Pentakaidecahedron

The lacunar pattern of this grain therefore includes six tetragonal and nine hexagonal faces. Relating this to polyhedrons, we find that no pentakaidecahedron with such a combination of faces can exist (see page 199).

The host structure is similar to that of the (n–C₄H₉)₄ N⁺C₆H₅COOH⁻·39.5 H₂O consisting of a tetragonal body-centered arrangement of groups of five face-sharing pentagonal dodecahedra interlinked by tetrakaidecahedra and pentakaidecahedra.

An ideal unit cell consists of ten dodecahedrons, sixteen tetrakaidecahedrons and four pentakaidecahedrons.