Present bounds on the bulk composition of Mercury: implications for planetary formation processes.

The bulk composition of Mercury is virtually unconstrained by the present meager data set. Compositions ranging from extremely refractory-rich to volatile-rich may be consistent with the present data. The extreme, end-member models, however, are judged implausible because the conditions under which such compositions could be produced are very restrictive and thus improbable. An intermediate, moderately refractory model for the composition of Mercury is presented. Additional data are essential for a better understanding of Mercury's composition.