Source : Webster's Revised Unabridged Dictionary (1913)

Garnierite \Gar"ni*er*ite\, n. [Named after the French geologist
   Garnier.] (Min.)
   An amorphous mineral of apple-green color; a hydrous silicate
   of nickel and magnesia. It is an important ore of nickel.

Source : WordNet®

garnierite
     n : a green mineral consisting of hydrated nickel magnesium
         silicate; a source of nickel