TEMPERATURE RANGE FOR THE FORMATION OF SODALITE-BEARING ASSEMBLAGES

Abstract

Sodalites are framework aluminosilicates with the general formula Na8Al6Si6O24 · (X)(1–2), where X represents Cl –, Br–, I–, S , C , OH –, and other anions. Sodalites usually crystallize in a cubic structure with space group P43n for chlorine-sodalite and P43 m for sulfate-sodalite (nosean). Sodalite occurs in alkaline igneous rocks and, occasionally, in pegmatites. The greatest diversity of sodalite-group minerals was observed in the Lovozero alkaline massif, where hydroxyl-, chlorine-, and sulfate-bearing sodalites were found.