Revision based on time stamp , RR 1 Al diffusion in quartz 2 3

17 Aluminum diffusion in synthetic and natural quartz was characterized under anhydrous 18 conditions at 1 atmosphere and temperatures from 700 to 950 ̊C. Experiments were 19 carried out on polished quartz slabs immersed in fine-grained powder of spodumene or 20 K-feldspar. Diffusion profiles were measured using Nuclear Reaction Analysis (NRA) 21 and yield the following Arrhenius parameters: 22 23 D Al (all orientations) = 2.48 x 10 -11 exp(-199 ± 10 kJ.mol/RT)ms, where log D0 = 24 10.6 ± 0.55 25 26 The diffusivity of Al through the quartz lattice is sufficiently slow (e.g., akin to Ti) that 27 diffusive modification or loss of Al in magmatic or metamorphic quartz is unlikely in all 28 but the most extreme temperature-time conditions seen in natural systems. In other 29