Abstract
A new system has been constructed for high temperature transmission electron microscopy (HTTEM) to investigate phase transformation of silicate minerals. This HTTEM system, available up to 1200-1300°C, was successfully applied to high_??_low phase transitions of Ca-poor clinopyroxenes. This phase transition was in-situ observed for the first time under HTTEM and was revealed to be a thermoelastic type of martensitic transformation. Formation process of antiphase boundaries in pigeonite was also in-situ observed during the phase transition under HTTEM.
