Tourmaline
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Formula:   Na(LiAlFe)3Al6-
(BO3)3[Si6O18](OH)4
  mineral photo

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Crystal:   Hexagonal  
Hardness:   7-7.5  
Spec. Gr.:   3.03-3.25  
Streak:   White  
Cleavage:   Very Indistinct  
Location:   Virgem Da Lapa, Minas Gerais, Brazil  

Elbaite is the green variety of tourmaline. It is found in many shades of green, and also joins pink colors to form bi-colored or multicolored tourmaline crystals. When the interior of a vertical tourmaline prism is pink or red, and the exterior or skin is green, these crystals are called watermelon tourmaline. By selective absorption of transmitted light, iron causes the green color in tourmaline. Watermelon tourmaline are usually translucent and thus will cut into beautiful cabochons for jewelry. Green tourmaline which is transparent and is free of flaws or other imperfections can be faceted into gemstones of considerable popularity. Green tourmaline crystals of good size and quality have occurred in pegmatite deposits in Minas Gerais, Brazil; Mt. Mica and South Paris in Maine; Alto Ligonha, Gile, Mozambique; and at Pala, California. Tourmaline associates easily with other gemstones: hydroxylherderite, purple apatite, aquamarine, colorless beryl, and quartz.


Bibliography: Svenek, Janoslav, Minerals, 1987, pg. 194-195.

Bancroft, Peter, Gem and Crystal Treasures, 1984, pg. 205-210.



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