KAlSiO4-SiO2 equilibrium phase diagram. This diagram has five mineral phases: kalsilite (Kls - KAlSiO4), leucite (Lct - KAl2Si2O6), sanidine (Sa - KAlSi3O8), tridymite (Trd - SiO2), and cristobalite (Crd - SiO2). This diagram was determined experimentally by Schairer and Bowen (1938, 1955) using data from Kracek, Bowen, and Morey (1929) at atmospheric pressure (1 bar).