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Electron microprobe analyses of major- and minor-element oxide components for two glassed samples of natural KLB-1 peridotite are presented. One glass was made with the aid of a phosphate flux, and the second glass was made by laser melting of aerodynamically levitated spheroids resulting in homogeneous silicate glass beads. For unknown reasons, the silicate-phosphate glass yields compositions that are incompatible with the composition of KLB-1 peridotite. However, analysis of the glass bead formed by laser synthesis is believed to give an accurate representation of the composition of KLB-1 peridotite, except for minor loss of [Na.sub.2]O owing to volatilization. The new data resolve conflicting FeO, CaO, and Ti[O.sub.2] values from two older measurements present in the literature. Mass-balance calculations using the new composition measurement combined with new analyses of the mineral compositions in KLB-1 result in a lower sum of squares of the residuals than those using the older measurements. There are appreciable differences in calculated modes from partial-melting experiments of KLB-1 when calculated using older KLB-1 analyses or our new analysis. Keywords: Peridotite, KLB-1, microprobe, mantle, levitating/laser fusion

Experimental brackets on the melting temperature of high albite (NaAl[Si.sub.3][O.sub.8]) were determined at 2.33 [+ or -] 0.03 GPa (1360-1370 [degrees]C) and 2.79 [+ or -] 0.03 GPa (1370-1389 [degrees]C) in a piston-cylinder apparatus. All run products that quenched to a glass were analyzed by Fourier-transform infrared spectroscopy and found to contain [less than or equal to] 500 ppm [H.sub.2]O. In addition, new X-ray diffraction experiments on fully disordered albite are reported to 7.6 GPa; the fitted results lead to a zero-pressure bulk modulus ([K.sub.0]) of 56.4 [+ or -] 0.7 and a pressure derivative ([K.sup.'.sub.0]) of 3.9 [+ or -] 0.3 in a third-order Birch-Murnaghan equation of state. Revised values for the enthalpy and entropy of fusion of high albite at one bar and 1100 [degrees]C [[DELTA][H.sub.Tf] = 64.5 [+ or -] 2.1 kJ/tool and [DELTA][S.sub.Tf]= 47.0 J/(mol*K)] are recommended on the basis of improved heat capacity equations for NaAl[Si.sub.3][O.sub.8] glass and liquid. On the basis of these new results on the fusion curve and thermodynamic data for high albite, the pressure dependence of the NaAl[Si.sub.3][O.sub.8] liquid compressibility ([K.sup.'.sub.0]) is constrained to be 10.8 [+ or -] 1.5 in a third-order Birch-Murnaghan equation of state. The uncertainty in [K.sup.'.sub.0] of [+ or -] 1.5 contributes an error to melt density at 3 GPa (2.543 [+ or -] 0.010 g/[cm.sup.3] at 1500[degrees]C) of [+ or -] 0.4%. Keywords: Compressibility measurements, albite, high-pressure studies, high-temperature studies, phase equilibria, thermodynamics

Experimental brackets on the melting temperature of high albite (NaAlSi3O8) were determined at 2.33 ± 0.03 GPa (1360-1370 °C) and 2.79 ± 0.03 GPa (1370.1389 °C) in a piston-cylinder apparatus. All run products that quenched to a glass were analyzed by Fourier-transform infrared spectroscopy and found to contain ≤500 ppm H2O. In addition, new X-ray diffraction experiments on fully disordered albite are reported to 7.6 GPa; the fitted results lead to a zero-pressure bulk modulus (K0) of 56.4 ± 0.7 and a pressure derivative (K'0) of 3.9 ± 0.3 in a third-order Birch-Murnaghan equation of state. Revised values for the enthalpy and entropy of fusion of high albite at one bar and 1100 °C [ΔHTf = 64.5 ± 2.1 kJ/mol and ΔSTf = 47.0 J/(mol·K)] are recommended on the basis of improved heat capacity equations for NaAlSi3O8 glass and liquid. On the basis of these new results on the fusion curve and thermodynamic data for high albite, the pressure dependence of the NaAlSi3O8 liquid compressibility (K'0) is constrained to be 10.8 ± 1.5 in a third-order Birch-Murnaghan equation of state. The uncertainty in K0 ' of ± 1.5 contributes an error to melt density at 3 GPa (2.543 ± 0.010 g/cm³ at 1500 °C) of ± 0.4%. [ABSTRACT FROM AUTHOR]