Thermal Behavior (–180 ≤ T ≤ 1000°C) of Magnesium Orthosilicate Hydroxylclinohumite Mg5(SiO4)2(OH,F)2

Abstract

Hydroxylclinohumite Mg₅(SiO₄)₂(OH,F)₂ is a common monoclinic orthosilicate of the humite group, which, on the one hand, is a prototype of promising materials, and, on the other hand, is an important source of information about both the transport and the presence of water in the Earth’s mantle, and therefore studying its thermal behavior is of particular interest. In this paper, the mineral is studied by powder X-ray diffraction for the first time in a wide temperature range (–180 ≤ T ≤ 1000°C). The temperature limits for the existence of the phase are established, the principal values of the thermal expansion tensor are calculated, and a structural interpretation of thermal expansion is given.