Difference between revisions of "Tourmaline"

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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.)
 
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.)
 
[[File:tourmalinedw.jpg|thumb|Tourmaline (elbaite) crystal]]
 
[[File:tourmalinedw.jpg|thumb|Tourmaline (elbaite) crystal]]
−
[[[SliderGallery rightalign|tourmalineRS.jpg~Raman|TourmalineRubelliteitaly2.jpg~Raman]]]
+
[[[SliderGallery rightalign|tourmalineRS.jpg~Raman (RASMIN)|TourmalineRubelliteitaly2.jpg~Raman (U of Parma)]]]
  
 
== Risks ==
 
== Risks ==
−
 
+
* Tourmaline is piezoelectric (develops a charge when heated) and may attract dust when displayed under a hot light.
−
Tourmaline is piezoelectric (develops a charge when heated) and may attract dust when displayed under a hot light.
 
 
== Physical and Chemical Properties ==
 
== Physical and Chemical Properties ==
  
−
* Hexagonal system with small, often rounded, hexgonal crystalline prisms, plates or wedges.    
+
* Hexagonal system with small, often rounded, hexagonal crystalline prisms, plates or wedges   
−
* Tourmaline is pleochroic, some forms are dichroic.  
+
* Tourmaline is pleochroic, some forms are dichroic   
−
* Fracture = conchoidal or uneven.    
+
* Fracture = conchoidal or uneven     
−
* Luster = vitreous to resinous.  
+
* Luster = vitreous to resinous   
 
* Streak = white   
 
* Streak = white   
−
* Birefringence = high
+
* Pleochroism = medium to strong; usually two tones of gem color
 +
* Fluorescence = variable; some pink stones may show weak red in LW and SW
  
 
{| class="wikitable"
 
{| class="wikitable"
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! scope="row"| Refractive Index
 
! scope="row"| Refractive Index
 
| 1.63; 1.66
 
| 1.63; 1.66
 +
|-
 +
! scope="row"| Birefringence
 +
| 0.018 - 0.20
 +
 
|}
 
|}
  
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==Resources and Citations==
 
==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
 
* 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
 
* 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)..
 
* ''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
 
* 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
 
* C.W.Chesterman, K.E.Lowe, ''Audubon Society Field Guide to North American Rocks and Minerals'', Alfred A. Knopf, New York, 1979
−
 
 
* Wikipedia: http://en.wikipedia.org/wiki/Tourmaline (Accessed Sept. 17, 2005)
 
* Wikipedia: http://en.wikipedia.org/wiki/Tourmaline (Accessed Sept. 17, 2005)
−
 
 
* 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
−
 
 
* 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
−
 
 
* ''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
−
 
 
* 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
−
 
 
* ''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
−
 
 
* ''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
−
 
  
  
 
[[Category:Materials database]]
 
[[Category:Materials database]]

Revision as of 12:35, 12 December 2022

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) 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.

Synonyms and Related Terms

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.)

Tourmaline (elbaite) crystal

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

  • Hexagonal system with small, often rounded, hexagonal crystalline prisms, plates or wedges
  • Tourmaline is pleochroic, some forms are dichroic
  • Fracture = conchoidal or uneven
  • Luster = vitreous to resinous
  • Streak = white
  • Pleochroism = medium to strong; usually two tones of gem color
  • Fluorescence = variable; some pink stones may show weak red in LW and SW
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 1.63; 1.66
Birefringence 0.018 - 0.20

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: http://en.wikipedia.org/wiki/Tourmaline (Accessed Sept. 17, 2005)
  • 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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