Infrared absorption spectra of serpentine cat’s eye from Sichuan Province of China

Abstract

Infrared (IR) absorption spectra and X-ray powder diffraction (XRD) patterns of serpentine cat’s eye from Sichuan Province have been investigated, and infrared absorption bands of the serpentine have been assigned in this paper. The results indicate that the bands near 3 600–3 700 cm−1 belong to the stretching absorption band ν OH, the bands in 948–1100 cm−1 are assigned to the stretching vibrating band ν Si-O, and the bands at 600 570 and 440 cm−1 respectively belong to the bending vibration band u0H, ν OH, δMg-O and δ Si-O. The serpentine cat’s eye includes two types: chrysotile and antigorite. Chrysotile has a sharp and intensive band at 3 688 cm−1 and a weak band at 3 643 cm−1, while antigorite has only one intensive band in the region. At vibration band ν Si-O, chrysotile and antigorite have a similar feature at 1 071 cm−1, but the band at 980 cm−1 in antigorite has been split into two bands in chrysotile-a strong one at 1 027 cm−1 and a weak one at 949 cm−1. In addition, antigorite has a characteristic bending vibrating band δ Mg-O at 570 cm−1. Based on the analysis of the feature of crystal structure, their IR differences are well explained.