Cyanite

from WordNet (r) 3.0 (2006)

cyanite
    n 1: a grey or greenish-blue mineral consisting of aluminum
         silicate in crystalline form; occurs in metaphoric rock,
         used as a refractory [syn: {kyanite}, {cyanite}]

from The Collaborative International Dictionary of English v.0.48

Cyanite \Cy"a*nite\ (-n?t), n. [See {Cyanic}.] (Min.)
   A mineral occuring in thin-bladed crystals and crystalline
   aggregates, of a sky-blue color. It is a silicate of
   aluminium. [Written also {kyanite}.]
   [1913 Webster] cyanobacterium