Source : Webster's Revised Unabridged Dictionary (1913)

Zircon \Zir"con\, n. [F., the same word as jargon. See {Jargon}
   a variety of zircon.] (Min.)
   A mineral occurring in tetragonal crystals, usually of a
   brown or gray color. It consists of silica and zirconia. A
   red variety, used as a gem, is called {hyacinth}. Colorless,
   pale-yellow or smoky-brown varieties from Ceylon are called
   {jargon}.

Source : WordNet®

zircon
     n : a common mineral occurring in small crystals; chief source
         of zirconium; used as a refractory when opaque and as a
         gem when transparent [syn: {zirconium silicate}]