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Exfoliation of Egyptian Blue and Han Blue, Two Alkali Earth Copper Silicate-based Pigments
Published on: April 24, 2014
A vibrational spectroscopic study of the copper bearing silicate mineral luddenite
Ray L Frost1, Andrés López1, Yunfei Xi1
1School of Chemistry, Physics and Mechanical Engineering, Science and Engineering Faculty, Queensland University of Technology, GPO Box 2434, Brisbane, Queensland 4001, Australia.
Abstract:
The molecular structure of the copper-lead silicate mineral luddenite has been analysed using vibrational spectroscopy. The mineral is only one of many silicate minerals containing copper. The intense Raman band at 978 cm(-1) is assigned to the ν1 (A1g) symmetric stretching vibration of Si5O14 units. Raman bands at 1122, 1148 and 1160 cm(-1) are attributed to the ν3 SiO4 antisymmetric stretching vibrations. The bands in the 678-799 cm(-1) are assigned to OSiO bending modes of the (SiO3)n chains. Raman bands at 3317 and 3329 cm(-1) are attributed to water stretching bands. Bands at 3595 and 3629 cm(-1) are associated with the stretching vibrations of hydroxyl units suggesting that hydroxyl units exist in the structure of luddenite.
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