noun (n)

• a common mineral occurring in small crystals; chief source of zirconium; used as a refractory when opaque and as a gem when transparent(noun.substance)

  Synonym:
  zirconium silicate
  

  source: wordnet30
• 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.(noun)

  source: webster1913