Wadsleyite

Wadsleyite is a high-pressure phase of Mg₂SiO₄ and is polymorphous with the olivine phase forsterite. An orthorhombic mineral with the formula β-Mg₂SiO₄, it was first found in nature in the Peace River meteorite from Alberta, Canada. It is formed by a phase transformation from forsterite (α-Mg₂SiO₄) under increasing pressure and eventually transforms into spinel-structured ringwoodite (γ-Mg₂SiO₄) as pressure increases further. The structure can take up a limited amount of other bivalent cations instead of magnesium, but contrary to the α and γ structures, a β structure with the sum formula Fe₂SiO₄ is not thermodynamically stable. Its cell parameters are approximately a = 5.7 Å, b = 11.7 Å and c = 8.24 Å.