Comparative analysis of quartz treated with gamma radiation originated from the hydrothermal geodes of the Paran?? Basin (Artigas-Uruguay region), with quartz generated in the hydrothermal veins of Serra do Espinha??o (Curvelo-MG and Brejinho-BA regions)

• Autor(a) principal: ENOKIHARA, CYRO T.
• Data de Publicação: 2020
• Outros Autores: SCHULTZ-GUTTLER, RAINER A., RELA, PAULO R., INTERNATIONAL NUCLEAR ATLANTIC CONFERENCE
• Tipo de documento: Artigo de conferência
• Título da fonte: Repositório Institucional do IPEN
• Texto Completo: http://repositorio.ipen.br/handle/123456789/30621
• topic: chemical analysis; cobalt 60; color; comparative evaluations; defects; fourier transformation; gamma radiation; icp mass spectroscopy; infrared spectra; infrared spectrometers; irradiation; quartz; quartzites; ultraviolet radiation; water

In Brazil, hydrothermal quartz may be found in the geodes of the basaltic rocks of the Paran?? Basin and in the vein systems of quartzites of the Serra do Espinha??o. The quartz of hydrothermal origin of the Paran?? Basin contains a great amount of structurally bound water in the form of molecular water, silanol, hydroxyl and abundant growth defects that are responsible for the green color formed by irradiation. To register the influence of water in the formation of the green color in the quartz of the Paran?? Basin, quartz samples from the following regions were analyzed: Artigas, located in the Paran?? Basin, Curvelo and Brejinho located in Serra do Espinha??o. The quartz from Artigas, formed at low temperature, has high concentration of molecular water and silanol and a greater amount of Fe than Al. The quartz from Curvelo with Al, but, without water molecular and silanol was formed by intermediate temperature and the quartz from Brejinho has very little Al, Fe and a small silanol and molecular water content. To characterize these samples, ICP and NIR-FTIR spectroscopic measurements have been taken, together with water loss techniques and color stability, by UV treatment and heating. The analysis by FTIR spectrometry of Artigas quartz samples shows strong absorptions of H2O and Si-OH, respectively, near the regions of 5300 cm-1 and 4500 cm-1. This content of molecular water and silanol in hydrothermal quartz of Artigas is responsible for the formation of NBOHC defects that produce, by gamma radiation, the green color.