Gemmological and Spectral Characteristics of Xenotime from Pakistan

The xenotime from Pakistan mainly develops short columnar crystals with different shades of yellow, glass luster, and is usually transparent to semitransparent. By using conventional gemmological instruments, infrared spectrometer, Raman spectrometer, and ultraviolet-visible spectrometer, the gemmological and spectral characteristics of xenotime from Pakistan were studied. The results show the refractive index of 1.718-1.731, uniaxial positive optical character, medium degree of yellow-dark yellow pleochroism, none fluorescence, and relative density of 4.41-4.65. The xenotime mineral contains many gas-liquid inclusions and flake inclusions that can be found through microscopic observation. The strongest characteristic peak of the infrared spectrum of xenotime is between 1 050-1 072 cm^-1, and there are 1 181, 649, 525 cm^-1and 408 cm^-1 characteristic lines. The strongest characteristic peak of the Raman spectrum is at 998 cm^-1, and the second strongest characteristic peak is near 1 056 cm^-1, and there are many characteristic peaks between 200-700 cm^-1. There are more than 10 characteristic absorption peaks under UV-Visible light, and the maximum absorption peak is around 653 nm. This study shows that the inclusion, infrared spectroscopy, Raman spectroscopy and UV-Visible absorption characteristics are the basis for the identification of natural xenotime.