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Elbaite



Elbaite

General
CategorySilicate mineral
Chemical formulaNa(LiAl)3Al6Si6O18(BO3)3(OH)4
Identification
ColorGreen, red to pink, blue, orange, yellow, colorless, multicolored
Crystal habitPrismatic; striated
Crystal systemTrigonal
CleavagePoor/Indistinct on {1120} and {1011}
FractureSub Conchoidal
Mohs Scale hardness
LusterVitreous
Refractive indexnω = 1.635 - 1.650 nε = 1.615 - 1.632
Optical PropertiesUniaxial (-)
Birefringenceδ = 0.020
StreakWhite
Density2.9 - 3.2
DiaphaneityTransparent to opaque
References[1][2]
Major varieties
Achroitecolorless
Indicoliteblue
Rubellitered to pink
Verdelitegreen

Elbaite, a sodium, lithium, aluminium borosilicate, is a mineral species belonging to the tourmaline group. Elbaite forms three series, with dravite, with liddicoatite, and with schorl. Due to these series specimens with the ideal end-member formula are not found occurring natually.

Additional recommended knowledge

As a gemstone, elbaite is reckoned to be one of the most desirable of the tourmaline group because of the variety and depth of its colours and quality of the crystals. Originally discovered on the Island of Elba, Italy in 1913 it has since been found in many parts of the world. In 1994 a major locality was discovered in Canada, at O'Grady Lakes in the Yukon.


References

  1. ^ http://www.mindat.org/min-1364.html Mindat
  2. ^ http://webmineral.com/data/Elbaite.shtml Webmineral data
 
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Elbaite". A list of authors is available in Wikipedia.
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