Phenakite

Big Photo

Brazil
9.54 carats
© Rarestone.com

The name Phenakite derived from Greek word for "deceiver" because if its resemblance to quartz.

Phenakite is mostly water-clear, coloured stones can fade. Phenakite with its hardness, lack of distinct cleavage, rarity and high clarity can make lively interesting gemstones. The cut stones usually have weight of 1 - 2 carats, rarely up to 12 carats.

Phenakite is found predominantly in Russia in association with Alexandrite, in Brazil, in Nigeria, in Burma and in Madagascar.

Phenakite Gemstones by Colour

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

Phenakite Gemstones by Size

This table shows distribution of Phenakite 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:0.41 cts
Heaviest:9.54 cts
Average:1.99 cts
Total photos:15
Do you have a larger Phenakite? Why not upload a photo?
0.41ct to 1.32ct1.32ct to 2.24ct2.24ct to 3.15ct3.15ct to 4.06ct4.06ct to 4.98ct4.98ct to 5.89ct5.89ct to 6.80ct6.80ct to 7.71ct7.71ct to 8.63ct8.63ct to 9.54ct
General Information
Chemical Formula
Be
 
2
SiO
 
4
Michael O’Donoghue, Gems, Sixth Edition (2006)
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Photos of natural/un-cut material from mindat.org
Phenakite Treatments
Colorless material has been reported to turn a yellow-brown color on irradiation (Pough and Rogers, 1947). One could expect this change to be reversed by heating - Nassau (1984)
Physical Properties of Phenakite
Mohs Hardness7.5 to 8
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
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Specific Gravity2.90 to 2.98
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
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TenacityBrittle
Arthur Thomas, Gemstones (2009)
Cleavage QualityGood
Walter Schumann, Gemstones of the world (2001)
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FractureConchoidal
Walter Schumann, Gemstones of the world (2001)
Optical Properties of Phenakite
Refractive Index1.650 to 1.695
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
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Optical CharacterUniaxial/+
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
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Birefringence0.016
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
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PleochroismDistinct: colorless - orangy-yellow
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
Dispersion0.015
Arthur Thomas, Gemstones (2009)
Colour
Colour (General)Colourless, yellowish, pink, greenish blue
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
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TransparencyTransparent
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
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LustreVitreous
Arthur Thomas, Gemstones (2009)
Fluorescence & other light emissions
Fluorescence (General)Inert to weak greenish, blue, pink
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
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Fluorescence (X-RAY)Specimens show a distinct blue
Michael O’Donoghue, Gems, Sixth Edition (2006)
Crystallography of Phenakite
Crystal SystemTrigonal
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
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HabitRhombohedral, tabular to prismatic crystals
Michael O’Donoghue, Gems, Sixth Edition (2006)
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Geological Environment
Where found:Phenakite occurs in granite pegmatites.
Michael O’Donoghue, Gems, Sixth Edition (2006)
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Inclusions in Phenakite
(Veils of) 2-phase inclusions, rutile needles - Blue Chart Gem Identification, Herve Nicolas Lazzarelli, 2010, p 4
Further Information
Mineral information:Phenakite information at mindat.org
Significant Gem Localities
Austria
 
  • Salzburg
    • Nasenkopf
    • Zell am See District
      • Mittersill
France
 
  • Grand Est
Myanmar
 
  • Mandalay Region
    • Pyin-Oo-Lwin District
Russia
 
  • Sverdlovsk Oblast
    • Malyshevo
      • Izumrudnye Kopi area
Sri Lanka
 
  • Sabaragamuwa Province
    • Ratnapura District
      • Ratnapura
USA
 
  • Virginia
Gems, Sixth Edition, Michael O’Donoghue, 2006, p. 437
Copyright © Jolyon & Katya Ralph 1993-2019. Site Map. Locality, gem & photograph data are the copyright of the individuals who submitted them. For more information please contact the . Gemdat.org is an online information resource dedicated to providing free gemmological information to all.