Simpsonite

Big Photo

Brazil
0.20 carats
© Rarestone.com

Simpsonite is named after E.S. Simpson, Government mineralogist and analyst of Western Australia, where the mineral was first doscovered in the Tabba Tabba pegmatite.

Simpsonite forms transparent to translucent, yellow, orange to brown, sometimes colourless tabular to short prismatic crystals with an adamantine lustre.

Simpsonite is cut into attractive, colourful, bright and durable gems, but the amount of facet rough is limited.

Simpsonite Gemstones by Colour

This table shows the variety of hues this gemstone can be found in. Click on a photo for more information.
 
General Information
Chemical Formula
Al
 
4
(Ta,Nb)
 
3
(O,OH,F)
 
14
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
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Photos of natural/un-cut material from mindat.org
Physical Properties of Simpsonite
Mohs Hardness7 to 7.5
Walter Schumann, Gemstones of the world (2001)
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Specific Gravity5.90 to 7.30
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
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TenacityBrittle
Arthur Thomas, Gemstones (2009)
Cleavage QualityIndistinct
Arthur Thomas, Gemstones (2009)
FractureConchoidal
Anthony et al, Handbook of mineralogy (2001)
Optical Properties of Simpsonite
Refractive Index1.994 to 2.040
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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Birefringence0.046
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
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PleochroismNil
Arthur Thomas, Gemstones (2009)
DispersionNil
Arthur Thomas, Gemstones (2009)
Colour
Colour (General)Orange, colourless, white, brownish-yellow.
Walter Schumann, Gemstones of the world (2001)
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TransparencyTranslucent
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
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LustreAdamantine,Vitreous
Walter Schumann, Gemstones of the world (2001)
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Fluorescence & other light emissions
Fluorescence (Short Wave UV)Crystals from western Australia show a bright blue-white
Michael O’Donoghue, Gems, Sixth Edition (2006)
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Crystallography of Simpsonite
Crystal SystemTrigonal
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
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HabitTabular to short prismatic
Michael O’Donoghue, Gems, Sixth Edition (2006)
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Geological Environment
Where found:Simpsonite occurs as an accessory mineral in some Ta-rich granite pegmatites.
Michael O’Donoghue, Gems, Sixth Edition (2006)
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Further Information
Mineral information:Simpsonite information at mindat.org
Significant Gem Localities
Australia
 
  • Western Australia
    • Port Hedland Shire
      • Wallareenya Station
Gems, Sixth Edition, Michael O’Donoghue, 2006, p. 452
Brazil
 
  • Rio Grande do Norte
    • Equador
Gems, Sixth Edition, Michael O’Donoghue, 2006, p. 452
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