Tourmaline

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Tourmaline is a complex borosilicate mineral group renowned for the widest color range of any gem species, spanning colorless and black to every hue of the spectrum, and often displaying several colors within a single crystal—as in the pink-and-green Watermelon Tourmaline. Major sources include Brazil, Nigeria, Afghanistan, Madagascar, and the United States, each producing distinctive and prized varieties. A Mohs hardness of 7 to 7.5 makes tourmaline durable enough for regular wear, and its versatility has made it one of the world's most popular gems. It shares the role of October birthstone with opal. The mineral crystallizes in the trigonal system and is strongly pyroelectric and piezoelectric, developing an electric charge when heated or placed under pressure—a property first noted by eighteenth-century Dutch traders.

Physical & Optical Properties

Category Semi-Precious Gems

Mohs Hardness 7.0 – 7.5

Specific Gravity 2.85 – 3.35

Refractive Index 1.614 – 1.666

Crystal System Trigonal

Luster Vitreous

Cleavage Poor

Fracture Sub-Conchoidal

Color various

Birefringence 0.014

Dispersion 0.017

Pleochroism Pink tourmaline - distinct: colorless-pink - pinkish-red; Orange/brown tourmaline - strong: yellowish-brown - dark(greenish)-brown; Yellow tourmaline - distinct: pale yellow - dark yellow; Violet/purple tourmaline - strong: light purple - purple; Blue - strong: light blue - dark blue; Green - strong: yellow-green - dark green

Mohs Hardness

Mohs hardness of Tourmaline shown against the ten reference minerals, from talc (1) to diamond (10).

Mohs	Reference mineral	Tourmaline
1	Talc
2	Gypsum
3	Calcite
4	Fluorite
5	Apatite
6	Orthoclase
7	Quartz	●
8	Topaz
9	Corundum
10	Diamond

Crystal System

Value & Market

Price Tier Moderate ($50-500/ct)

Where to Buy Tourmaline

Blue Nile Fine jewelry retailer

James Allen Gemstone jewelry

Brilliant Earth Ethically sourced gems

Amazon Wide selection

Links may earn a commission at no extra cost to you.

Cultural Significance

Birthstone Month 10 (traditional)

Treatments

Synthetic tourmalines are used only for research purposes. The stones, offered as synthetic tourmaline, are rarely tourmaline-colored synthetic spinels. - Gemstones of the world, Walter Schumann, 2001, p 112 7 to 7.5Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) More from other references 2.85 to 3.35Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) More from other references BrittleMichael O?Donoghue, Gems, Sixth Edition (2006) PoorMichael O?Donoghue, Gems, Sixth Edition (2006) Very poorMore from other references Sub-ConchoidalArthur Thomas, Gemstones (2009) 1.614 to 1.666Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) More from other references Uniaxial/-Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) More from other references 0.014 to 0.040Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) More from other references Pink tourmaline - distinct: colorless-pink - pinkish-red; Orange/brown tourmaline - strong: yellowish-brown - dark(greenish)-brown; Yellow tourmaline - distinct: pale yellow - dark yellow; Violet/purple tourmaline - strong: light purple - purple; Blue - strong: light blue - dark blue; Green - strong: yellow-green - dark greenHerve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) More from other references 0.017Arthur Thomas, Gemstones (2009) Tourmaline cat's eyes exist in various colors, but only in the green and pink varieties. Chatoyancy is usually strong, caused by thin tube-like inclusions. Some tourmalines show a slight change of color in artificial light. They have a vitreous sheen ob crystal surfaces, a greasy sheen on fractured surfaces.Walter Schumann, Gemstones of the world (2001) More from other references Multi-colored crystals are commonHerve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) More from other references Transparent,Translucent,OpaqueUlrich Henn and Claudio C. Milisenda, Gemmological Tables (2004) More from other references VitreousArthur Thomas, Gemstones (2009) Mostly inertHerve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) TrigonalHerve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) More from other references Prismatic to acicular crystalsMichael O?Donoghue, Gems, Sixth Edition (2006) More from other references Tourmaline information at mindat.org Afghanistan  Glas (2002) Garnier, V., Giuliani, G., Ohnenstetter, D., Fallick, A.E., Dubessy, J., Banks, D., Vinh, H.Q., Lhomme, T., Maluski, H., Pêcher, A., Bakhsh, K.A., Long, P.V., Trinh, P.T., and Schwarz, D. (2008): Ore Geology Reviews 34, 169-191. [var: Achroite] Bowersox and Chamberlin (1995) [var: Indicolite] Bowersox and Chamberlin (1995) Bowersox and Chamberlin (1995) [var: Indicolite] Glas (2002) E.Ya. Kievlenko, Geology of gems, 2003, p. 110 Glas (2002) Glas (2002) Glas (2002) Bowersox and Chamberlin (1995) Glas (2002) [var: Indicolite] Glas (2002) Bowersox and Chamberlin (1995) Brazil  Cassedanne and Roditi (1996) [var: Elbaite] Kievlenko E.Ya., Geology of gems, 2003, p. 113 Menezes (2009) Steger (1999) [var: Rubellite] Cassedanne and Roditi (1996) [var: Rubellite] Steger (1999) [var: Indicolite] Cassedanne and Roditi (1996) Steger (1999) [var: Elbaite] [var: Indicolite] Cassedanne and Roditi (1996) [var: Indicolite] Cassedanne and Roditi (1996) [var: Rubellite] Bastos (2002) [var: Verdelite] Menezes (2009) Cassedanne and Roditi (1996) [var: Rubellite] Cassedanne and Roditi (1996) [var: Indicolite] Menezes (2009) Cassedanne and Roditi (1996) Kievlenko E.Ya., Geology of gems, 2003, p. 113 [Copper-bearing Elbaite var: Paraíba Tourmaline] Wilson, W. E. (2002): Cuprian elbaite from the Batalha Mine, Paraíba, Brazil. Mineralogical Record, 33: 127-137 Johnson et al. (2000) Johnson et al. (2000) China  Tang et al. (2004) Wu (2004) India  [var: Schorl] Kenya  Simonet (2000, 2006) Collection of NHM, Vienna Simonet (2000) MadagascarE.Ya. Kievlenko, Geology of gems, 2003, p. 110 Pezzotta (2006) [var: Schorl] Madagascar, extraLapis English No.1, 2001, p. 46 [var: Schorl] Madagascar, extraLapis English No.1, 2001, p. 46 Pezzotta (1999) Madagascar - extraLapis English No.1, 2001, p. 64 Pezzotta (2006) Pezzotta (2006) Danet (2006) Milisenda et al. (2001) Madagascar - extraLapis English No.1, p. 92 E.Ya. Kievlenko, Geology of gems, 2003, p. 111 Dirlam at al. (2002) E.Ya. Kievlenko, Geology of gems, 2003, p. 110 Laurs (2000) Danet (2007) [var: Rubellite] Lacroix, A. (1912): Sur quelques minéraux des pegmatites du Vakinankaratra (Madagascar). Bulletin de la Société française de Minéralogie, Paris 35 , 76-84 Dirlam at al. (2002) [var: Schorl] E.Ya. Kievlenko, Geology of gems, 2003, p. 112 Mozambique  mindat.org [var: Elbaite] [var: Indicolite] Henn and Bank (1997) [var: Indicolite] Henn and Bank (1997) [var: Indicolite] Schafer and Arlt (2000) Myanmar  [var: Rubellite] [var: Schorl] Ted Themelis (2008) Gems & mines of Mogok [var: Schorl] Ted Themelis (2008) Gems & mines of Mogok [var: Schorl] Ted Themelis (2008) Gems & mines of Mogok Ted Themelis (2008) Gems & mines of Mogok [var: Schorl] Ted Themelis (2008) Gems & mines of Mogok [var: Schorl] Ted Themelis (2008) Gems & mines of Mogok [var: Schorl] Ted Themelis (2008) Gems & mines of Mogok [var: Schorl] Ted Themelis (2008) Gems & mines of Mogok Ted Themelis (2008) Gems & mines of Mogok [var: Schorl] Ted Themelis (2008) Gems & mines of Mogok [var: Schorl] Ted Themelis (2008) Gems & mines of Mogok [var: Schorl] Ted Themelis (2008) Gems & mines of Mogok [var: Schorl] Ted Themelis (2008) Gems & mines of Mogok [var: Schorl] Ted Themelis (2008) Gems & mines of Mogok [var: Schorl] Ted Themelis (2008) Gems & mines of Mogok [var: Schorl] Ted Themelis (2008) Gems & mines of Mogok Ted Themelis (2008) Gems & mines of Mogok Ted Themelis (2008) Gems & mines of Mogok [var: Dravite] Ted Themelis (2008) Gems & mines of Mogok [var: Elbaite] Ted Themelis (2008) Gems & mines of Mogok Ted Themelis (2008) Gems & mines of Mogok [var: Dravite] Ted Themelis (2008) Gems & mines of Mogok [var: Elbaite] Ted Themelis (2008) Gems & mines of Mogok [var: Schorl] Ted Themelis (2008) Gems & mines of Mogok Ted Themelis (2008) Gems & mines of Mogok [var: Schorl] Ted Themelis (2008) Gems & mines of Mogok [var: Schorl] Ted Themelis (2008) Gems & mines of Mogok Ted Themelis (2008) Gems & mines of Mogok Ted Themelis (2008) Gems & mines of Mogok Ted Themelis (2008) Gems & mines of Mogok [var: Schorl] Ted Themelis (2008) Gems & mines of Mogok [var: Schorl] Ted Themelis (2008) Gems & mines of Mogok Ted Themelis (2008) Gems & mines of Mogok Ted Themelis (2008) Gems & mines of Mogok Ted Themelis (2008) Gems & mines of Mogok [var: Schorl] Ted Themelis (2008) Gems & mines of Mogok Ted Themelis (2008) Gems & mines of Mogok [var: Dravite] Ted Themelis (2008) Gems & mines of Mogok [var: Elbaite] Ted Themelis (2008) Gems & mines of Mogok [var: Schorl] Ted Themelis (2008) Gems & mines of Mogok [var: Rubellite] Kyi et al. (2005) Glas (2002) Namibia  Mossman (2002) [var: Indicolite] Schneider and Seeger (1992) [var: Indicolite] Mossman (2002) [var: Indicolite] Schneider and Seeger (1992) Beard (1999) Nepal  Bassett (1987) Koivula et al. (1994) Bassett (1987) Nigeria  Henn (2001) Pakistan  Laurs et al. (1998) E.Ya.Kievlenko, Geology of gems, 2003, p. 110 Laurs et al. (1998) Glas (2002) [var: Indicolite] Laurs et al. (1998) Glas (2002) Russia  Smith and Smith (1995) [var: Rubellite] Godovikov and Bulgak (1993) [var: Rubellite] Godovikov and Bulgak (1993) [var: Rubellite] Godovikov and Bulgak (1993) Sri Lanka  Milisenda and Henn (1999) Milisenda and Henn (1999) [var: Achroite] Tajikistan  Skrigitil (1996) Skrigitil (1996) Tanzania  http://www.ganoksin.com/borisat/nenam/tanzania-mines.htm [var: Chrome-Tourmaline] Dirlam at al. (1992) gemexplorer.org USA  [var: Elbaite] Min.Rec.:20(5):399. / Foord, E.E. (1977): Famous mineral localities. The Himalaya Dike System. Mineralogical Record 8, 461-475 Morgan and London (1999) [var: Indicolite] Fisher et al. (1999) [var: Elbaite] Fisher, J. 2002. Gem and rare-element pegmatites of southern California. Mineralogical Record, Vol. 33: pages 378-381. Morgan and London (1999) [var: Achroite] Laurs (2001, 2002, 2004) [var: Achroite] Freeman (2005) [var: Achroite] Freeman (2005) Vietnam  Pham et al. (2004) Pham et al. (2004) Pham et al. (2004) Zambia  Milisenda et al. (2000) Zimbabwe  Glas (2002)