Abstract
Molten high-temperature solvents can provide major kinetic advantages in phase equilibrium studies of silicate systems, by markedly enhancing rates of crystal growth and chemical reaction. Experience gained in a study of cation partitioning between ortho-and clinopyroxene at low temperatures and atmospheric pressure suggests that an ideal solvent would combine the following properties: high solubilities for component oxides of silicates, with minimum temperature dependence; no formation of oxide-solvent compounds with melting points above that of the pure solvent; minimal incorporation of solvent components into the crystalline phases of interest; ease of chemical separation of crystalline phases from quenched solvent-rich melt; low volatility and viscosity; density close to that of the crystalline phases; and high surface tension against encapsulation materials, typically platinum. Maximum kinetic benefits of the technique are derived only when the composition of saturated solvent-rich melt is carefully determined as a function of temperature, so that melt-to-crystal ratios in experimental charges can be raised to high values. V2O5 is one solvent suitable for studies involving olivine, pyroxenes, and plagioclase in the system CaO-MgO-Al2O3-SiO2 and its subsystems.
Published Version
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