The Collaborative International Dictionary of English v.0.48:

Lazulite \Laz"u*lite\, n. [From lazuli : cf. F. lazulite, G.
   lazulith.] (Min.)
   A mineral of a light indigo-blue color, occurring in small
   masses, or in monoclinic crystals; blue spar. It is a hydrous
   phosphate of alumina and magnesia.
   [1913 Webster]