Tiger's eye

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Tiger's eye (also Tigers eye, Tiger eye) is a chatoyant gemstone that is usually yellow- to red-brown, with a silky luster. It is a fibrous silicified crocidolite (blue asbestos), a classic example of pseudomorphous replacement. An incompletely silicified blue variant is called Hawk's eye. A member of the quartz group, its physical and optical properties are identical or very near to those of single-crystal quartz.

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 fibreoptic glass is a common imitation of tiger's eye, and is produced in a wide range of colours.

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.^[1] Formed by the alteration of crocidolite and consists essentially of quartz colored by iron oxide. Origin: South Africa

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

References

1. ^ http://ist-socrates.berkeley.edu/~eps2/wisc/sg.html Berkeley.edu

• GSA Comment and Reply on formation of Tiger's and Hawk's Eye