Raman spectroscopic study of the molybdate mineral szenicsite and compared with other paragenetically related molybdate minerals

Abstract

The molybdate-bearing mineral szenicsite, Cu3(MoO4)(OH)4, has been studied by Raman and infrared spectroscopy. A comparison of the Raman spectra is made with those of the closely related molybdate-bearing minerals, wulfenite, powellite, lindgrenite, and iriginite, which show common paragenesis. The Raman spectrum of szenicsite displays an intense, sharp band at 898 cm-1, attributed to the 1 symmetric stretching vibration of the MoO4 units. The position of this particular band may be compared with the values of 871 cm-1 for wulfenite and scheelite and 879 cm-1 for powellite. Two Raman bands are observed at 827 and 801 cm-1 for szenicsite, which are assigned to the 3(Eg) vibrational mode of the molybdate anion. The two MO4 2 modes are observed at 349 (Bg) and 308 cm-1 (Ag). The Raman band at 408 cm-1 for szenicsite is assigned to the 4(Eg) band. The Raman spectra are assigned according to a factor group analysis and are related to the structure of the minerals. The various minerals mentioned have characteristically different Raman spectra.