The System Silica‐Sodium Tetraborate

Abstract

The phase relations were established for the system silica‐sodium tetraborate. The silica liquidus curve exhibits strong upward concavity but shows no flattening. The tridymite‐cristobalite transformation occurred at 1410°± 10°C. A lowering of the α to β quartz inversion temperature of about 9°C was detected. Primary crystal habits are discussed. The region of metastable subliquidus immiscibility is also discussed and the nature of initial crystallization of the silica‐rich liquid is shown.