Verdelite

Verdelite is probably one of the most common and used gemstones available in the market today. The mineral is dark green in color, though it is sometimes seen in a light green or light brown shade.
General Information
A variety or type of:Tourmaline
Other Names/Trade Names:
Chemical Formula
Na(Li
 
1.5
Al
 
1.5
)Al
 
6
(Si
 
6
O
 
18
)(BO
 
3
)
 
3
(OH)
 
3
(OH)
Gemdat.org, Management Team (2012) Formula given for elbaite. Most, but not all, verdelite is elbaite.
Verdelite Treatments
Routinely heat-treated to lighten the color - Blue Chart Gem Identification, Herve Nicolas Lazzarelli, 2010, p 5
Physical Properties of Verdelite
Mohs Hardness7 to 7.5
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
Specific Gravity2.90 to 3.40
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
TenacityBrittle
Michael O’Donoghue, Gems, Sixth Edition (2006)
Cleavage QualityIndistinct
Walter Schumann, Gemstones of the world (2001)
FractureSub-Conchoidal
Arthur Thomas, Gemstones (2009)
Optical Properties of Verdelite
Refractive Index1.614 to 1.666
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
Optical CharacterUniaxial/-
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
Birefringence0.014 to 0.040
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
PleochroismStrong: dark green - yellow-green
Walter Schumann, Gemstones of the world (2001)
Dispersion0.017
Walter Schumann, Gemstones of the world (2001)
Colour
Colour (General)Green
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
TransparencyTransparent,Translucent,Opaque
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
LustreVitreous
Arthur Thomas, Gemstones (2009)
Crystallography of Verdelite
Crystal SystemTrigonal
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
HabitPrismatic to acicular crystals
Michael O’Donoghue, Gems, Sixth Edition (2006)
Further Information
Mineral information:Verdelite information at mindat.org
Significant Gem Localities
Afghanistan
 
  • Nuristan
    • Kamdesh District
Glas (2002)
Brazil
 
  • Minas Gerais
    • Coronel Murta
      • Barra do Salinas
Cassedanne and Roditi (1996)
Menezes (2009)
Mozambique
 
  • Zambezia Province
    • Alto Ligonha District
Henn and Bank (1997)
Henn and Bank (1997)
Schafer and Arlt (2000)
Sri Lanka
 
  • Sabaragamuwa Province
    • Ratnapura District
      • Ratnapura
Tajikistan
 
  • Gorno-Badakhshan
    • Rangkul' Highlands
Skrigitil (1996)
USA
 
  • California
    • San Diego Co.
      • Pala District
        • Pala
          • Tourmaline Queen Mountain (Pala Mtn; Queen Mtn)
Fisher et al. (1999)
      • Warner Springs District
        • Warner Springs
Laurs (2001, 2002, 2004)
  • Maine
    • Oxford Co.
      • Newry
Freeman (2005)
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