Study on Spectral Characteristics of Scheelite From Xuebaoding, Pingwu County, Sichuan Province, China

The Xuebaoding deposit which locates in Huya Township, Pingwu County, Mianyang City, Sichuan province, produces a kind of big rare orange scheelite with perfect crystal shape that collectors of gemstones and mineral crystals favor. The conventional gemological characteristics, infrared spectroscopy, Raman spectroscopy, ultraviolet-visible spectroscopy, and fluorescence spectroscopy were employed to study the spectral characteristics of five scheelite samples from Xuebaoding in this article in order to clarify the gemological characteristics of scheelite in this area. The typical infrared spectra show that: the fingerprint characteristics absorption in 440 cm(-1) and region 800 similar to 900 cm(-1) is induced by out-of-plane bending vibration andasymmetric stretching vibrations attributed to [WO4](2) tetrahedral groups, respectively. The functional group region (2 000 similar to 3 000 cm(-1)) absorption peaks are related to water. The Raman spectrum scattering main peak at 911 cm i corresponds to the vi symmetric stretching vibration of [WO4](2); the Raman shift located in 797 cm(-1) is caused by v(3) anti-symmetric stretching vibrations of [WO4](2); the low intensity Raman scattering peak at 322 and 400 cm(-1)correspond to the out-of-plane flexural v(2) vibration of [WO4](2); The translational mode of (Ca-O) displays the Raman spectrum scattering peak at 211 cm(-1). The ultraviolet-visible spectrum shows that the deep orange color of scheelite samples from the Xuebaoding deposit is related to absorption peaks at 584, 588, 682, 743, 750, 803 and 874 nm. The ultraviolet-visible spectrum may correspond to the "didymium" which is a compound of Pr and Nd. The 3D fluorescence spectra show that colorless scheelite sample and deep orange scheelite samples have the same main fluorescence peak position and number, which is located in lambda(ex)235 nm/lambda(ex) 455 nm, lambda(ex)250 nm/lambda(em) 490 nm and lambda(ex) 265 nm/lambda(em) 523 nm. In addition to the above-mentioned main fluorescence peaks, the light orange scheelite samples also appear to have a fluorescence peak at lambda(ex)250 nm/lambda(e)m 425 nm.