Schorl

Big Photo

Pakistan
1.44 carats
© Brian Kosnar - Mineral Classics

The most common species of tourmaline is schorl. It was named after an old mining expression for "false ore". Schorl is usually bluish or brownish black to black.
General Information
A variety or type of:Tourmaline
Chemical Formula
Na(Fe
2+
3
)Al
 
6
(Si
 
6
O
 
18
)(BO
 
3
)
 
3
(OH)
 
3
(OH)
Gemdat.org, Management Team (2012)
Photos of natural/un-cut material from mindat.org
Physical Properties of Schorl
Mohs Hardness7 to 0
Anthony et al, Handbook of mineralogy (2001)
Specific Gravity3.18 to 3.22
Anthony et al, Handbook of mineralogy (2001)
TenacityBrittle
Anthony et al, Handbook of mineralogy (2001)
Cleavage QualityPoor
Anthony et al, Handbook of mineralogy (2001) Very poor
FractureUneven,Conchoidal
Anthony et al, Handbook of mineralogy (2001)
Optical Properties of Schorl
Refractive Index1.635 to 1.672
Anthony et al, Handbook of mineralogy (2001)
Optical CharacterUniaxial/-
Anthony et al, Handbook of mineralogy (2001) Under strain may show slight biaxiality
Birefringence0.025
Anthony et al, Handbook of mineralogy (2001)
PleochroismVery strong: yellow-brown - pale yellow, pale brown.
Anthony et al, Handbook of mineralogy (2001)
Colour
Colour (General)Black, brownish black, bluish black; in thin section, bluish yellow.
Anthony et al, Handbook of mineralogy (2001)
TransparencyTransparent,Translucent,Opaque
Anthony et al, Handbook of mineralogy (2001) Transparent to nearly opaque
LustreVitreous,Resinous
Anthony et al, Handbook of mineralogy (2001)
Crystallography of Schorl
Crystal SystemHexagonal
Anthony et al, Handbook of mineralogy (2001)
HabitCrystals prismatic to acicular, or may be flattened, with prominent trigonal prism and pyramid, to 1.5 m. Commonly hemimorphic, and striated. Also radial, fibrous, and massive.
Anthony et al, Handbook of mineralogy (2001)
Geological Environment
Where found:In granites and granite pegmatites, high temperature hydrothermal veins, and some metamorphic rocks; also detrital.
Anthony et al, Handbook of mineralogy (2001)
Further Information
Mineral information:Schorl information at mindat.org
Significant Gem Localities
India
 
  • Rajasthan (Rajputana)
    • Ajmer Division
Madagascar
 
  • Alaotra-Mangoro
    • Ambatondrazaka
Madagascar, extraLapis English No.1, 2001, p. 46
Madagascar, extraLapis English No.1, 2001, p. 46
  • Vakinankaratra
    • Betafo
      • Mahaiza
E.Ya. Kievlenko, Geology of gems, 2003, p. 112
Myanmar
 
  • Mandalay Region
    • Pyin-Oo-Lwin District
      • Mogok Township
        • Bernardmyo
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
          • Lay-tha Taung
Ted Themelis (2008) Gems & mines of Mogok
        • Chaung-gyi
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
        • Kathé (Kathe)
Ted Themelis (2008) Gems & mines of Mogok
        • Kyatpyin Central
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
        • Kyatpyin North
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
        • Kyauk-Pyat-That
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
          • Thurein-taung
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
        • Mogok Valley
          • Dattaw-taung (Dattaw hill)
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
        • On-dan
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
        • Pein-Pyit (Painpyit; Pyan Pyit)
Ted Themelis (2008) Gems & mines of Mogok
Ted Themelis (2008) Gems & mines of Mogok
  • Sagaing Region (Sagaing Division)
    • Katha District
      • Wuntho Township
Ted Themelis (2008) Gems & mines of Mogok
Sri Lanka
 
  • Sabaragamuwa Province
    • Ratnapura District
      • Ratnapura
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