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Noun: tourmaline  'tûr-mu,leen or 'tûr-mu-lin [N. Amer], 'tor-mu,leen or 'tûr-mu,leen [Brit]
  1. A mineral that is a complex borosilicate and hydroxide of aluminium containing iron and magnesium and calcium and lithium and sodium; it is usually black but occurs in transparent coloured forms that are used as gemstones

Derived forms: tourmalines

Type of: mineral, transparent gem

Encyclopedia: Tourmaline