Abstract
H2O is an important volatile material in the Earth, and it affects the physical properties (e. g. density, elastic velocity, viscosity, rheobgical property, diffusion, electrical conductivity and melting temperature) of the Earth's materials. Recently, it has been darified that significant amounts of H2O can be accommodated in β and γ phases of olivine, which means that the mantle transition zone has the potential of being a water reservoir in the Earth. In this paper, I review the H2O contents, lattice parameters and elastic properties of hydrous β and γ phases, the effect of H2O on the phase transformation of olivine, and the possibilities of water transportation into the mantle transition zone are discussed on the basis of these experimental data.
