The Gemstone Tiger's Eye
Tiger's Eye, a popular yet inexpensive gemstone, is a pseudomorph of compact Quartz after the fibrous mineral Crocidolite. It is formed when the Quartz takes over and dissolves the Crocodolite, leaving the Quartz in a finely fibrous and chatoyant form. When polished, it's silky luster creates a beautiful chatoyant effect of moving layers of brown and yellow lines and waves.
Chemical Formulaxefxbcx9a SiO2
Color xefxbcx9aYellow, Brown, Multicolored
Hardness xefxbcx9a7
Crystal System xefxbcx9aHexagonal
Refractive Index xefxbcx9a1.54 - 1.55
SG xefxbcx9a2.63 - 2.65
Transparency xefxbcx9aOpaque
Double Refraction xefxbcx9aNone
Luster xefxbcx9aSilky
Cleavage xefxbcx9aIndiscernible
Mineral Class xefxbcx9aQuartz (Chalcedony)
ALL ABOUT
Tiger's Eye forms when Quartz forms over existing bluish-gray Crocidolite, and eventually entirely replaces it. Crocidolite is a type of asbestos mineral, which means its composition is of fine, dense fibers. These fibers form in a parallel yet wavy orientation, and this causes the intriguing chatoyant effect exhibited in Tiger's Eye. During the replacement process, the iron within the Crocidolite dissolves and stains the Quartz, thereby providing the golden yellow to brown color of the Tiger's Eye.
The original Crocidolite is a bluish-gray color, and sometimes the pseudomorphism to Quartz is incomplete. When this happens, the result is a stone with a bluish-gray color (and often with streaks or overtones of brown or yellow), but still with chatoyant effect. This type of material is known as as Hawk's Eye.
Tiger's Eye may form together with brownish-red or metallic-gray Hematite, or with yellow Limonite, where these minerals forms stripes, streaks, or patterns within the Tiger's Eye. Such material is often called Tiger's Eye Matrix.
When cutting and polishing Tiger's Eye gemstones, skillful orientation to the fibrous structure must be applied to achieve the best chatoyancy. Ideally the cut should be perfectly parallel to the length of the fibers to achieve fullest chatoyancy. Cat's eye effect in Tiger's Eye do exist, but are uncommon in perfect form due to the wavy nature of the fibers.
USES
Tiger's Eye is a very inexpensive gemstone, and is used in beads for bracelets and necklaces, as well as in pendants. It is also used for costume jewelry and occasionally used for ornate carvings or floral pins. Gemstones cuts of Tiger's Eye are encountered but are not common.
Tiger's Eye TREATMENTS AND ENHANCEMENTS
Most Tiger's Eye is natural and not treated. Some of the red or maroon-toned Tiger's Eye is dyed to achieve that color.
Tiger's Eye SOURCES
The chief source of Tiger's Eye is South Africa, from the Northern Cape Province. Other, less important sources include Namibia, Australia, India, and Thailand. Although uncommon worldwide, the abundance of the deposits in South Africa are extensive enough to make Tiger's Eye very affordable.
SIMILAR GEMSTONES
Tiger's Eye is a very unique gemstone type and is not easily confused with any other gemstones.
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