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Colemanite

Big Photo

Boron, Kern County, California, USA
9.33 carats
© Rarestone.com

3 photos

Colemanite Gemstones by Colour

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

Colemanite Gemstones by Size

This table shows distribution of Colemanite 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:0.87 cts
Heaviest:9.33 cts
Average:4.08 cts
Total photos:3
Do you have a larger Colemanite? Why not upload a photo?
0.87ct to 1.72ct1.72ct to 2.56ct2.56ct to 3.41ct3.41ct to 4.25ct4.25ct to 5.10ct5.10ct to 5.95ct5.95ct to 6.79ct6.79ct to 7.64ct7.64ct to 8.48ct8.48ct to 9.33ct
General Information
Chemical Formula
Ca
 
2
B
 
6
O
 
11
 · 5H
 
2
O
Michael O’Donoghue, Gems, Sixth Edition (2006)
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Physical Properties of Colemanite
Mohs Hardness4.5
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
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Specific Gravity2.40 to 2.42
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
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TenacityBrittle
Michael O’Donoghue, Gems, Sixth Edition (2006)
Cleavage QualityPerfect
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
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FractureUneven
Arthur Thomas, Gemstones (2009)
Optical Properties of Colemanite
Refractive Index1.584 to 1.615
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
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Optical CharacterBiaxial/+
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
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Birefringence0.028 to 0.030
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
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PleochroismNil
Arthur Thomas, Gemstones (2009)
DispersionRelatively weak
Arthur Thomas, Gemstones (2009)
Colour
Colour (General)Colourless, white
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
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TransparencyTransparent,Translucent
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
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LustreVitreous
Arthur Thomas, Gemstones (2009)
Fluorescence & other light emissions
Fluorescence (General)Commonly white or green
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
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Crystallography of Colemanite
Crystal SystemMonoclinic
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
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HabitEquant to short-prismatic crystals
Michael O’Donoghue, Gems, Sixth Edition (2006)
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Geological Environment
Where found:Colemanite is a common constituent of borate deposits formed in sodium- and carbonate-poor lake environments.
Michael O’Donoghue, Gems, Sixth Edition (2006)
Further Information
Mineral information:Colemanite information at mindat.org
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