  Strangelets (stable lumps of quark matter) can have masses and charges much
higher than those of nuclei, but have very low charge-to-mass ratios. This is
confirmed in a relativistic Thomas-Fermi model. The high charge allows
astrophysical strangelet acceleration to energies orders of magnitude higher
than for protons. In addition, strangelets are much less susceptible to the
interactions with the cosmic microwave background that suppress the flux of
cosmic ray protons and nuclei above energies of $10^{19}$--$10^{20}$ eV (the
GZK-cutoff). This makes strangelets an interesting possibility for explaining
ultra-high energy cosmic rays.
