Sodalite

Big Photo

Hackmanite
Badakhshan, Afghanistan
0.35 carats
© Rarestone.com

Sodalite is named after its sodium content, it may be classed as a feldspathoid. Only blue stones are used in jewelry, sometimes they have violet tint. Sodalite may also be grey, yellow, green, or pink and is often mottled with white veins or patches.

It was first discovered in 1811 in Greenland, but became important as an ornamental stone in 1891 when vast deposits of fine material were discovered in Ontario, Canada.

Sodalite Gemstones by Colour

This table shows the variety of hues this gemstone can be found in. Click on a photo for more information.
 
 
 
 
 

Sodalite Gemstones by Size

This table shows distribution of Sodalite gemstone sizes that are listed on this site. This can give a good indication as to the general availability of this gemstone in different sizes.
Contributed photos
Lightest:0.06 cts
Heaviest:71.1 cts
Average:9.46 cts
Total photos:54
Do you have a larger Sodalite? Why not upload a photo?
0.06ct to 7.16ct7.16ct to 14.27ct14.27ct to 21.37ct21.37ct to 28.48ct28.48ct to 35.58ct35.58ct to 42.68ct42.68ct to 49.79ct49.79ct to 56.89ct56.89ct to 64.00ct64.00ct to 71.10ct
General Information
Varieties/Types:
Hackmanite - Pink to grey-white to white variety of Sodalite.
Chemical Formula
Na
 
8
Al
 
6
Si
 
6
O
 
24
Cl
 
2
Michael O’Donoghue, Gems, Sixth Edition (2006)
More from other references
Photos of natural/un-cut material from mindat.org
Sodalite Treatments
Sodalite is reported to lose its color on heating and regain it on irradiation (Przibram and Caffyn, 1956), indicating the probable presence of a color center - Nassau (1984)
Physical Properties of Sodalite
Mohs Hardness5 to 6
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
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Specific Gravity2.15 to 2.40
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
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TenacityBrittle
Anthony et al, Handbook of mineralogy (2001)
Cleavage QualityIndistinct
Walter Schumann, Gemstones of the world (2001)
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FractureUneven
Arthur Thomas, Gemstones (2009)
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Optical Properties of Sodalite
Refractive Index1.478 to 1.488
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
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Optical CharacterIsotropic
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
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BirefringenceNone
Walter Schumann, Gemstones of the world (2001)
PleochroismAbsent
Walter Schumann, Gemstones of the world (2001)
Dispersion0.018
Walter Schumann, Gemstones of the world (2001)
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Colour
Colour (General)Blue, blue-violet
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
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Causes of ColourBlue, interstitial oxygen ion O- near Al or Si. Pink, (hackmanite), unstable electron substituting for Cl- in a tetrahedron of Na+ ions
W. William Hanneman, Pragmatic Spectroscopy For Gemologists (2011)
TransparencyTransparent,Translucent,Opaque
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
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LustreVitreous,Greasy
Arthur Thomas, Gemstones (2009)
Fluorescence & other light emissions
Fluorescence (General)Strong; orange
Walter Schumann, Gemstones of the world (2001)
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Crystallography of Sodalite
Crystal SystemIsometric
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
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HabitPolycrystalline aggregate, commonly with white veins
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
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Geological Environment
Where found:Formed in nepheline syenites, phonolites, and related rock types. In metasomatized calcareous rocks, and in cavities in ejected volcanic blocks.
Anthony et al, Handbook of mineralogy (2001)
Inclusions in Sodalite
White calcite patches and veins. No pyrite inclusions unlike lapis. Translucent sodalite: small black inclusions common - Blue Chart Gem Identification, Herve Nicolas Lazzarelli, 2010, p 9
Further Information
Mineral information:Sodalite information at mindat.org
Significant Gem Localities
Bolivia
 
  • Cochabamba
    • Ayopaya Province
Denmark
 
  • Greenland
    • Kujalleq
      • Narsaq
Gems, Sixth Edition, Michael O’Donoghue, 2006, p. 453
Myanmar
 
  • Mandalay Region
    • Pyin-Oo-Lwin District
[var: Hackmanite]
        • Kyatpyin North
Ted Themelis (2008) Gems & mines of Mogok
        • Marble Ark
[var: Hackmanite] Ted Themelis (2008) Gems & mines of Mogok
        • Mogok Valley
          • Dattaw-taung (Dattaw hill)
[var: Hackmanite] Ted Themelis (2008) Gems & mines of Mogok
[var: Hackmanite] Ted Themelis (2008) Gems & mines of Mogok
[var: Hackmanite] Ted Themelis (2008) Gems & mines of Mogok
[var: Hackmanite]
        • Pein-Pyit (Painpyit; Pyan Pyit)
[var: Hackmanite] Ted Themelis (2008) Gems & mines of Mogok
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