The Collaborative International Dictionary of English v.0.48:

Harmotome \Har"mo*tome\ (-m[-o]*t[=o]m), n. [Gr. "armo`s a joint
   + te`mnein to cut: cf. F. harmotome.] (Min.)
   A hydrous silicate of alumina and baryta, occurring usually
   in white cruciform crystals; cross-stone.
   [1913 Webster]

   Note: A related mineral, called lime harmotome, and
         Phillipsite, contains lime in place of baryta. --Dana.
         [1913 Webster]