Gilsonite (uintaite) is found chiefly in the Uinta Basin of the United States, in a belt about 65 miles long extending from Rio Blanco County, Colorado, through Uintah County, Utah, into Duchesene County; most of the important deposits are in Utah (3,4,10). It occurs in vertical veins that vary in width from a few inches up to 22 feet, average 4 to 6 feet, and range in depth from 100 feet near the White River, on the eastern end of the belt, to about 2000 feet near Myton, Utah, on the western end, where it has been mined to a depth of 1500 feet (2). The veins contain almost no inorganic matter but are sandwiched between sheer sandstone walls and outcrop at ;the surface, where they may be traced for several miles in a general direction from southeast to northwest (1,10). About the turn of the century, it was estimated that these deposits contained nearly 50,000,000 tons, but more recent appraisal indicates approximately 30,000,000 tons, of which about 16,000,000 tons is considered suitable for commercial development (2). Figure 1 shows the location and direction of the veins (11).