FLUORINE MOBILIZATION AND BONDING AT MAGM ATIC AND POSTMAGMATIC STAGES IN RARE-METAL GRANITES - EVIDENCE FROM THE HOMRAT-AKAREM DEPOSIT (EGYPT)

We studied the behavior of F at the magmatic and postmagmatic stages o f rare-metal granite evolution and the possible genetic relations betw een rare-metal granites and fluorite mineralization by means of thermo barogeochemistry and thermodynamic calculations based on the data for the Homrat Akarem (Egypt) rare-metal granite and vein fluorite. Topaz is shown to be stable in assemblage with quartz, microcline, and low-C a plagioclase at temperatures higher than 350 degrees C, to give way t o fluorite at lower temperatures. The mineralogic peculiarity of the g ranite in question and our study of inclusions in quartz and fluorite corroborate the data we obtained by calculations.