Minerals & Crystals Codexery

Tourmaline

A boron silicate mineral group with many colors and uses.

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Tourmaline is a group of silicate minerals with one of the most complicated chemical compositions among silicates.[1] The Sinhalese term tōramalli, which originally designated carnelian, is the source of the name "tourmaline".[2][3] Schorl, the sodium iron endmember of the tourmaline group, is the most common species and is estimated to constitute 95% or more of all natural tourmaline.[4]

Key facts and history

The name "schorl" was in use prior to 1400, as a village now known as Zschorlau in Saxony was then named "Schorl" and had a tin mine producing black tourmaline.[4] Johannes Mathesius first described schorl with the name "schürl" in 1562.[4] In 1884, Gustav Tschermak first used the name dravite for magnesium-rich tourmaline from the Drava river area.[5] A lithium-tourmaline elbaite was one of three minerals in which lithium was first determined in 1818 by Johan August Arfwedson.[6]

The Dutch East India Company transported large numbers of vividly colored Ceylonese tourmaline gems to Europe.[7] Because its pyroelectric nature allowed it to draw in and then push away hot ashes, tourmaline was occasionally referred to as the "Ceylonese Magnet".[7] The first identification of fluorine within tourmaline was made by Karl Friedrich August Rammelsberg in 1850.[8] Vladimir Vernadsky suggested the name elbaite in 1914 for a tourmaline from Elba Island that is rich in lithium, sodium, and aluminum.[8]

What the research sources say

The GIA also states that some pink and yellow tourmalines may owe their hues to color centers caused by radiation.[9] According to the GIA, tourmaline becomes electrically charged when heated.[9] The minerals.net account lists chrome tourmaline as a deep green variety caused by chromium impurities.[10] The same source notes that the gem trade now uses "Paraiba Tourmaline" to describe any light to neon blue tourmaline from any worldwide location.[10]

The nationaljeweler.com article reports that in October 1972, four men unearthed a huge source of tourmaline crystals at the Dunton Mine in Newry, Maine, producing more than a ton of gem tourmaline.[11] According to the GIA, tourmaline's crystal system is trigonal, and it is the only common mineral exhibiting three-sided prisms.[9] That same article reports that the 1972 find at the Dunton Mine yielded green, red, and watermelon tourmaline.[11]

References

  1. Wikipedia, "Tourmaline" (CC BY-SA 4.0), which cites: Hawthorne, F.C. & Henry, D.J. (1999). "Classification of the minerals of the tourmaline group" . European Journal of Mineralogy, 11, pp. 201–215. (original not read by us) en.wikipedia.org
  2. Wikipedia, "Tourmaline" (CC BY-SA 4.0), which cites: "tourmaline", Oxford Dictionaries (original not read by us) en.wikipedia.org
  3. Wikipedia, "Tourmaline" (CC BY-SA 4.0), which cites: "Tourmaline - Etymology, Origin & Meaning", etymonline (original not read by us) en.wikipedia.org
  4. Wikipedia, "Tourmaline" (CC BY-SA 4.0), which cites: Ertl, 2006. (original not read by us) en.wikipedia.org
  5. Wikipedia, "Tourmaline" (CC BY-SA 4.0), which cites: Ertl, 2007. (original not read by us) en.wikipedia.org
  6. Wikipedia, "Tourmaline" (CC BY-SA 4.0), which cites: Ertl, 2008. (original not read by us) en.wikipedia.org
  7. Wikipedia, "Tourmaline" (CC BY-SA 4.0), which cites: Erhart, "Fundamentals of Piezoelectric Sensorics: Mechanical, Dielectric, and Thermodynamical Properties of Piezoelectric Materials", Springer, 2010, p. 4 (original not read by us) en.wikipedia.org
  8. Wikipedia, "Tourmaline" (CC BY-SA 4.0), which cites: Ertl, 2008.; Ertl, 2008.; Ertl, 2008. (original not read by us) en.wikipedia.org
  9. "What is Tourmaline? – GIA". facts only, no text reused. gia.edu
  10. "Tourmaline: The gemstone Tourmaline information and pictures", minerals.net. facts only, no text reused. minerals.net
  11. "Maine Museum Ready to Reveal Jewelry Designs Set with Historic Tourmalines", nationaljeweler.com. facts only, no text reused. nationaljeweler.com

Each numbered sentence above was checked against the source it cites before publication. Sentences citing Wikipedia adapt text from the English Wikipedia article Tourmaline (contributors), used under CC BY-SA 4.0; this entry is available under the same licence. Other sources were used for facts only; no text or images are copied from them.

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Tourmaline · Gemstones

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Sources

Compiled from Wikipedia and the sources listed below. Text from Wikipedia is available under CC BY-SA 4.0; this entry is adapted from it.

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