The geometries of Mg2SiO4, Mg2GeO4, Al2MgO4, and Ga2MgO4 spinels have been correctly calculated using the periodic Hartree-Fock method at core pseudopotential level. The bonding properties are studied on the basis of electron population analysis and electron density. The band structure and density of states have been computed and are discussed. The bulk modulus and its pressure derivative of each compound have been derived. The structures yielded by our calculations are a little bit too stiff. Different compression mechanisms are proposed for, on the one hand, Mg2SiO4 and Mg2GeO4 and, on the other hand, Al2MgO4 and Ga2MgO4. ¿ American Geophysical Union 1991