The Collaborative International Dictionary of English v.0.48:

Staurolite \Stau"ro*lite\ (st[add]"r[-o]*l[imac]t), n. [Gr.
   stayro`s a cross + -lite.] (Min.)
   A mineral of a brown to black color occurring in prismatic
   crystals, often twinned so as to form groups resembling a
   cross. It is a silicate of alumina and iron, and is generally
   found imbedded in mica schist. Called also granatite, and
   grenatite.
   [1913 Webster]