Source : Webster's Revised Unabridged Dictionary (1913)

Siliceous \Si*li"ceous\, a. [L. siliceus, fr. silex, silicis, a
   flint.]
   Of or pertaining to silica; containing silica, or partaking
   of its nature. [Written also {silisious}.]

Source : WordNet®

siliceous
     adj : relating to or containing or resembling silica; "gritrock is
           siliceous sandstone" [syn: {silicious}]