The mean ionization states of 44--260 keV per charge ions observed as bursts in and near the earth's magnetosphere have been determined by using the particle data collected by the University of Maryland experiment on Imp 8. We find that during the period from October 1973 to December 1976 (1) the abundance ratio of heavy ions (Z>2) to alphas ranges from 0.04 to 0.10, with a mean value of 0.08 ¿0.02; (2) the energy spectra of alphas and Z>2 ions in these bursts are adequately represented as exponentials in energy per charge with e-folding energies of 30--50 keV/Q; (3) the e-folding energies of both alpha particles and heavier ions are generally harder upstream from the bow shock than in the magnetotail and magnetosheath; and (4) the elemental abundances and ionization state distribution of the heavy ions are consistent with those of the corona at an equilibrium coronal temperature of 1--2¿106 K, which tends to support a solar wind origin for these particles.