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b"The effect of F on the glass transition behavior of albite, diopside, and four other silicate\\nmelts has been investigated using scanning calorimetry. The addition of F to all silicate\\nmelts investigated results in a strong, nonlinear decrease of the glass transition temperature\\n(Z' as recorded by the peak temperatures of heat capacity). The decreases observed extrapolate\\nconsistently to published fluoride glass transition temperatures. The largest Z,\\ndecrease is observed for albite-FrO-, melts (AT = 250 \\xb0C at 6 wt%F ). The effect of F is\\nsimilar to that previously observed for HrO (Taniguchi, 1981).\\nPhysical properties of low-temperature silicate liquids are a valuable constraint on lowtemperature\\npetrogenetic processes in granite and pegmatite petrogenesis. Low-temperature\\nwiscosities can be estimated from the glass transition data. These data are combined\\nwith previously published high-temperature, concentric-cylinder viscosity data to obtain\\na much more complete description of the temperature dependence of viscosity for these\\nmelts.\\nThe present data, obtained on supercooled liquids close to the glass transition, are of\\nspecial significance because it is at the glass transition that silicate glass structures are\\nfrozen. A separate multinuclear NMR study of glasses quenched from these experiments\\nhas shown that the predominant coordination of F in albite glass is octahedral to Al. The\\ncoordination state of F does not appear to be concentration dependent, and thus the\\nstructural origin of the nonlinear Z, decrease does not arise from such a mechanism."