Tiger's Eye
Tiger's eye is a Quartz pseudomorph after the blue asbestos known as crocidolite. The iron from the decomposed crocidolite has oxidized to a brown colour, keeping the fibrous structure. The material exhibits a fascinating and constantly shifting light effect since the alternating silky gold and brown bands keep reversing their appearance with the slightest change in position of the light source or of the stone.
Recently Heaney and Fisher (2003) gave another interpretation of Tiger's eye origin: "..we argue that tiger's-eye classically exemplifies synchronous mineral growth through a crack-seal vein-filling process."
Recently Heaney and Fisher (2003) gave another interpretation of Tiger's eye origin: "..we argue that tiger's-eye classically exemplifies synchronous mineral growth through a crack-seal vein-filling process."
| General Information | ||||||
|---|---|---|---|---|---|---|
| A variety or type of: | Quartz | |||||
| Varieties/Types: | Falcon's Eye - Trade name for a blue variety of Tiger's Eye. | |||||
| Chemical Formula |
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| Tiger's Eye Treatments | ||||||
| May be bleached to lighten the color and dyed to any color. Also heat-treated to produce the dark red "Bull's eye" - Blue Chart Gem Identification, Herve Nicolas Lazzarelli, 2010, p 7 | ||||||
| Physical Properties of Tiger's Eye | ||||||
| Mohs Hardness | 6.5 to 7, Gemstones of the world (2001) More from other references | |||||
| Specific Gravity | 2.58 to 2.64, Gemstones of the world (2001) More from other references | |||||
| Cleavage Quality | None, Gemstones (2009) | |||||
| Fracture | Conchoidal, Gems, Sixth Edition (2006) | |||||
| Optical Properties of Tiger's Eye | ||||||
| Refractive Index | 1.534 to 1.540, Gemstones of the world (2001) More from other references | |||||
| Optical Character | Uniaxial/+, Gemmological Tables (2004) | |||||
| Birefringence | None, Gemstones of the world (2001) | |||||
| Pleochroism | Absent, Gemstones of the world (2001) | |||||
| Dispersion | None, Gemstones of the world (2001) | |||||
| Chatoyancy | Chatoyant, Blue Chart Gem Identification (2010) | |||||
| Colour | ||||||
| Colour (General) | Gold-yellow, gold-brown, Gemstones of the world (2001) More from other references | |||||
| Transparency | Opaque, Gemstones of the world (2001) More from other references | |||||
| Lustre | Vitreous, Management Team (2012) | |||||
| Fluorescence & other light emissions | ||||||
| Fluorescence (General) | None, Gemstones of the world (2001) | |||||
| Crystallography of Tiger's Eye | ||||||
| Crystal System | Trigonal, Management Team (2012) | |||||
| Habit | Fibrous aggregate, Gemstones of the world (2001) | |||||
| Further Information | ||||||
| Mineral information: | Tiger's Eye information at mindat.org | |||||