Sodium-alum.imun and potassium-aluminum silicates are among the more important rock-forming minerals of the earth's crust. They also appear as constituents of some metallurgical slags and of some refractory materials. Consequently, knowledge of their thermodynamic properties is interesting and valuable from several viewpoints.
This paper reports experimental determinations of the low-temperature heat capacities and entropies at 298.1EP K. of albite, jadeite, and nephelite in the sodium-aluminum silicate series and of adularia, ferriferous orthoclase, leucite, and kaliophilite in the potassium-aluminum silicate series. Also, high-temperature heat-content and entropy increments about 298.16 °K. are reported for albite, jadeite, nephelite, and carnegieite in the sodium-aluminum silicate series. Except for a few high-temperature heat-content values for albite, all these data are available for the first time.
The natural formation of jadeite has been a matter of discussion for some years, and attempts at thermodynamic treatment have been hampered by lack of some of the requisite data. This paper supplies the previously missing, necessary information for proper thermodynamic consideration of three reactions by which jadeite conceivably could be formed. These new data and pertinent values from the literature are combined to evaluate the possibilities of the reactions:
Albite+ nephelite = 2 jadeite,
albite = jadeite + quartz,
nephelite + quartz = jadeite.