@article{lameiras_nunes_vasconcelos_2009,  title={Infrared and chemical characterization of natural amethysts and prasiolites colored by irradiation},  volume={12},  ISSN={1516-1439},  url={https://doi.org/10.1590/S1516-14392009000300011},  DOI={10.1590/S1516-14392009000300011},  number={3},  journal={Materials Research},  publisher={ABM, ABC, ABPol},  author={Lameiras, Fernando Soares and Nunes, Eduardo Henrique Martins and Vasconcelos, Wander Luiz},  year={2009},  month={Jul},  pages={315–320} }