Difference between revisions of "Diaspore"
From The Gemology Project
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[[Image:Diasporeccwz3.jpg|thumb|left|300px|Color-changing diaspore from green in daylight to brown in incandescent light - also known as “Zultanite” in the gem market.<br />Photo courtesy of Chaman Golecha, Gem Testing Laboratory, Jaipur.]] | [[Image:Diasporeccwz3.jpg|thumb|left|300px|Color-changing diaspore from green in daylight to brown in incandescent light - also known as “Zultanite” in the gem market.<br />Photo courtesy of Chaman Golecha, Gem Testing Laboratory, Jaipur.]] | ||
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− | Diaspore as a gemstone has been reported first around 1977 when a large enough crystal was examined at the Gem Testing Laboratory in London. This, usually colorless, material showed good color-change from pale bluish-green to pale pinkish-brown. Turkey was the origin of this color-change material. | + | Diaspore as a plausible gemstone has been reported first around 1977 when a large enough crystal was examined at the Gem Testing Laboratory in London. This, usually colorless, material showed good color-change from pale bluish-green to pale pinkish-brown. Turkey was the origin of this color-change material. |
When Zultanite Gems LLC aquired the mining location, this color-change variety of diaspore was marketed under the tradename "zultanite®". At present (2007) sole distribution rights of "zultanite®" are granted to GemsTV. | When Zultanite Gems LLC aquired the mining location, this color-change variety of diaspore was marketed under the tradename "zultanite®". At present (2007) sole distribution rights of "zultanite®" are granted to GemsTV. |
Revision as of 08:29, 30 August 2007
Diaspore | |
---|---|
Chemical composition | AlO(OH) |
Crystal system | Orthorhombic |
Habit | Tabular, sometimes fibrous |
Cleavage | Perfect to imperfect |
Fracture | Conchoidal |
Luster | Bright vitreous to pearly (on cleavage surface). |
Hardness | 6.5 - 7 |
Optic nature | Biaxial + |
Refractive index | 1.682 - 1.752 |
Birefringence | 0.040 - 0.048 |
Specific gravity | 3.2 - 3.5 |
Lustre | Vitreous |
Pleochroism | Moderate |
Diaspore as a plausible gemstone has been reported first around 1977 when a large enough crystal was examined at the Gem Testing Laboratory in London. This, usually colorless, material showed good color-change from pale bluish-green to pale pinkish-brown. Turkey was the origin of this color-change material.
When Zultanite Gems LLC aquired the mining location, this color-change variety of diaspore was marketed under the tradename "zultanite®". At present (2007) sole distribution rights of "zultanite®" are granted to GemsTV.