In situ high-temperature behaviour and breakdown conditions of uvite at room pressure

The thermal behaviour of an uvite from San Piero in Campo (Elba Island, Italy) was investigated at room pressure through in situ high-temperature powder X-ray diffraction (PXRD), until the breakdown conditions were reached. The variation of uvite structural parameters (unit-cell parameters and mean bond distances) was monitored together with site occupancies and we observed the thermally induced Fe oxidation process counterbalanced by (OH)(-) deprotonation, which starts at 450 degrees C and is completed at 650 degrees C. The uvite breakdown reaction occurs between 800 and 900 degrees C. The breakdown products were identified at room temperature by PXRD and the breakdown reaction can be described as follows: tourmaline -> indialite + yuanfuliite + plagioclase + boron-mullite phase + hematite.

Automated summary

In this study, the thermal behavior of an uvite from San Piero in Campo was investigated using in situ high-temperature powder X-ray diffraction. The results showed that a thermally induced Fe oxidation process and deprotonation occurred in the uvite from 450 to 650 degrees C. The breakdown reaction of uvite occurred between 800 and 900 degrees C, resulting in the formation of indialite, yuanfuliite, plagioclase, boron-mullite phase, and hematite as the breakdown products.