Difference between revisions of "Topaz"

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{{Topaz}}
 
{{Topaz}}
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[[Image:Imperial4.jpg|left|framed|Peach Pink Imperial Topaz<br />Photo courtesy of Lembeck Gems]]<br clear="left" />

Revision as of 02:34, 10 January 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