MAGMATIC FLUORITE AND CONDITIONS OF ITS CRYSTALLIZATION FROM PANTELLERITE MELT

Abstract

Thermometric study showed that fluorite begins to melt in inclusions at 740° to 780°C before dissolving completely at 840° to 890°C. Further heating led to solution of silicate crystals and the anorthoclase rim, to contraction of the fluid phase and, finally, to total homogenization of inclusions at 930° to 1020°C. With one large inclusion we conducted a test on crystallizing its melt. That inclusion, heated to 920°C, was cooled to 750°C and held at this temperature for 4 hr. Consequently, we observed many needle-shaped crystals. To determine the quantitative composition of the melt from which fluorite crystallized, we run a successive study of inclusions heated to different temperatures and then quenched fast. The results are presented in tabular form.