Phase Relations of the Hydroxyl Felspathoids in the System NaAlSiO4-NaOH-H20

Abstract

<p>A study was made of the phase relationships in the system NaAlSiO₄-NaOH-H₂O, at 15,000 p.s.i. and at 450°C, 520°C, 600°C and 700°C. The following phases were found and characterised: hydroxyl varieties of nosean, sodalite and cancrinite, with formulae approximating to 3NaAlSiO₄.NaOH.xH₂O, 1x1.5, sodic nepheline and phase X, apparently a previously unreported phase, with composition approaching Na₄Al₂Si₂O₉. Approximate phase diagrams were deduced for the four temperatures.</p>