Labradorite

Big Photo

Madagascar
9.6 carats
© gemselect.com

A type of feldspar consisting of between 30-50% Albite and 50-70% Anorthite.

Labradorite was named after peninsula of Labrador in Canada, where it was first found.

It shows labradorescence - a shiller effect in lustrous metallic tints, often blue and green, and sometimes the complete spectrum. This effect is caused by interference of light from lattice distortions resulting from alternating microscopic exsolution lamellae of high- and low-calcium plagioclase phases.

Labradorite Gemstones by Colour

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

Labradorite Gemstones by Size

This table shows distribution of Labradorite 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:2.53 cts
Heaviest:145.2 cts
Average:34.79 cts
Total photos:21
Do you have a larger Labradorite? Why not upload a photo?
2.53ct to 16.80ct16.80ct to 31.06ct31.06ct to 45.33ct45.33ct to 59.60ct59.60ct to 73.87ct73.87ct to 88.13ct88.13ct to 102.40ct102.40ct to 116.67ct116.67ct to 130.93ct130.93ct to 145.20ct
General Information
A variety or type of:Feldspar
Varieties/Types:
Spectrolite - Trade name for a Labradorite from Finland that shows the spectral colours especially effectively.
Chemical Formula
Na(30-50%)Ca(70-50%)(Al,Si)AlSi
 
2
O
 
8
Michael O’Donoghue, Gems, Sixth Edition (2006)
Photos of natural/un-cut material from mindat.org
Physical Properties of Labradorite
Mohs Hardness6 to 6.5
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
More from other references
Specific Gravity2.69 to 2.72
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
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TenacityBrittle
Michael O’Donoghue, Gems, Sixth Edition (2006)
Cleavage QualityPerfect
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
More from other references
FractureUneven
Michael O’Donoghue, Gems, Sixth Edition (2006)
Optical Properties of Labradorite
Refractive Index1.554 to 1.573
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
More from other references
Optical CharacterBiaxial/+
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
More from other references
Birefringence0.007 to 0.011
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
More from other references
PleochroismFrom the Congo, red stones show weak pleochroism whilst greenstones have distinct greenish yellow to bluish green pleochroism
Michael O’Donoghue, Gems, Sixth Edition (2006)
DispersionLow (0.012)
Michael O’Donoghue, Gems, Sixth Edition (2006) But the combination of a high polish and minute inclusions can simulate the effect of moderate dispersion
Colour
Colour (General)Dark gray, black-gray, labradorescent: blue-green, golden yellow, purple, bronze colour
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
More from other references
Causes of ColourMulticolors, diffraction of light by the internal lamellar structure. Red (in the material from Oregon), submicroscopic metallic copper particles. Green and orange could be Cu+
W. William Hanneman, Pragmatic Spectroscopy For Gemologists (2011)
TransparencyTransparent,Translucent,Opaque
Walter Schumann, Gemstones of the world (2001)
More from other references
LustreVitreous
Michael O’Donoghue, Gems, Sixth Edition (2006)
Fluorescence & other light emissions
Fluorescence (Short Wave UV)The intensity is diminished and fluorescence is a weak chalky pinkish orange
Michael O’Donoghue, Gems, Sixth Edition (2006)
Fluorescence (Long-Wave UV)Red stones (Congo) fluoresced weak to distinct orange and greenstones (Congo) appeared distinctly orange
Michael O’Donoghue, Gems, Sixth Edition (2006)
Crystallography of Labradorite
Crystal SystemTriclinic
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
More from other references
HabitPlaty, prismatic
Walter Schumann, Gemstones of the world (2001)
More from other references
Geological Environment
Where found:A common constituent of anorthosites, norites, basalts and gabbros as well as other igneous rocks. In the metamorphic environment it occurs in gneisses derived from basic rocks.
Michael O’Donoghue, Gems, Sixth Edition (2006)
Inclusions in Labradorite
Transparent stones: common elongated black inclusions (ilmenite) - Blue Chart Gem Identification, Herve Nicolas Lazzarelli, 2010, p 6
Red hematite platelets, black magnetite needles, ilmenite - Gemmological Tables, Ulrich Henn and Claudio C. Milisenda, 2004, p 10
Further Information
Mineral information:Labradorite information at mindat.org
Significant Gem Localities
Myanmar
 
  • Mandalay Division
    • Pyin-Oo-Lwin District
      • Mogok Township
        • Kyauk-Pyat-That
Ted Themelis (2008) Gems & mines of Mogok
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