INCREASED “CRYSTALLINITY” OF Na-FLUORTAENIOLITE BY HYDROTHERMAL ANNEALING

Abstract

An imnrovement in the “crystallinity” of an industrially synthesized Nafluortaeniolite was performed by hydrothermal annealing with pure water or NaOH solutions. The temperatures and pressure applied were 300, 450 and 600°C, and 100MPa, respectively. The run duration was 7 days. By hydrothermal annealing, the particles of Na-fluortaeniolite less than about 21Lm disappeared and others grew to have the euhedral shape common to micas. The improvements in the size, form and perfection of crystals resulted from a pure water treatments, especially that at 600°C. The hydrothermal annealing with NaOH solution showed a similar effect but produced some second phases.