POTASH‐SODA‐LIME FELDSPAR EUTECTIC STUDY*

Abstract

ABSTRACTAn investigation was made of the fusion behavior of the potash feldspar, soda feldspar, and soda‐lime feldspar system, all materials being of commercial grade. The potash feldspar had a pyrometric cone equivalent of cone 9 1/2, the soda feldspar, cone 6 1/2, and the soda‐lime feldspar deformed at cone 11 l/2. Mixtures varying according to the triaxial diagram were made in the form of pyrometric cones. These were fired in groups along with standard Orton cones.The 30% commercial potash fcldspar‐70% commercial soda feldspar mixture reached 6 o'clock deformation when standard Orton cone 6 showed 2 o'clock deformation.The mixture of 62 l/2% commercial potash feldspar with 37 1/2% soda‐lime feldspar reached 6 o'clock deformation when cone 7 showed 1 o'clock deformation, the deformation of the cone 9 1/2 potash feldspar being reduced 3 cones by the addition of the proper percentage of the cone ll 1/2% soda‐lime feldspar.There was an increase in deformation temperatures (no indication of eutectic) in the plagioclase series, soda feldspar to soda‐lime feldspar.The mixture of 30% commercial potash feldspar, 60% commercial soda feldspar, 10% soda‐lime feldspar showed 6 o'clock deformation when cone 6 showed 1 o'clock deformation, this being the lowest temperature at which any member of the system showed 6 o'clock deformation.