Barium iodoapatite would have the formula,
Ba5(PO4)5I if it could be formed. Barium iodoapatite,
which has not been prepared, would have a small positive
Gibbs energy of dissolution, and a small enthalpy of
formation. This is probably due to the large size of the
I- ion as it would enter the lattice. Speculations on the
existence of a possible fifth member of the alkaline earth
apatite family, Iodoapatite, have been withdrawn due to
energetic considerations. Whether an oxy-iodo-apatite,
similar to the calcium analogue exists remains speculative.
