Tigereye (or tiger eye) is a richly striped variety of quartz with a fine luster. These semiprecious beads are available in their natural, unenhanced brown-gold state, and sometimes in heat-treated blue or red. Also known as African cat's eye, crocidolite, and tiger's eye, this gemstone contains oriented fibers of crocidolite (a mineral of the amphibole group) that have been replaced by silica. The fibers are twisted or crumpled instead of straight, reminiscent of sand and sunlight. Tigereye is also vitreous (hard, unbendable and glass-like). With its strong chatoyance, the gemstone gets its name from its resemblance to the eye of a tiger.