Difference between revisions of "Paraiba"
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{{Paraiba}} | {{Paraiba}} | ||
− | [[Image: | + | [[Image:Paraiba1.jpg|left|thumb|250px|Brazilian Paraiba tourmaline <br /> Photo courtesy of Lembeck Gems]]<br clear="all" /> |
− | [[Image:Mozparaiba.jpg| | + | ==Paraiba type== |
+ | |||
+ | {| align="center" {{table}} style="margin:0;" | ||
+ | |- | ||
+ | |align="center"| | ||
+ | [[Image:Mozparaiba.jpg|200px]] | ||
+ | |align="center"| | ||
+ | [[Image:6403_d.jpg|200px]] | ||
+ | |align="center"| | ||
+ | [[Image:Purplecuprian.jpg|200px]] | ||
+ | |- | ||
+ | |width="33%" align="center"|Mozambique "Paraiba-type" tourmaline 3.71 ct <br />Photo courtesy of Precision Gem | ||
+ | |width="33%" align="center"|Nigerian "Paraiba-type" tourmaline, 1.53 ct <br />Photo by Jeff Scovil<br /> Courtesy of R.W. Wise Goldsmiths | ||
+ | |width="34%" align="center"|Mozambique "Paraiba-type" tourmaline, 8.14 ct, unheated.<br />Photo by Jeff Scovil.<br />Courtesy of R.W. Wise Goldsmiths | ||
+ | |} |
Latest revision as of 05:54, 21 June 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 |
Paraiba type
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 |