Kornerupine

Big Photo

Sri Lanka
12.20 carats
© Palagems

Kornerupine was named after a Danish geologist and explorer A. N. Kornerup.

The colour can vary from brown, green to shades of yellow, the material is strongly pleochroic and frequently asteriated (from Burma and Taita Hills, Kenya). Cat's eye effect is due to inclusions of rutile and graphite.

Kornerupine can be faceted or cut into cabochons. Cut stones are up to 20 carats (usually to 3 carats).

Kornerupine Gemstones by Colour

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

Kornerupine Gemstones by Size

This table shows distribution of Kornerupine 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:0.08 cts
Heaviest:12.20 cts
Average:2.00 cts
Total photos:13
Do you have a larger Kornerupine? Why not upload a photo?
0.08ct to 1.29ct1.29ct to 2.50ct2.50ct to 3.72ct3.72ct to 4.93ct4.93ct to 6.14ct6.14ct to 7.35ct7.35ct to 8.56ct8.56ct to 9.78ct9.78ct to 10.99ct10.99ct to 12.20ct
General Information
Chemical Formula
Mg
 
3
Al
 
6
(Si,Al,B)
 
5
O
 
21
(OH)
Walter Schumann, Gemstones of the world (2001)
More from other references
Photos of natural/un-cut material from mindat.org
Physical Properties of Kornerupine
Mohs Hardness6.5
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
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Specific Gravity3.25 to 3.45
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
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Cleavage QualityGood
Walter Schumann, Gemstones of the world (2001)
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FractureConchoidal
Arthur Thomas, Gemstones (2009)
Optical Properties of Kornerupine
Refractive Index1.660 to 1.685
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
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Optical CharacterBiaxial/-
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
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Birefringence0.012 to 0.017
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
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PleochroismStrong trichroism is common for green variety: green - yellow - reddish brown
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
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Dispersion0.018
Arthur Thomas, Gemstones (2009)
ChatoyancyRare star 4
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
Colour
Colour (General)Green, blue-green, brownish-green, greenish-brown
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
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Causes of ColourBlue, Cr3+ in octahedral coordination. Green, V3+ 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)Usually none; green kornerupine from Kenya: yellow
Walter Schumann, Gemstones of the world (2001)
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Crystallography of Kornerupine
Crystal SystemOrthorhombic
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
More from other references
HabitPrismatic
Michael O’Donoghue, Gems, Sixth Edition (2006)
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Geological Environment
Where found:Occurs in boron-rich volcanic and sedimentary rocks subjected to metamorphism
Michael O’Donoghue, Gems, Sixth Edition (2006)
Inclusions in Kornerupine
Common needle-like inclusions: sharp cat's eye (grayish, greenish, black)- Blue Chart Gem Identification, Herve Nicolas Lazzarelli, 2010, p 4
Needle-like crystals, zircons with tension cracks - Gemmological Tables, Ulrich Henn and Claudio C. Milisenda, 2004, p 19
Further Information
Mineral information:Kornerupine information at mindat.org
Significant Gem Localities
Australia
 
  • Northern Territory
    • Central Desert Region
      • Harts Range (Harts Ranges; Hartz Range; Hartz Ranges)
Denmark
 
  • Greenland
    • Sermersooq
      • Nuuk (Godthåb)
Kenya
 
  • Kwale County
Gems, Sixth Edition, Michael O’Donoghue, 2006, p. 421
  • Taita-Taveta County
Collection of NHM, Vienna
Madagascar
 
  • Anosy
    • Betroka
      • Mahasoa Est
Gems, Sixth Edition, Michael O’Donoghue, 2006, p. 421
Myanmar
 
  • Mandalay Region
    • Pyin-Oo-Lwin District
        • Chaung-gyi
Ted Themelis (2008) Gems & mines of Mogok
        • Mogok Valley
Gems, Sixth Edition, Michael O’Donoghue, 2006, p. 421
        • Pein-Pyit (Painpyit; Pyan Pyit)
Ted Themelis (2008) Gems & mines of Mogok
Sri Lanka
 
  • Central Province
  • Southern Province
    • Matara District
      • Matara
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.