Spectroscopic study of natural quartz samples

• Published in: Radiation physics and chemistry (Oxford, England : 1993) England : 1993), 2013-09, Vol.90, p.79-86
• Main Authors: Nunes, Eduardo H.M., Lameiras, Fernando S., Houmard, Manuel, Vasconcelos, Wander L.
• Format: Article
• Language: English
• Subjects: atomic absorption spectrometry; bleaching; Color; electron paramagnetic resonance spectroscopy; Emission analysis; Fourier transform infrared spectroscopy; Fourier transforms; Gamma radiation; Gamma rays; Heat treatment; Inductively coupled plasma; Infrared spectroscopy; quartz; Spectroscopy; Ultraviolet radiation; ultraviolet-visible spectroscopy; X-ray diffraction
• ISSN: 0969-806X
• DOI: 10.1016/j.radphyschem.2013.05.003

In this work we performed a spectroscopic characterization of natural amethyst, citrine, and prasiolite samples from different localities. These materials were examined by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV-visible spectroscopy (UV-vis), electron paramagnetic resonance (EPR), and inductively coupled plasma atomic emission spectrometry (ICP-AES). Samples were used in this study in as-received, gamma-irradiated, UV-irradiated, and heat-treated conditions. We observed the changes in the FTIR, UV-vis, and EPR spectra of these samples as a function of the condition they were analyzed. We noticed that gamma radiation had a great effect on the color of amethyst and citrine samples used in this work. It was observed that light colored samples showed a deepening of their colors upon gamma-irradiation and a bleaching upon heat treatment at 450 degree C. However, we observed that gamma radiation had a slight effect on the color of citrine. UV-irradiations revealed that the coloration of both amethyst and prasiolite can be bleached by UV radiation. On the other hand, the color of citrine was not affected by UV radiation.