Caracterização da Esmeralda de Pirenópolis (Goiás, Brasil Central) por Espectroscopia no Infravermelho (Ftir)

The infrared spectra of two natural samples of powdered emerald from Pirenópolis (Goiás State, Central Brazil) were measured at room temperature (~ 20ºC). Water molecules occur in two different configurations. Three absorption peaks (3656, 3592 and 1624 cm-1) record the vibrations of the type-II H2O. The peak absorption at 3691 cm-1 is assigned to type- I H2O vibrations. In addition, CO2 (2358 cm-1) and CH4 (2927-2925 cm-1) molecules were also detected in the FTIR spectra. These data can be applied to distinguish the Pirenópolis gem from the other Brazilian emeralds as well as its synthetic equivalents