tiger 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.