The Collaborative International Dictionary of English v.0.48:

Leucitoid \Leu"ci*toid\ (l[=u]"s[i^]*toid), n. [Leucite + -oid.]
   (Crystallog.)
   The trapezohedron or tetragonal trisoctahedron; -- so called
   as being the form of the mineral leucite.
   [1913 Webster] Leuco