Elevated concentrations of P<sup^b>2O<s<sup^b>5<sup > ^{of 2-12 wt<}sup>% ^absol<sup^te ^were ^{observed in t} are enriched towards the surfaces in some cases and elemental correlations suggest precipitation of a crystalline calcium phosphate with a stoichiometry close to CaO . P₂O₅. Scanning electron microscopy with X-ray mapping showed P₂O₅ to be dispersed in the ceramic matrix on a very fine scale, while X-ray diffraction detected no crystalline phosphate. Parallels are drawn with the precipitation of phosphate in the surfaces of weathered glass. It is concluded that the amorphous phases produced on firing behave as chemically-active substrates which facilitate the adsorption or precipitation of very fine-grained calcium phosphate from the burial environment. See also AATA 20-1992. -- AATA