Structures of [alpha]- and [beta]-TCP have been classified as glaserite-type, named after the mineral glaserite, [K.sub.3]Na[([SO.sub.4]).sub.2] (30).
Ca[K.sub.3]H[([PO.sub.4]).sub.2] can be considered to have the closest similarity to the glaserite structure.
The arrangement of these columns in a pseudohexagonal form is similar to that of glaserite. However, since [alpha]-TCP does not have a 2:1 cation-anion ratio, its emulation of the glaserite structure requires cation vacancies with the formula [Ca.sub.3][][([PO.sub.4]).sub.2] where [] = vacancy.
The packing of the Ca-[HPO.sub.4] chains or the corrugated sheets results in several possible pseudohexagonal arrangements of the [Ca.sup.2+] and/or [PO.sub.4.sup.3-] columns, reminiscent of the glaserite structure.
However, a closer examination of the structures would reveal that all calcium orthophosphates, listed here, can be included as distorted glaserite type structures, but with varying degrees of distortion.