Figure 5.23. NaAlSi₃O₈-CaAl₂Si₂O₈ equilibrium phase diagram. Phases at equilibrium for the chemical system NaAlSi₃O₈-CaAl₂Si₂O₈ are shown as a function of chemical composition (weight percent CaAl₂Si₂O₈) and temperature. The orange area indicates temperatures and compositions for which a single phase, silicate liquid (magma), is present at equilibrium. The liquid only region is bounded by a single saturation curve for plagioclase (Pl). Plagioclase is a solid solution phase. The green area indicates temperatures and compositions for which a single phase, plagioclase, is present at equilibrium. The plagioclase only region is bounded by a single saturation curve for liquid (Liq). Areas that have the horizontal line pattern indicate temperatures and compositions for which two phases, plagioclase and silicate liquid, are in equilibrium.

Click on he "Show Phase %" button and mouseover the diagram to see the equilibrium assemblage and phase compositions at each temperature and bulk chemical composition. This diagram was drawn from data obtained in high temperature experiments by Bowen (1912) and Shairer (1960), and revised by Morse (2015).

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