Zircon

from WordNet (r) 3.0 (2006)

zircon
    n 1: a common mineral occurring in small crystals; chief source
         of zirconium; used as a refractory when opaque and as a gem
         when transparent [syn: {zircon}, {zirconium silicate}]

from The Collaborative International Dictionary of English v.0.48

Zircon \Zir"con\, n. [F., the same word as jargon. See {Jargon}
   a variety of zircon.]
   1. (Min.) A mineral consisting predominantly of zirconium
      silicate ({Zr2SiO4}) 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}.
      [1913 Webster +PJC]

   2. an imitation gemstone made of {cubic zirconia}.
      [PJC]

   {Zircon syenite}, a coarse-grained syenite containing zircon
      crystals and often also elaeolite. It is largely developed
      in Southern Norway.
      [1913 Webster]