Near- and Mid Infrared Spectroscopy of the Lithium-Bearing Amphibole Holmquistite from Barraute, Canada

Abstract

The mid-and near infrared spectra of holmquistite, a lithium-containing orthorhombic amphibole, from Barraute (Quebec, Canada) has been measured. The OH stretching region is characterised by bands around 3660, 3645, 3629 and 3613 cm -1 assigned to (3Mg)-OH, (2Mg + Fe 2+ )-OH, (Mg + 2Fe 2+ )-OH and (3Fe 2+ )-OH, respectively. Based on the ratio between the 3645 and 3660 cm -1 bands Fe 2+ /(Fe 2+ + Mg 2+ ) ratios in the M 1 and M 3 sites were determined to be in the range between 0.3 (mid infrared) and 0.4 (Raman). In the near infrared region, two times four bands were observed associated with the four possible combination modes of the four M-OH stretching and bending modes around 4029, 4193, 4323 and 4400 cm -1 and with the four overtones of M-OH stretching modes around 7055, 7091, 7123 and 7155 cm -1 .

Characterisation of the Copper Arsenate Mineral Strashimirite, Cu8(AsO4)4(OH)4·4H2O, by near Infrared Spectroscopy

“…the splitting of both 2 e and 2 t states is the effect of site distortion for the cu 2+ ion that occupies Jahn-teller sites in many copper complexes. [28][29][30][31][32] for cu 2+ the number of bands observable is four and three in rhombic and tetragonal fields, respectively. the energies of the three bands in tetragonal field are related to 2 B 1 ® 2 a 1 , 2 B 1 ® 2 B 2 and 2 B 1 ® 2 e transitions.…”

“…[18][19][20][21][22][23][24][25] frost et al extended this research to study a range of diagenetically related mineral systems. [26][27][28][29][30][31][32][33][34][35] In this research, we are applying nIr spectroscopy to the study of the arsenate minerals from two different origins, namely strashimirite.…”