Jet
a dense variety of lignite passing by degrees of quality into bituminous fossil wood, sometimes perfectly black, capable of being easily cut and carved, and of receiving a very beautiful polish.
It takes its name from Gagas or Gages, a place in Asia Minor, where, according to Pliny, the substance was obtained, whence in his time it was called gagates, afterward corrupted into gagat, the modern German name, and jet. As a material for mourning ornaments jet is admirably adapted, and for that purpose is largely used.