Tourmaline

Tourmaline is a gorgeous gemstone which occurs in a wide range of colours – reds, pinks, greens, blue, black, even mixed colours and multiple colours in one crystal. It is regarded as semi-precious, and higher end pieces are used to make jewellery.

It displays an interesting crystalline form, which makes ‘rough’ specimens popular with collectors. With the wide array of colours available, it would be quite easy to form a collection comprised purely of Tourmaline!

Tourmaline can be quite expensive – especially the higher-grade pieces, and any specimens with multiple colours in a single crystal. One of my favourite variations is known as ‘Watermelon Tourmaline’ and is a mixture of pinks and greens.

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Appearance, Uses and History

Tourmaline is pretty much exclusively used as a gemstone and is both one of the best loved and most recognised. The name refers to an informal group of boron silicate minerals, which all have inclusions or traces of various other elements causing colours.

The name allegedly derives from a Tamil word, ‘thoramalli’, which refers to a group of gemstones found in the Indian subcontinent.

Gem quality Tourmaline comes from a few locations worldwide, with a lot of the mining being done in Brazil, Africa, and the USA.

 

Locales

Tourmaline occurs all around the world, although there are some locations with particularly gemmy specimens that collectors will be interested in.

Excellent quality crystals can be found in Afghanistan, Australia, Austria, Brazil, Bulgaria, Canada, China, Czechia, the Congo, Finland, India, Kazakhstan, Kenya, Madagascar, Mozambique, Myanmar, Namibia, Nepal, Nigeria, Pakistan, Russia, Spain, Tanzania, the USA, Vietnam, and Zimbabwe.

Mineralogy

Chemistry
Tourmaline is a widely variable group of minerals with varying chemical compositions. However, it is a boron silicate at heart.
Colours and Variations

Tourmaline can occur in clear, blue, red, green, yellow, orange, brown, pink, purple, black, multicoloured – honestly, the most colourful gemstone there is.

  • Achroite is a relatively rare colourless form of Tourmaline.
  • Cats Eye Tourmaline is any form of Tourmaline with the ‘cats eye’ optical effect, a form of chatoyancy.
  • Chrome Tourmaline (or Chrome Dravite) is a form of Tourmaline which gains its colour from traces of Chromium.
  • Dravite is often known as the ‘brown Tourmaline’, although it does occur in green and green-brown too. It is very difficult to distinguish from Uvite.
  • Elbaite is the most widely used form of gem Tourmaline, and occurs in a huge number of colours. It is often bicolour or multicoloured.
  • Indicolite is a variety of blue Tourmaline.
  • Paraiba Tourmaline is a neon blue to neon blue-green form, and incredibly prized!
  • Rubellite is a pink to red variant, very popular with jewellers.
  • Schorl is the most common form of Tourmaline, a lustrous black mineral. It is not often used for jewellery, but is prized by collectors, especially when combined with other minerals.
  • Uvite is a rare green to green-brown ariety of Tourmaline. It is very difficult to distinguish from Dravite.
  • Watermelon Tourmaline is a multicoloured Tourmaline with a pink centre surrounded by a green layer, resembling a cut slice of watermelon.
Streak
White
Luster
Vitreous
Fracture
Uneven, conchoidal, brittle.
Transparency
Transparent to opaque
Crystal habit
Parallel and elongated. Acicular or radiating prisms. Massive. Sometimes grains.
Mohs hardness
7.0 – 7.5
Specific Gravity
2.9 – 3.3
Fluorescence
Pink Tourmaline may have mild fluorescence.
Easiest testing method
Common Treatments
Heat treatment and irradiation are relatively common. Irradiation is very hard to detect.

Hazards and Warnings

Almost all rocks, minerals (and, frankly, almost all other substances on earth) can produce toxic dust when cutting, which can cause serious respiratory conditions including silicosis.

When cutting or polishing rocks, minerals, shells, etc, all work should be done wet to minimise the dust, and a suitable respirator or extraction system should be used.

Translations

Arabic:

  • التورمالين

Hindi:

  • टूमलाइन

Portuguese:

  • turmalina

Bengali:

  • টুম্যালিন্

Indonesian:

  • turmalin

Punjabi:

English:

  • tourmaline

Italian:

  • tormalina

Russian:

  • турмалин

French:

Japanese:

  • トルマリン

Spanish:

  • turmalina

German:

  • Turmalin

Korean:

  • 전기석

Thai:

  • ทัวร์มาลีน

Gujurati:

  • ટૂરમાલાઇન

Mandarin and Traditional Chinese:

  • 电气石
  • 電氣石

Urdu:

  • ٹور لائن

Further Reading / External Links