Descriptive term rather than the name of a specific material that in the West refers to two silicate minerals, nephrite and jadeite, which are notable for their hardness, toughness and attractive appearance when worked into a variety of objects. Green is the colour usually associated with jade but many other colours are known. The Chinese term yu refers not only to jade but also to softer stones such as serpentine, steatite, pyrophyllite, muscovite, olivine and sillimanite; all these minerals have been identified among early Chinese ‘jades’. Other minerals exist that resemble jade to a certain degree such as idocrase, grossular, amazonite and chrysoprase. Also, nephrite and jadeite are not simple minerals: other minerals are often included within their structure.