Difference between revisions of "Tourmaline"

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[[File:2002.404-SC73200.jpg|thumb|]]
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[[File:2002.404-SC73200.jpg|thumb|Tourmalines aside topaz<br>2002.404]]
 
== Description ==
 
== Description ==
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[[File:2002.405-SC73201.jpg|thumb|Green tourmaline ring<br>2002.404]]
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A semiprecious [[gemstone|gemstone]] composed of an aluminum borosilicate mineral. Tourmaline occurs in pegmatite deposits, such as found in the Ural Mountains, Bohemia, Germany (Saxony), India, the island of Elba, Norway, England, Greenland, Brazil, Madagascar, and the U.S. (New England, New York, New Jersey, Pennsylvania, California). Tourmalines can be opaque or transparent and range in color from black, dark blue (indicolite), light blue (Brazilian sapphire), brown (dravite), green (Brazilian emerald), red (rubellite), red/green parti-colored (watermelon) and, though rare, colorless (achroite). Opaque black tourmalines, called schorl, are the most common. Tourmalines form [[static%20electricity|static electricity]] when they are rubbed or heated. This property makes them useful in pressure gauges, oscillator plates, and other electrical equipment.
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[[File:tourmalinedw.jpg|thumb|Tourmaline (elbaite) crystal]]
  
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A semiprecious [http://cameo.mfa.org/materials/fullrecord.asp?name=gemstone gemstone] composed of an aluminum borosilicate mineral. Tourmaline occurs in pegmatite deposits, such as found in the Ural Mountains, Bohemia, Germany (Saxony), India, the island of Elba, Norway, England, Greenland, Brazil, Madagascar, and the U.S. (New England, New York, New Jersey, Pennsylvania, California). Tourmalines can be opaque or transparent and range in color from black, dark blue (indicolite), light blue (Brazilian sapphire), brown (dravite), green (Brazilian emerald), red (rubellite) and, though rare, colorless (achroite). Opaque black tourmalines, called schorl, are the most common. Tourmalines form [http://cameo.mfa.org/materials/fullrecord.asp?name=static%20electricity static electricity] when they are rubbed or heated. This property makes them useful in pressure gauges, oscillator plates, and other electrical equipment.
 
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[[File:2002.405-SC73201.jpg|thumb|]]
 
 
== Synonyms and Related Terms ==
 
== Synonyms and Related Terms ==
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schorl (opaque black); tourmalin; turmaline; elbaite; indicolite (blue); rubellite (pink or red); dravite (brown); achroite (colorless); Brazilian sapphire (light blue); Brazilian emerald (green); Turmalin (Deut, Pol.); turmalina (Esp., Port.); tourmaline (Fr.); toermalijn (Ned.)
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[[[SliderGallery rightalign|Tourmaline IR-ATR RRUFF R080010.png~IR-ATR (RRUFF)|Tourmaline Raman RRUFF R080010.png~Raman (RRUFF)|tourmalineRS.jpg~Raman (RASMIN)|TourmalineRubelliteitaly2.jpg~Raman (U of Parma)]]]
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== Risks ==
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* Tourmaline is piezoelectric (develops a charge when heated) and may attract dust when displayed under a hot light.
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== Physical and Chemical Properties ==
  
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schorl (opaque black); tourmalin; turmaline; indicolite (blue); rubellite (pink or red); dravite (brown); achroite (colorless); Brazilian sapphire (light blue); Brazilian emerald (green); Turmalin (Deut, Pol.); turmalina (Esp., Port.); tourmaline (Fr.); toermalijn (Ned.)
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* Trigonal system with small, often rounded, hexagonal crystalline prisms, plates or wedges   
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* Cleavage = indistinct
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[[[SliderGallery rightalign|tourmalineRS.jpg~Raman|TourmalineRubelliteitaly2.jpg~Raman]]]
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* Fracture = conchoidal to uneven     
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* Luster = vitreous to resinous   
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== Other Properties ==
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* Streak = white  
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* Fluorescence = variable; some pink stones may show weak red in LW and SW
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Hexagonal system with small, often rounded, hesgonal crystalline prisms, plates or wedges.    
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* Pleochroism = dichroic: medium to strong; usually two tones of gem color
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* Inclusions = thread-like liquid and gas inclusions; mirror-like gas-filled fractures
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Tourmaline is pleochroic, some forms are dichroic.  Fracture = conchoidal or uneven.    
 
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Luster = vitreous to resinous. Streak = white Birefringence = high
 
  
 
{| class="wikitable"
 
{| class="wikitable"
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|-
 
|-
 
! scope="row"| Density
 
! scope="row"| Density
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| 2.9-3.2
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| 2.9-3.2 g/ml
 
|-
 
|-
 
! scope="row"| Refractive Index
 
! scope="row"| Refractive Index
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| 1.63; 1.66
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| 1.624 - 1.650
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|-
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! scope="row"| Birefringence
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| 0.018 - 0.020
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|-
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! scope="row"| Dispersion
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| 0.017
 
|}
 
|}
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== Hazards and Safety ==
 
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Tourmaline is piezoelectric (develops a charge when heated) and may attract dust when displayed under a hot light.
 
  
 
== Comparisons ==
 
== Comparisons ==
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[[media:download_file_444.pdf|Natural and Simulated Diamonds]]
 
[[media:download_file_444.pdf|Natural and Simulated Diamonds]]
  
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==Resources and Citations==
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* Gem Identification Lab Manual, Gemological Institute of America, 2016.
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== Additional Images ==
 
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<gallery>
 
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File:tourmalinedw.jpg|Tourmaline (elbaite) crystal
 
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</gallery>
 
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== Sources Checked for Data in Record ==
 
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* Jack Odgen, ''Jewellery of the Ancient World'', Rizzoli International Publications Inc., New York City, 1982
 
* Jack Odgen, ''Jewellery of the Ancient World'', Rizzoli International Publications Inc., New York City, 1982
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* R.F.Symmes, T.T.Harding, Paul Taylor, ''Rocks, Fossils and Gems'', DK Publishing, Inc., New York City, 1997
 
* R.F.Symmes, T.T.Harding, Paul Taylor, ''Rocks, Fossils and Gems'', DK Publishing, Inc., New York City, 1997
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* ''Encyclopedia Britannica'', http://www.britannica.com  Comment: "tourmaline" [Accessed December 4, 2001]. (tech info)..
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* ''Encyclopedia Britannica'', http://www.britannica.com  Comment: "tourmaline" Encyclopædia Britannica    [Accessed December 4, 2001]. (tech info)..
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* Website: http://www.geo.utexas.edu/courses/347k/redesign/gem_notes/Tourmaline/tourm_triple_page.htm
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* Website address 1  Comment: http://www.geo.utexas.edu/courses/347k/redesign/gem_notes/Tourmaline/tourm_triple_page.htm
 
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* C.W.Chesterman, K.E.Lowe, ''Audubon Society Field Guide to North American Rocks and Minerals'', Alfred A. Knopf, New York, 1979
 
* C.W.Chesterman, K.E.Lowe, ''Audubon Society Field Guide to North American Rocks and Minerals'', Alfred A. Knopf, New York, 1979
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* Wikipedia: [https://en.wikipedia.org/wiki/Tourmaline Tourmaline] (Accessed Sept. 17, 2005 and Dec 2022)
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* Wikipedia, the free encyclopedia, at http://www.wikipedia.com  Comment: http://en.wikipedia.org/wiki/Tourmaline (Accessed Sept. 17, 2005)
 
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* G.S.Brady, ''Materials Handbook'', McGraw-Hill Book Co., New York, 1971  Comment: p. 435
 
* G.S.Brady, ''Materials Handbook'', McGraw-Hill Book Co., New York, 1971  Comment: p. 435
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* Richard S. Lewis, ''Hawley's Condensed Chemical Dictionary'', Van Nostrand Reinhold, New York, 10th ed., 1993
 
* Richard S. Lewis, ''Hawley's Condensed Chemical Dictionary'', Van Nostrand Reinhold, New York, 10th ed., 1993
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* ''Van Nostrand's Scientific Encyclopedia'', Douglas M. Considine (ed.), Van Nostrand Reinhold, New York, 1976
 
* ''Van Nostrand's Scientific Encyclopedia'', Douglas M. Considine (ed.), Van Nostrand Reinhold, New York, 1976
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* Random House, ''Webster's Encyclopedic Unabridged Dictionary of the English Language'', Grammercy Book, New York, 1997
 
* Random House, ''Webster's Encyclopedic Unabridged Dictionary of the English Language'', Grammercy Book, New York, 1997
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* ''The American Heritage Dictionary'' or ''Encarta'', via Microsoft Bookshelf 98, Microsoft Corp., 1998
 
* ''The American Heritage Dictionary'' or ''Encarta'', via Microsoft Bookshelf 98, Microsoft Corp., 1998
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* ''CRC Handbook of Chemistry and Physics'', Robert Weast (ed.), CRC Press, Boca Raton, Florida, v. 61, 1980  Comment: density=3.0-3.2
 
* ''CRC Handbook of Chemistry and Physics'', Robert Weast (ed.), CRC Press, Boca Raton, Florida, v. 61, 1980  Comment: density=3.0-3.2
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[[Category:Materials database]]
 
[[Category:Materials database]]

Latest revision as of 12:27, 4 January 2023

Tourmalines aside topaz
2002.404

Description

Green tourmaline ring
2002.404

A semiprecious Gemstone composed of an aluminum borosilicate mineral. Tourmaline occurs in pegmatite deposits, such as found in the Ural Mountains, Bohemia, Germany (Saxony), India, the island of Elba, Norway, England, Greenland, Brazil, Madagascar, and the U.S. (New England, New York, New Jersey, Pennsylvania, California). Tourmalines can be opaque or transparent and range in color from black, dark blue (indicolite), light blue (Brazilian sapphire), brown (dravite), green (Brazilian emerald), red (rubellite), red/green parti-colored (watermelon) and, though rare, colorless (achroite). Opaque black tourmalines, called schorl, are the most common. Tourmalines form Static electricity when they are rubbed or heated. This property makes them useful in pressure gauges, oscillator plates, and other electrical equipment.

Tourmaline (elbaite) crystal

Synonyms and Related Terms

schorl (opaque black); tourmalin; turmaline; elbaite; indicolite (blue); rubellite (pink or red); dravite (brown); achroite (colorless); Brazilian sapphire (light blue); Brazilian emerald (green); Turmalin (Deut, Pol.); turmalina (Esp., Port.); tourmaline (Fr.); toermalijn (Ned.)

IR-ATR (RRUFF)

Tourmaline IR-ATR RRUFF R080010.png

Raman (RRUFF)

Tourmaline Raman RRUFF R080010.png

Raman (RASMIN)

TourmalineRS.jpg

Raman (U of Parma)

TourmalineRubelliteitaly2.jpg

Risks

  • Tourmaline is piezoelectric (develops a charge when heated) and may attract dust when displayed under a hot light.

Physical and Chemical Properties

  • Trigonal system with small, often rounded, hexagonal crystalline prisms, plates or wedges
  • Cleavage = indistinct
  • Fracture = conchoidal to uneven
  • Luster = vitreous to resinous
  • Streak = white
  • Fluorescence = variable; some pink stones may show weak red in LW and SW
  • Pleochroism = dichroic: medium to strong; usually two tones of gem color
  • Inclusions = thread-like liquid and gas inclusions; mirror-like gas-filled fractures
Composition (Na,Ca)(Al,Fe)B3Al3(AlSi2O9)(O,OH,F)4
Mohs Hardness 7.0 - 7.5
Density 2.9-3.2 g/ml
Refractive Index 1.624 - 1.650
Birefringence 0.018 - 0.020
Dispersion 0.017

Comparisons

Properties of Common Gemstones

Natural and Simulated Diamonds

Resources and Citations

  • Gem Identification Lab Manual, Gemological Institute of America, 2016.
  • Jack Odgen, Jewellery of the Ancient World, Rizzoli International Publications Inc., New York City, 1982
  • R.F.Symmes, T.T.Harding, Paul Taylor, Rocks, Fossils and Gems, DK Publishing, Inc., New York City, 1997
  • Encyclopedia Britannica, http://www.britannica.com Comment: "tourmaline" [Accessed December 4, 2001]. (tech info)..
  • Website: http://www.geo.utexas.edu/courses/347k/redesign/gem_notes/Tourmaline/tourm_triple_page.htm
  • C.W.Chesterman, K.E.Lowe, Audubon Society Field Guide to North American Rocks and Minerals, Alfred A. Knopf, New York, 1979
  • Wikipedia: Tourmaline (Accessed Sept. 17, 2005 and Dec 2022)
  • G.S.Brady, Materials Handbook, McGraw-Hill Book Co., New York, 1971 Comment: p. 435
  • Richard S. Lewis, Hawley's Condensed Chemical Dictionary, Van Nostrand Reinhold, New York, 10th ed., 1993
  • Van Nostrand's Scientific Encyclopedia, Douglas M. Considine (ed.), Van Nostrand Reinhold, New York, 1976
  • Random House, Webster's Encyclopedic Unabridged Dictionary of the English Language, Grammercy Book, New York, 1997
  • The American Heritage Dictionary or Encarta, via Microsoft Bookshelf 98, Microsoft Corp., 1998
  • CRC Handbook of Chemistry and Physics, Robert Weast (ed.), CRC Press, Boca Raton, Florida, v. 61, 1980 Comment: density=3.0-3.2

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