Brazil
Rio Grande do Norte
Carrasc„o Pegmatite


  The beautiful, electric blue tourmaline known a Paraiba Tourmaline from northeastern Brazil is generally elbaite to fluor-elbaite. A single point analysis by Geurlen et al. (2011) of a zoned schorl-elbaite crystal from the Carrasc„o pegmatite in quartzites that contain relic grains of multicolored elbaite, mostly replaced by lepidolite, found a composition that enters the rossmanite field.

X-site composition

[]=0.502
Na 0.486
Ca 0.01

composition diagram


References:

Beurlen H, de Moura OJM, Soares DR, Da Siliva MRR, Rhede D (2011) Geochemical and geological controls on  the genesis of gem-quality "Paraiba Tourmaline" in granitic pegmatites from northeastern Brazil. The Canadian Mineralogist 49, 277-300. 


last updated: 12-Jul-2014