Resumen de Composición de las biotitas de las cortlanditas de la Sierra de Gredos, Sistema Central español.

Ignacio Moreno-Ventas Bravo, Antonio Castro Dorado

• Biotites from cortlanditic rocks of the Sierra de Gredos (Central System) were analyzed with the microprobe. The first results of this study are presented here. These include a brief discussion about the dominant coupled substitutions as a method to calculate the ferric iron in the molecula- The studied micas are phlogopites in which the cation substitutions are dominated by Ti and Al