Sugilite

Big Photo

Australia
15.15 carats
© gemselect.com

Sugilite is named after Ken-ichi Sugi, Japanese petrologist who first discovered the mineral on Iwagi island, Shikoku, Japan in 1994.

Sugilite most commonly forms compact masses with a light brownish yellow to a bright magenta colour. The material yields attractive cabochons, beads, ornamental objects. Semi-transparent stones are occasionally faceted. Crystal specimens are very rare.

Sugilite is also known as Wesselite, because translucent facetable material of intense purple colour was found in the Wessels Manganese Mine near Hotazel, South Africa.

The name Cybelene has also been used for Sugilite.

Sugilite Gemstones by Colour

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

Sugilite Gemstones by Size

This table shows distribution of Sugilite 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:12.41 cts
Heaviest:74.11 cts
Average:27.41 cts
Total photos:21
Do you have a larger Sugilite? Why not upload a photo?
12.41ct to 18.58ct18.58ct to 24.75ct24.75ct to 30.92ct30.92ct to 37.09ct37.09ct to 43.26ct43.26ct to 49.43ct49.43ct to 55.60ct55.60ct to 61.77ct61.77ct to 67.94ct67.94ct to 74.11ct
General Information
Other Names/Trade Names:
Chemical Formula
KNa
 
2
(Fe
3+
 
,Mn
3+
 
,Al)
 
2
Li
 
3
Si
 
12
O
 
30
Michael O’Donoghue, Gems, Sixth Edition (2006)
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Photos of natural/un-cut material from mindat.org
Sugilite Treatments
It has been noted by J.Call (unpublished observation) that dark purple sugilite can be lightened by heating at about 450°C; the product may have a banded appearance - Nassau (1984)
Sugilite Simulants
May be mixed with chalcedony - Blue Chart Gem Identification, Herve Nicolas Lazzarelli, 2010, p 5
Physical Properties of Sugilite
Mohs Hardness5.5 to 6.5
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
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Specific Gravity2.69 to 2.79
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
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Cleavage QualityPoor
Arthur Thomas, Gemstones (2009)
FractureSub-Conchoidal
Arthur Thomas, Gemstones (2009)
Optical Properties of Sugilite
Refractive Index1.607 to 1.612
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
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Optical CharacterUniaxial/-
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
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Birefringence0.003 to 0.005
Michael O’Donoghue, Gems, Sixth Edition (2006)
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PleochroismWeak
Anthony et al, Handbook of mineralogy (2001)
Colour
Colour (General)Violet, purple-red
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
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Causes of ColourPurple, Mn3+ and Fe3+ presumably in octahedral coordination
W. William Hanneman, Pragmatic Spectroscopy For Gemologists (2011)
TransparencyTranslucent,Opaque
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) Opaque to semi-transparentMore from other references
LustreResinous
Walter Schumann, Gemstones of the world (2001)
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Crystallography of Sugilite
Crystal SystemHexagonal
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
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HabitMassive
Michael O’Donoghue, Gems, Sixth Edition (2006)
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Geological Environment
Where found:Sugilite occurs in an aegirine-bearing syenite stock in biotite granite in bedded manganese deposits.
Michael O’Donoghue, Gems, Sixth Edition (2006)
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Further Information
Mineral information:Sugilite information at mindat.org
Significant Gem Localities
South Africa
 
  • Northern Cape
    • Kalahari manganese field
      • Hotazel
Gems, Sixth Edition, Michael O’Donoghue, 2006, p. 457
      • Kuruman
        • N'Chwaning Mines
Gems, Sixth Edition, Michael O’Donoghue, 2006, p. 457
Gems, Sixth Edition, Michael O’Donoghue, 2006, p. 457
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