JET (Fr. jais, Ger. Gagat), a substance which seems to be a peculiar kind of lignite or anthracite; often cut and polished for ornaments. The word “jet” probably comes, through O. Fr. jaiet, from the classical gagates, a word which was derived, according to Pliny, from Gagas, in Lycia, where jet, or a similar substance, was originally found. Jet was used in Britain in prehistoric times; many round barrows of the Bronze age have yielded jet beads, buttons, rings, armlets and other ornaments. The abundance of jet in Britain is alluded to by Caius Julius Solinus (fl. 3rd century) and jet ornaments are found with Roman relics in Britain. Probably the supply was obtained from the coast of Yorkshire, especially near Whitby, where nodules of jet were formerly picked up on the shore. Caedmon refers to this jet, and at a later date it was used for rosary beads by the monks of Whitby Abbey.