Sogdianite

Sogdianite is named after its discovery locality, in Sogdiana, the ancient name of the discovery region in central Asia.

Sogdianite forms transparent to translucent violet crystals.

Sogdianite is a very rare gem, it is highly evaluated for its beautiful colour. Sogdianite has been faceted and cut into cabochons.
General Information
Chemical Formula
(K,Na)
 
2
(Li,Fe)
 
3
(Zr,Ti,Fe)Si
 
12
O
 
30
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
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Physical Properties of Sogdianite
Mohs Hardness7
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
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Specific Gravity2.77 to 2.90
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
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Cleavage QualityPerfect
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
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Optical Properties of Sogdianite
Refractive Index1.606 to 1.608
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
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Optical CharacterUniaxial/-
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
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Birefringence0.002
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
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Colour
Colour (General)Violet
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
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TransparencyOpaque
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
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LustreVitreous
Anthony et al, Handbook of mineralogy (2001)
Fluorescence & other light emissions
Fluorescence (Short Wave UV)Very dark red
Michael O’Donoghue, Gems, Sixth Edition (2006)
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Fluorescence (Long-Wave UV)Dark violet
Michael O’Donoghue, Gems, Sixth Edition (2006)
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Crystallography of Sogdianite
Crystal SystemHexagonal
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
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HabitTabular crystals, to 1 cm; in platy aggregates, to 15 cm.
Anthony et al, Handbook of mineralogy (2001)
Geological Environment
Where found:Occurs in a pegmatite vein with a composition near that of an alkalic granite.
Michael O’Donoghue, Gems, Sixth Edition (2006)
Further Information
Mineral information:Sogdianite information at mindat.org
Significant Gem Localities
South Africa
 
  • Northern Cape
    • Kalahari manganese field
      • Hotazel
Tajikistan
 
  • Districts of Republican Subordination
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