The Collaborative International Dictionary of English v.0.48:

Datolite \Dat"o*lite\, n. [From. Gr. ? to divide + -lite; in
   allusion to the granular structure of a massive variety.]
   (Min.)
   A borosilicate of lime commonly occuring in glassy,, greenish
   crystals. [Written also datholite.]
   [1913 Webster]