Source : Webster's Revised Unabridged Dictionary (1913)

Aventurine \A*ven"tu*rine\, n. [F. aventurine: cf. It.
   avventurino.]
   1. A kind of glass, containing gold-colored spangles. It was
      produced in the first place by the accidental (par
      aventure) dropping of some brass filings into a pot of
      melted glass.

   2. (Min.) A variety of translucent quartz, spangled
      throughout with scales of yellow mica.

   {Aventurine feldspar}, a variety of oligoclase with internal
      firelike reflections due to the presence of minute
      crystals, probably of hematite; sunstone.