The role of rare metal preconcentration in granitic melts is generally recognized as a prerequisite to form magmatic-hydrothermal deposits. The fate of rare metals - i.e. whether they are concentrated in granitic melts and transferred to upper crustal levels or sequestered in the restite - and factors of enrichment might strongly be affected by melting mechanisms. Yet, rare metal behaviour during partial melting has been little addressed experimentally, and systematic studies determining melting reactions, mineral assemblage and melt compositions as a function of pressure (P), temperature (T), oxygen fugacity (fO2) and volatiles, remain notably absent. To explore the influence of volatiles (H2O-CO2, F), partial melting experiments were conducted for 14 days in internally heated pressure vessels at 400 MPa, different T (750, 800, 850 °C) and fO2 (QFM-1 to QFM+3). To preserve melting textures and to test for the effect of mica composition, starting materials were drilled cores from a biotite-rich paragneiss and a muscovite-rich orthogneiss from the metamorphic series of La Dronne (French Massif Central) as well as a zinnwaldite- (> 4 wt% F) and coltan-bearing migmatitic gneiss from Abu Rusheid (Eastern Desert, Egypt). Mica dehydration-“defluorination” experiments were conducted on the migmatitic gneiss. Furthermore, fluid-present, H2O-undersaturated (10 wt% H2O-CO2) experiments were conducted on all starting materials with variable XCO2 (0.2, 0.4, 0.6). Preliminary results show that mica-dehydration-“defluorination” is almost congruent - in contrast with mica-dehydration melting in gneisses from La Dronne - implying that all rare metals released from micas breakdown are partitioned to the melt. At 850°C, the reaction produces a slightly peraluminous granitic melt (A/CNK ~ 1.13) enriched in F (1.9 ± 0.4 wt%) and Nb2O5 (0.05 ± 0.03 wt%). Accessory minerals contribute locally but significantly to rare metal enrichment in the melt (Nb2O5: 0.33 ± 0.2 wt%; SnO2: 2.88-12.7 wt%). Further analyses are in progress.