Compendium

Tiger's eye is a gemstone of the quartz group with a silky, shifting sheen, known as chatoyancy, and colours running from gold to reddish brown. Wikipedia explains that the sheen comes from quartz grown in parallel with altered amphibole fibres, most of them turned to limonite, and that the stone is chiefly silicon dioxide tinted by iron oxide; Cunningham, in his entry on asbestos, says that fibrous mineral, polished together with quartz, is what is called tiger's eye. Its sources include South Africa, Namibia, India, Australia, Myanmar and the United States, among others, and is generally shaped as a domed cabochon to show off its sheen. Wikipedia records a belief that it wards off the evil eye, and that Roman soldiers wore it engraved to keep them safe in battle, a story Cunningham also tells. Cunningham places it under the Sun and the element of fire and uses it in money spells, to guard against danger, and to build courage, confidence and firm conviction; he also suggests gazing into its flashes in sunlight to look into the future. Hall describes a banded, slightly shiny stone, usually small and tumbled, and associates it with grounding spiritual energy, psychic abilities, protection against ill wishing and curses, clarity of intention and manifesting the will.