Difference between revisions of "Topaz"

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(added imitation, synthetic and sources sections)
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[[Image:Redimper.jpg|left|thumb|250px|Red Imperial Topaz<br />Photo courtesy of Lembeck Gems]]<br clear="left" />
 
[[Image:Redimper.jpg|left|thumb|250px|Red Imperial Topaz<br />Photo courtesy of Lembeck Gems]]<br clear="left" />
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==Imitations==
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Recently,2007, yellow-orange-pink flame-fusion corundum is offered in Minas Gerais, Brazil as imperial topaz.
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==Synthetics==
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Although topaz is synthezised, the material is not commercially available.
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==Sources==
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* [http://www.gia.edu/newsroom/issue/2798/2696/insider_newsletter_details.cfm#2 From Gems & Gemology: A New Imitation of Imperial Topaz]

Revision as of 03:18, 30 June 2007

Topaz
Chemical composition Al2(F,OH)2SiO4
Crystal system Orthorhombic
Habit Prismatic with pyramidal/domed terminations
Cleavage Perfect, basal plane
Fracture Sub-conchoidal to uneven
Hardness 8
Optic nature Biaxial +
Refractive index 1.606-1.644
Birefringence 0.008 - 0.010
Dispersion Low, 0.014
Specific gravity 3.49 - 3.57
Lustre Vitreous
Pleochroism Distinct to strong (depending on body color)
Peach Pink Imperial Topaz
Photo courtesy of Lembeck Gems

Red Imperial Topaz
Photo courtesy of Lembeck Gems

Imitations

Recently,2007, yellow-orange-pink flame-fusion corundum is offered in Minas Gerais, Brazil as imperial topaz.

Synthetics

Although topaz is synthezised, the material is not commercially available.

Sources