tourmaline

Definitions of tourmaline
  1. noun
    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
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    types:
    schorl
    black tourmaline
    type of:
    mineral
    solid homogeneous inorganic substances occurring in nature having a definite chemical composition
    transparent gem
    a gemstone having the property of transmitting light without serious diffusion
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