The objective of this work is to identify interrelations among mineral structure, bonding, physical properties and stability through the study of high-pressure minerals in the system CaO-MgO-FeO-Al2O3-SiO2-H2O. Several research disciplines, including crystal chemistry and crystallography, vibrational spectroscopy, single-crystal synthesis and solid-state theory, will be applied to well-characterized samples from this group of minerals. A unique feature of this research will be the application of newly-developed techniques for studying single- crystals to hydrostatic pressures of 500 kbar (50 GPa) in a diamond-anvil cell with hydrogen or rare gases (helium, neon or argon) as pressure-transmitting medium. Structural variations with pressure will be studied by x-ray crystallographic techniques; high-pressure structures up to the 500 kbar pressure range will be performed for the first time. Computational methods based on density functional theory will be used to calculate structure, lattice dynamics, equations of state, and thermodynamic functions for the important end member oxide and silicate minerals in the system.