IR Absorption Spectrum Representation of Turquoise,Treated Turquoise and Imitation

By using the infrared reflection spectrum analysis technique,the filled,pressed,imitated and natural turquoises on gem markets are investigated.The results show that the IR peaks at 2 934~2 924,2 863~2 854 cm^-1 are resulted from the asymmetrical stretching vibration and the symmetrical stretching vibration of CH₂and the strectching vibration of ν(C＝O) peaks lie at 1 739~1 718 cm^-1 in polymer of the treated and imitated turquoises.The imitated truquoises have the characteristic spectra of the asymmetrical stretching vibration and the symmetrical stretching vibration of CH₂,and the vibration of ν(C＝O) and characteristic absorption bands of themselves.But,they lack any typical peaks of stretching vibration of hydroxyl of natural turquoise(3 507,3 465 cm^-1).These typical IR spectra play an important role in distinguishing the treated and imitated turquoises from the natural turquoise.