)06-1689-08

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