GILSONITE, an asphaltite found in eastern Utah and western Colorado mainly in the Uinta Basin (whence its alternative names, Uintahite or Uintaite), where it occurs in vertical veins up to i8ft. in thickness which can be traced for several miles. It is black in colour with conchoidal fracture and lustrous surface, and was so named after S. H. Gilson of Salt Lake City. On heating it softens and then fuses completely; it dissolves freely in carbon disulphide, and is largely used in the manufacture of paints and varnishes. The output from the Uinta Basin region is about 20,000 tons annually.