Emily Dickinson Lexicon

JET, n.¹ [D. git; Fr. jayet; L. gagates.]

A solid, dry, black, inflammable fossil substance, harder than asphalt, susceptible of a good polish, and glossy in its fracture, which is conchoidal or undulating. It is found not in strata or continued masses, but in unconnected heaps. It is wrought into toys, buttons, mourning jewels, &c. – Nicholson. Encyc. Jet is regarded as a variety of lignite, or coal originating in wood. – Haüy. Cleaveland.