Figure 07. Nph-SiO2-Kls Diagram. This ternary liquidus diagram for the system (NaAlSiO₄)-(SiO₂)-(KAlSiO₄) is based on work by Frank Shairer and Norman Bowen as summarized in Shairer (1950, Fig. 1). There are cotectic curves between Nph_ss and Lct, between Nph_ss and Afs_ss, and between Afs_ss and Trd. There is a carnegieite (Cng)-Nph reaction curve with the carnegieite (NaAlSiO₄) composition outside the Nph-SiO2-Kls triangle. There is also a Lct-Afs_ss reaction curve that becomes a Lct-Afs_ss cotectic at about 1050°C. The Afs_ss-Trd cotectic has low point that is a ternary minimum at about 970°C. The other cotectic curves meet at a ternary eutectic at 1020°C.

Move the slider to see isothermal phase equilibrium sections through the ternary liquidus diagram. These sections are representative approximations because the diagram does not provide equilibrium compositional data for the solids as a function of temperature. The isothermal sections may help you visualize equilibrium crystallization paths for liquid compostions that move either towards the ternary minimum (above the Afs line) or towards the ternary eutectic (below the Afs line).    Return to Previous View