Tourmaline

2 definitions found

From The Collaborative International Dictionary of English v.0.48 [gcide]:

  Tourmaline \Tour"ma*line\, n. [F. tourmaline, cf. It. turmalina,
     tormalina, NL. turmalina, turmalinus; all fr. tournamal, a
     name given to this stone in Ceylon.] (Min.)
     A mineral occurring usually in three-sided or six-sided
     prisms terminated by rhombohedral or scalenohedral planes.
     Black tourmaline (schorl) is the most common variety, but


     there are also other varieties, as the blue (indicolite), red
     (rubellite), also green, brown, and white. The red and green
     varieties when transparent are valued as jewels. [Written
     also {turmaline} .]
     [1913 Webster]
  
     Note: Crystals of tourmaline when heated exhibit electric
           polarity (see {Pyroelectric}, n.). Tourmaline is also
           used in the form of a polariscope called tourmaline
           tongs.
           [1913 Webster]

From WordNet (r) 2.0 [wn]:

  tourmaline
       n : a mineral that is a complex borosilicate and hydroxide of
           aluminum containing iron and magnesium and calcium and
           lithium and sodium; it is usually black but occurs in
           transparent colored forms that are used as gemstones