FELDSPARS AND THEIR PECULIARITIES AS CERAMIC SOLVENTS ¹

ABSTRACT Data are presented to combat the fallacy that the chemical composition of a feldspar is a definite indication of its behavior as a vitrifying agent in ceramic bodies. A general presentation of data on the pure feldspar types and their constitution and mode of occurrence in commercial deposits is made. The effect of solid solution vs. associated or mixed feldspars on the physical properties of feldspars of similar compositions is outlined and the character of associated quartz and muscovite (white mica) is considered. A proposed basis of classification depending on the fusion behavior of the feldspar in the presence of quartz, kaolin, and ball clay is made.