Abstract Using conventional gemological methods, energy dispersive X-ray fluorescence spectrometer，laser Raman spectrometer, Fourier transform infrared spectrometer and fluorescence spectrometer to study the gemological characteristics of filled morganite and to explore effective non-destructive identification method of filling treated morganites. The results show that the refractive index of filled morganites (1.57) is slightly less than that of natural morganites. The SG values of the filled morganites range from 2.71 to 2.76. The natural morganites do not emit light under neither long-wave or short-wave UV radiation, but filled morganites show weak to medium white fluorescence under UV radiation. And the fluorescence of some samples is distributed along the fractures. After zooming in, fine reticular open cracks can be seen on the surface of partially filled morganites, and traces of glue filling can be seen in the cracks. Energy dispersive X-ray fluorescence spectrometer (EDXRF) shows Si, Al, Rb, Cs and other elements in filled morganites and natural morganites. The difference of Raman spectra between natural morganites and filled morganites is not obvious, and the effect of laser Raman spectrometer on distinguishing natural morganite and filled morganite is not obvious. The FTIR spectra of natural morganites are mainly in 1 300~400 cm-1, which is attributed to the structural vibration of Si—O—Si ring, Be—O and Al—O; in the 4 000~2 000 cm-1 functional group region, there is 2 359 cm-1 absorption peaks produced by CO2, 3 110 and 3 168 cm-1 absorption peaks produced by NaH. In addition to the vibration absorption of morganite itself, the absorptions of (—CH3—), (—CH2—) are common at 2 870, 2 930 and 2 965 cm-1, filled morganites have the absorption caused by benzene ring exists at 3 035 and 3 057 cm-1. Three-dimensional fluorescence spectrometer analysis shows that the fluorescence of natural morganites is very weak, without a characteristic fluorescence center, and the relative intensity is less than 500; the fluorescence centers of filled morganites are mainly single fluorescence center about 410 nm and double fluorescence center of 440 and 465 nm, with relative intensities exceeding 2 000. The relative intensity of the fluorescence center of filled morganite is significantly higher than that of natural morganite, which is attributed to the aromatic compounds in organic gum added during the filling process. Through Fourier transform infrared spectrometer and fluorescence spectrometer test, the spectrum analysis can be used as an effective and rapid non-destructive detection method to distinguish natural morganites and filling treated morganites.
Key words：Morganite; Filling treatment; Infrared spectrum; Three dimensional fluorescence spectrum
WU Yan-han,CHEN Quan-li*,ZHAO An-di, et al. Study on the Gemmological Characteristics of Filled Morganite[J]. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2022, 42(02): 575-581.
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