uintaite

A natural black bitumen used in the manufacture of acid, alkali, and waterproof coatings.

Gilsonite; a black, brilliant, and lustrous variety of bitumen giving a dark-brown streak, breaking with a beautiful conchoidal fracture, and having a hardness of from 2 to 2.5 and a specific gravity of from 1.065 to 1.07. It is easily fusible, dissolves in turpentine, and is used in making varnishes and in coverings for electric insulation.