transition aluminas, aluminum salts, and solidification from melts. Less common methods are: hydrothermal synthesis at high pressure, vapor-phase transition, and burning aluminum in oxygen (Wartenberg ...

undergoes a phase transition to a CaCl 2-type phase, when it contains water and alumina. The CaCl 2-type aluminous silica can hold by more than 10 times water than other lower mantle minerals ...