Tiger's Eye

Tiger's eye (also Tigers eye, Tiger eye) is a chatoyant gemstone that is usually yellow- to red-brown, with a silky luster. A member of the quartz group, it is a classic example of pseudomorphous replacement by silica of fibrous crocidolite (blue asbestos). An incompletely silicified blue variant is called "Hawk's eye".

The gems are usually cut en cabochon in order to best display their chatoyancy. Red stones are brought about through gentle heat treatment. Honey-coloured stones have been used to imitate the much higher valued cat's eye chrysoberyl (cymophane), but the overall effect is unconvincing. Artificial fiberoptic glass is a common imitation of tiger's eye, and is produced in a wide range of colors. Tiger's Eye mostly comes from South Africa.

Tiger iron is an altered rock composed chiefly of tiger's eye, red jasper and black hematite. The undulating, contrasting bands of colour and luster make for an attractive motif, and it is mainly used for jewelry-making and ornamentation. Tiger iron is a popular ornamental material used in a variety of applications, from beads and cabochons to knife hilts. Along with tiger's eye it is mined primarily in South Africa and Western Australia. Tiger's eye is primarily composed of silicon dioxide (SiO₂) and the specific gravity ranges from 2.64 -2.71. [http://ist-socrates.berkeley.edu/~eps2/wisc/sg.html Berkeley.edu] Formed by the alteration of crocidolite and consists essentially of quartz colored by iron oxide. Origin: South Africa and Australia

Notable sources of tiger's eye include the USA, South Africa, Canada, China, Brazil, Namibia, India and Burma.

References

* [http://lists.allenpress.com/GSA/i0091-7613-31-6-e44.pdf GSA Comment and Reply on formation of Tiger's and Hawk's Eye]