Tourmaline

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Tourmaline is a large family of minerals composed of a complex boro-silicate. The most common species of the tourmaline group is Elbaite (named after the island of Elba in the Mediterranean) and it occurs in all colors of the rainbow. It was first brought to Europe by Dutch traders whom also discovered its pyro-electric effect. When heated, tourmaline is electrically charged, this charge was used to attract ashes from a smoked pipe and these stones thus received the glorious name of asschentrekker (old Dutch for ash puller).

1950's platinum earrings set with diamonds and rubelitte tourmalines.
Image courtesy of Lang Antiques
Another property which tourmaline is famous for is its ability to totally block color when viewed in a particular direction and it is due to this strong selective absorption property that some darker stones were used as early polarizing filters.

There are many color varieties in the tourmaline group and some have distinctive tradenames:

  • Rubellite - pink to red
  • Verdelite - green
  • Indicolite - blue
  • Achroite - colorless
  • Dravite - brown
  • Schorl - black
  • Watermelon - pink core with a green periphery
  • parti-colored - several colors in one stone

More recently a variety was discovered in the Paraiba state of Brazil which exhibits neon colors. These are also found in the neighboring state Rio Grande do Norte, as well as in Africa.


Gemological information for tourmaline
Color All colors
Crystal Structure Trigonal
Family Tourmaline
Refractive Index 1.624-1.644
Durability Very durable
Hardness 7
Treatments Sometimes heat treated
Tourmaline care
Ultrasonic cleaning Not safe
Steam cleaning Usually safe
Warm soapy water Safe
Chemical attack Stable
Light sensitivity Stable
Heat sensitivity May change color

Online G&G articles on tourmaline

Lang Antiques
Lang Antiques