Euclase

Big Photo

Pear Euclase
5.78 carats
© Rarestone.com

Euclase (Greek - breaks well) is a name that refers to the easy cleavage of this mineral.

Flawless gem rough above 1 gram is very rare. It is usually colourless, sapphire blue or blue-green. Most appreciated are bright, blue sapphire-like stones.

Euclase Gemstones by Colour

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

Euclase Gemstones by Size

This table shows distribution of Euclase 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:1.25 cts
Heaviest:9.68 cts
Average:4.85 cts
Total photos:7
Do you have a larger Euclase? Why not upload a photo?
1.25ct to 2.09ct2.09ct to 2.94ct2.94ct to 3.78ct3.78ct to 4.62ct4.62ct to 5.47ct5.47ct to 6.31ct6.31ct to 7.15ct7.15ct to 7.99ct7.99ct to 8.84ct8.84ct to 9.68ct
General Information
Chemical Formula
BeAlSiO
 
4
(OH)
Michael O’Donoghue, Gems, Sixth Edition (2006)
More from other references
Photos of natural/un-cut material from mindat.org
Euclase Treatments
Blue and green may be produced by irradiation of colorless stones - Blue Chart Gem Identification, Herve Nicolas Lazzarelli, 2010, p 4
Physical Properties of Euclase
Mohs Hardness7.5
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
More from other references
Specific Gravity3.08 to 3.12
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
More from other references
TenacityBrittle
Walter Schumann, Gemstones of the world (2001)
Cleavage QualityPerfect
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) 1 perfect and easy cleavageMore from other references
FractureConchoidal
Walter Schumann, Gemstones of the world (2001)
Optical Properties of Euclase
Refractive Index1.650 to 1.677
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
More from other references
Optical CharacterBiaxial/+
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
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Birefringence0.019 to 0.025
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
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PleochroismWeak: colorless-(greenish) - yellow-green - blue-green
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
Dispersion0.016
Arthur Thomas, Gemstones (2009)
Colour
Colour (General)Colourless, greenish, bluish, greenish-blue, blue
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
More from other references
Colour (Chelsea Filter)Blue variety often shows red
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
Causes of ColourBlue Fe2+-O-Fe3+ charge transfer. Green Cr3+ in octahedral coordination
W. William Hanneman, Pragmatic Spectroscopy For Gemologists (2011)
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)Weak or none
Walter Schumann, Gemstones of the world (2001)
Crystallography of Euclase
Crystal SystemMonoclinic
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
More from other references
HabitFlattened prismatic
Michael O’Donoghue, Gems, Sixth Edition (2006)
More from other references
Geological Environment
Where found:Euclase is found in pegmatites and is formed from the decomposition of beryl.
Michael O’Donoghue, Gems, Sixth Edition (2006)
Further Information
Mineral information:Euclase information at mindat.org
Significant Gem Localities
Brazil
 
  • Minas Gerais
      • Rodrigo Silva district
        • Boa Vista
Gems, Sixth Edition, Michael O’Donoghue, 2006, p. 410
    • São Sebastião do Maranhão
Colombia
 
  • Boyacá Department
    • Guavió-Guatéque mining district
      • Mun. de Chivor
Emeralds of the World English extraLapis Vol. 2 2002 pp36-45
    • Mun. de Pauna
Fabre Minerals.
Myanmar
 
  • Mandalay Region
    • Pyin-Oo-Lwin District
      • Mogok Township
        • Mogok Valley
Ted Themelis (2008) Gems & mines of Mogok
Zimbabwe
 
  • Mashonaland West
    • Karoi District (Urungwe; Hurungwe District)
Gems, Sixth Edition, Michael O’Donoghue, 2006, p. 410
Copyright © Jolyon & Katya Ralph 1993-2018. 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.