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www.mineralgallery.co.za Minerals A-E |
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Chrysoberyl |
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Name
Chrysoberyl
Chemistry
BeAl2O4
Uses
As a gemstone faceted for the jewelry trade.
Color
Yellow, orange-yellow, yellow-green, green, bluish green and brown. The variety alexanderite becomes reddish in artificial light.
Hardness
8,5
Specific gravity
3.5-3.8
Crystals
It forms tabular crystals in the orthorhombic crystal system
Accompanied by:
Mica
Fracture
Uneven to conchoidal
Luster
Vitreous
Cleavage
Prismatic, poor
Streak
White
Similar to:
Very similar to beryl but is slightly harder
Chrysoberyl a rare mineral , a beryllium aluminum oxide, produces the gemstones alexandrite and cat's-eye.
Common chrysoberyl occurs as crystals or loose, rounded grains in granitic pegmatites, and in metamorphic rocks such as schist and gneiss. Its tabular crystals (orthorhombic system) are transparent to translucent, yellowish green to green or brown, and have a vitreous luster. It is a vitreous, hard and tough gem. Specimens are always valuable. They are usually yellow or brown.
The variety called Alexanderite exhibits different colors in natural or artificial light. If viewed in sunlight it's color is dark yellow-green to greenish-blue. If viewed in artificial light, it's color is red.
The other expensive variety of Chrysoberyl is called cat's eye. The exhibit a narrow band of light along the width of the gem when polished as a cabochon. The crystal has slender parallel fibers which causes the light to be concentrated along the width.The cymophane variety of cat's eye exhibits a billowy, floating light reflection on it's polished surface.
Chrysotile is the yellow, transparent variety of chrysoberyl
