40Ar/39Ar and K-Ar geochronological evidence for two periods (2 Ga and 650 to 500 Ma) of emerald formation in Brazil Ribeiro-Althoff, A.M. Cheilletz, A. /Giuliani, Gaston Féraud, G. Barbosa Camacho, G. Zimmermann, J.L. MINERAL BERYLIUM DATATION ANALYSE ISOTOPIQUE MINERALISATION GISEMENT ENDOGENE EMERAUDE 1997 text https://www.documentation.ird.fr/hor/fdi:010059692 fdi:010059692 Ribeiro-Althoff A.M., Cheilletz A., Giuliani Gaston, Féraud G., Barbosa Camacho G., Zimmermann J.L.. 40Ar/39Ar and K-Ar geochronological evidence for two periods (2 Ga and 650 to 500 Ma) of emerald formation in Brazil. 1997, 39 (10), 924-937 EN BRESIL