Crystallization temperature of wyomingite from Leucite Hills

Wyomingite collected from Leucite Hills is composed mainly of leucite, diopside, phlogopite, and small amounts of apatite, calcite, magnetite and rare amphibole, and is characterized by very high content of potash. Thermal experiments at atmospheric pressure indicate that the liquidus phase is always diopside with liquidus temperature of 1320 °C, and solidus temperature is about 1000 °C. Various kinds of melt inclusions are abundant in all constituent minerals. They comprise mono-phase (glass only), two-phase (gas+glass), three-phase (gas+glass+one crystalline phase) and multi-phase (gas+glass+more than two crystalline phases) inclusions. Thermal experiments have been made on these inclusions in phlogopite, diopside, and leucite in order to estimate the temperature of crystallization by homogenizing these inclusions. The results show that the crystallization of wyomingite began with formation of phlogopite accompanied by diopside at 1270 °C. Although diopside ceased crystallization at 1220 °C recurrent crystallization of phlogopite was noticed between 1120 ° and 1040 °C. Leucite crystallized out abundantly between 1250 ° and 1150 °C. Complete solidification of wyomingite occurred at about 1000 °C.