The structure of ringwoodite, (Mg,Fe)2SiO4 (gamma phase)

oxygen atom O
iron atom Fe or magnesium atom Mg
silicon atome Si
Crystallographic system: cubic.
Molar volume: 39,65 cm3/mol
Under high pressure, ringwoodite decomposes into silicate perovskite and magnesiowüstite, whose properties are completely different. This explain the observed discontinuity between the upper and lower mantle of the Earth. At lower pressure, it transforms into wadsleyite.

Copyright © 2001 Sébastien Merkel