NASA TN D-6980 APPLICATION OF THERMODYNAMICS TO SILICATE CRYSTALLINE SOLUTIONS
i FOREWORD iii ACKNOWLEDGMENTS v SYMBOLS ix 1 THERMODYNAMIC RELATIONS IN CRYSTALLINE SOLUTIONS 1 2 THERMODYNAMIC STABILITY OF A SOLUTION 11 3 COMPOSITION OF COEXISTING PHASES 15 4 MEASUREMENT OF COMPONENT ACTIVITIES BY ANALYSIS OF PHASE DIAGRAMS 25 5 MEASUREMENT OF COMPONENT ACTIVITY USING COMPOSITION OF COEXISTING MINERALS 35 6 ORDER-DISORDER IN Fe-Mg SILICATES 39
MIXING PROPERTIES OF SANIDINE CRYSTALLINE SOLUTIONS: II. CALCULATIONS BASED ON VOLUME DATA1
Analyses of standard deviations of data having restricted ranges of compositions indicates a discontinuity in the voiume-composition curves between 33.7 and 3g.6 mole percent KAlsisos for orville's voiume data. This discontinuity in volume is in the same composition range as a monoclinic-triclinic symmetry change at 2s"c which orville established from plots of 29-values and lattice angles versus composition. A similar analysis of Donnay and Donnay's data led to inconclusive results because the data points are too few and unevenly spaced. Another apparent break in orville's data between 5 and 10 percent KAlSirOs may be related to a ,,fossil,' symmetry change inherited from the temperature of synthesis.
Thorium in monazite sand; separation and determination by precipitation from homogeneous solution
A new method is described which consists of three steps: (1) decomposition of the monazite sand with perchloric acid; (2) separation of thorium and the rare earths by hydrolysis of methyl-oxalate in acid solution; and (3) separation of thorium from the rare earths by hydrolysis of urea in the presence of formic acid. The authors consider the method to be accurate and rapid.