Geochemical exploration for Gilsonite

The gilsonite and ozokerite deposits of the Unita Basin, Utah, were investigated geochemically. Soil samples were collected along traverses across productive veins in several areas. These soil samples were analysed for gilsonite and ozokerite. The gilsonite and ozokerite content of the soil samples was related to vein proximity. The veins investigated were the Cowboy vein, the Chepetta lode, the Carbon lode, the Rainbow vein, the Pariette vein, and the Soldier Summit ozokerite deposit. Three laboratory procedures were developed to separate gilsonite from the soil samples. All were based on the difference in specific gravity between gilsonite, which has a specific gravity of 1.04, and soil fraction, which has a specific gravity of about 2.0 - 2.6. In one procedure tetrabromoethane in benzene was the heavy liquid medium. In the other procedure carbon tetrachloride was the heavy liquid medium. In each of these procedures, the gilsonite was floated. In the third procedure, the gilsonite was separated from the soil by panning. In each procedure the gilsonite fraction was weighed, and the gilsonite content of each sample was expressed as parts gilsonite per million parts of sample by weight. The precision of the procedures was determined by replicate analyses. The standard deviation of the derived result in the calculation for PPM gilsonite is +-16.6%. Geochemical anomalies were recognized in each instance. Background values ranged from 200 PPM to 1,000 PPM. Anomalies ranged from 2,910 PPM to 264,000 PPM, and the contrast raged from 16 t0 545. In addition to geochemical anomalies disclosed over each vein, several anomalies at a distance from known veins were observed. These anomalies may reflect covered veins. Gilsonite content and dispersion halos surrounding the veins are due to weathering and erosion of gilsonite veins.