Boracite

Boracite is named after its boron content.

Boracite produces crystals of various colours with vitreous to adamantine lustre. It has good clarity and hardness, but it is slightly soluble in water. This fact limits the use of boracite as a gemstone.

Faceted stones seldom exceed 1 carat in weight and are quite rare.

Boracite Gemstones by Colour

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

Boracite Gemstones by Size

This table shows distribution of Boracite 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:0.27 cts
Heaviest:.63 cts
Average:0.40 cts
Total photos:3
Do you have a larger Boracite? Why not upload a photo?
0.27ct to 0.31ct0.31ct to 0.34ct0.34ct to 0.38ct0.38ct to 0.41ct0.41ct to 0.45ct0.45ct to 0.49ct0.49ct to 0.52ct0.52ct to 0.56ct0.56ct to 0.59ct0.59ct to 0.63ct
General Information
Chemical Formula
Mg
 
3
B
 
7
O
 
13
Cl
Michael O’Donoghue, Gems, Sixth Edition (2006)
More from other references
Photos of natural/un-cut material from mindat.org
Physical Properties of Boracite
Mohs Hardness7 to 7.5
Walter Schumann, Gemstones of the world (2001)
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Specific Gravity2.95 to 2.96
Walter Schumann, Gemstones of the world (2001)
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TenacityBrittle
Arthur Thomas, Gemstones (2009)
Cleavage QualityPoor
Arthur Thomas, Gemstones (2009)
FractureConchoidal
Arthur Thomas, Gemstones (2009)
Optical Properties of Boracite
Refractive Index1.658 to 1.673
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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Birefringence0.010 to 0.011
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
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PleochroismNil
Arthur Thomas, Gemstones (2009)
DispersionNil
Arthur Thomas, Gemstones (2009)
Colour
Colour (General)Light green, colourless, white, yellow, bluish.
Walter Schumann, Gemstones of the world (2001)
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TransparencyTransparent,Translucent
Walter Schumann, Gemstones of the world (2001)
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LustreAdamantine,Vitreous
Michael O’Donoghue, Gems, Sixth Edition (2006)
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Fluorescence & other light emissions
Fluorescence (General)Very weak greenish fluorescence
Michael O’Donoghue, Gems, Sixth Edition (2006)
Crystallography of Boracite
Crystal SystemOrthorhombic
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
More from other references
HabitPseudo-cubic, octahedrons, dodecahedrons, tetrahedrons
Arthur Thomas, Gemstones (2009)
Geological Environment
Where found:Boracite is found in evaporite deposits, usually associated with gypsum, anhydrite and/or halite.
Arthur Thomas, Gemstones (2009)
Further Information
Mineral information:Boracite information at mindat.org
Significant Gem Localities
Germany
 
  • Saxony-Anhalt
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