The Collaborative International Dictionary of English v.0.48:

Meionite \Mei"o*nite\, n. [Gr. mei`wn smaller. So called in a
   allusion to the low pyramids of the crystals.] (Min.)
   A member of the scapolite group, occuring in glassy crystals
   on Monte Somma, near Naples.
   [1913 Webster]