Difference between revisions of "Paraiba"

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[[Image:Paraiba1.jpg|left|thumb|250px|Brazilian Paraiba tourmaline <br /> Photo courtesy of Lembeck Gems]]<br clear="left" />
 
[[Image:Paraiba1.jpg|left|thumb|250px|Brazilian Paraiba tourmaline <br /> Photo courtesy of Lembeck Gems]]<br clear="left" />
  
[[Image:Mozparaiba.jpg|left|thumb|250px|Mozambique "Paraiba-type" tourmaline, 3.71 ct, heated <br />Photo courtesy of Precision Gem]]<br clear="left" />
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[[Image:Mozparaiba.jpg|left|thumb|250px|Mozambique "Paraiba-type" tourmaline 3.71 ct <br />Photo courtesy of Precision Gem]]<br clear="left" />
  
[[Image:6403_d.jpg|left|thumb|250px|Nigerian "Paraiba-type" tourmaline, 1.53 ct <br />Photo by Jeff Scovil, Courtesy of R.W. Wise Goldsmiths]]<br clear="left" />
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[[Image:6403_d.jpg|left|thumb|250px|Nigerian "Paraiba-type" tourmaline, 1.53 ct <br />Photo by Jeff Scovil<br /> Courtesy of R.W. Wise Goldsmiths]]<br clear="left" />
  
[[Image:Purplecuprian.jpg|left|thumb|250px|Mozambique "Paraiba-type" tourmaline, 8.14 ct, unheated <br />Photo by Jeff Scovil, Courtesy of R.W. Wise Goldsmiths]]<br clear="left" />
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[[Image:Purplecuprian.jpg|left|thumb|250px|Mozambique "Paraiba-type" tourmaline, <br />8.14 ct, unheatedPhoto by Jeff ScovilCourtesy of R.W. Wise Goldsmiths]]<br clear="left" />

Revision as of 07:17, 10 April 2007

Paraiba Tourmaline
Chemical composition Complex borosilicate
Crystal system Trigonal
Habit Prismatic
Cleavage None
Fracture Conchoidal
Hardness 7.5
Optic nature Uniaxial -
Refractive index 1.62 - 1.64
Birefringence 0.014 - 0.022
Dispersion Low, 0.018
Specific gravity 3.06
Lustre Vitreous
Pleochroism Weak to strong
Brazilian Paraiba tourmaline
Photo courtesy of Lembeck Gems

Mozambique "Paraiba-type" tourmaline 3.71 ct
Photo courtesy of Precision Gem

Nigerian "Paraiba-type" tourmaline, 1.53 ct
Photo by Jeff Scovil
Courtesy of R.W. Wise Goldsmiths

Mozambique "Paraiba-type" tourmaline,
8.14 ct, unheated. Photo by Jeff Scovil. Courtesy of R.W. Wise Goldsmiths