axinite

from The Collaborative International Dictionary of English v.0.48

Axinite \Ax"i*nite\, n. [Named in allusion to the form of the
   crystals, fr. Gr. ? an ax.] (Min.)
   A borosilicate of alumina, iron, and lime, commonly found in
   glassy, brown crystals with acute edges.
   [1913 Webster]