Major transition-metal oxide minerals; their electronic structures and the interpretation of mineralogical properties

Simplified electronic-structure models based on molecular orbital calculations are presented for hematite, magnetite, ilmenite, ulvdspinel and chromite. The "one-electron" MO/band-ttreory models are correlated with the properties of these minerals. Spectral reflectivity variations are interpreted from the energies of allowed electronic transitions involving both orbitals dominantly
metal in character and those dominantly oxygen. The influence of electronic structure on limits of solid solution, Vickers hardness and thermochemical properties is also considered. In particular, the contribution to stability of tle main bonding orbitals (chiefly metal 3d and oxygen 2p in character) is assessed. The electronic structures and mineral properties of wiistite, rutile and eskolaite are also briefly reviewed.