Gilsonite (uintaite) [12002-43-6] is a natural hydrocarbon substance of the class known as asphaltites (see Asphalt), occurring as a coal-like solid which is mined much like other minerals and sold essentially in its native state. The only commercially important deposits of Gilsonite in the world are located in the Uinta Basin, in the northeast corner of Utah. From a point 6-8 km within Colorado (Rio Blanco County), the area involved extends westward about 100 km into Utah. Gilsonite occurs in veins varying in width from a few centimeters to 6 m. The veins are nearly vertical planes running in a northwest-southeast direction, and extending downward from the surface as much as 600 m. Individual veins are as long as 35 km. Elsewhere in the United Stares, minor deposits of a Gilsonite like material have been reported in Wheeler and Crook Counties of Oregon (1). Extended geological work in the Uinta Basin leaves little doubt that the source material was the tremendous oil shale deposits of the contiguous territory, which is further confirmed by certain similarities in the composition of the hydrocarbons involved, ie, both Gilsonite and shale oil have a nitrogen content much higher than petroleum oils in general (see Oil shale).

Classification of gilsonite

Gilsonite is classed as one of the asphaltites, which are natural asphalt like substances, characterized by their high softening points (above 110°C). Glance pitch and grahamite are other members of this group, some properties of which are shown in Table 1 (2). The nonmineral constituents are almost completely soluble in carbon disulfide. Solubilities in aromatic solvents are described in ref. 3.

Properties of Gilsonite

The tests applied to gilsonite are in many cases the same as those used for asphalt (qv). Typical properties of commercial-grade gilsonite (American Gilsonite Selects) are shown in Table 2. Gilsonite is a natural mineral, not a manufactured product, and is, therefore, subject to certain variations. The liquid distillate from the pyrolysis of solid gilsonite was treated with sulfuric acid to produce a nonreactive hydrocarbon fraction which was classified as paraffinic (5). Evidence for pyridines and quinolines in the distillate was apparently based on odor alone. There are several hydrocarbon fractions from gilsonite distillate with many properties similar to those of fractions from crude petroleum (6). Cycloparaffins (naphthenes) and olefins were identified as hydrocarbon types. Several phenols, pyrroles, and pyridines have been isolated in the pyrolytic distillate from gilsonite (7-8). A heavy yellow oil was obtained from undegraded gilsonite in yields of 4-8% (9). Several aromatic and nonaromatic cuts, the latter predominating, resulted from low pressure distillation and silica gel adsorption of the oil. Substituted naphthalenes were indicated in the aromatic fractions by uv spectra. Destructive distillation of gilsonite gave 12 wt % gases, 55 wt % of a liquid pyrolyzate, and 33 wt % coke. Porphyrin fractions were isolated from ores of two different veins in yields of 0.03 and 0.004% (eg, deoxyphylloerythreoetioporphyrin) (10). The entire porphyrin content is present as a nickel complex. The presence of porphyrins suggests that gilsonite is of plant origin (see Pyrrole and pyrrole derivatives).

Mining of gilsonite

Methods of mining have included the traditional hand pick, pneumatic picks, blasting, and high pressure (up to 13.8 MPa or 2000 psi) hydraulic cutting. All methods have been used concurrently in different mines with the choice depending upon mine conditions, and elevating and surface handling requirements.

Table I. Properties of Gilsonite, Glance Pitch, and Grahamite

Softening Point, Ring and Ball Method, °C

Specific Gravity at 25°C



Fixed Carbon*
Gilsonite or uintaite Glance pitch or manjak* grahamite**

Brown Black Black

1.03-1.10 1.10-1.15 1.15-1.20

132-190 132-190 188-329

10-20 20-35 35-55

* By proximate analysis, as for coal. ** When substantially free from mineral matter.

Table II. Properties of Gilsonite*



Color in Mass Color of Streak or Powder Fracture Specific Gravity, 15/15ºC Softening Point (Ring and Ball Method), ºC Bitumen Soluble in Carbon Tetrachloride, % Behavior in Petroleum SolventsFlash Point, COC**, ºC Heating Value, kJ/g*** Specific Heat, J/kg***

black brown conchoidal 1.04 160 99.8 liquid solution that may thicken slightly upon standing 315 41.8

at 149ºC at 260ºC

2180 2550

Thermal Coefficient of Expansion (Volumetric), per °C Viscosity (Brookfield Viscometer), mPa·s (= cP)


at 260ºC at 288ºC at 316ºC

500 250 140

Volatility (5 h), wt %
at 163ºC at 204ºC at 260ºC

<2 <4 <6

Volatile Combustible Matter, by ASTM D271-4 for VCM in coal, % Ultimate Analysis, wt %


Carbon Hydrogen Nitrogen Oxygen Sulfur Silicon, Nickel, and Trace Elements Solid Paraffins (Unsulfonated Residue)

85 10 2.5 1.5 0.3 0.2 0-trace

Hardness (Mohs Scale) Penetration, 100 g, 5 s, mm/10


at 25ºC at 46ºC at 66ºC at 77ºC

0 0 1 2

Resistivity, ·m Acid Value¹ Diazo Reaction² Saponifiable Matter Constituent Analysis, wt %³

1.9 X 10¹º 2.3 none trace

Asphaltenes Resins Oils

50-65 35-45 1-5

* American Gilsonite Selects. ** Cleveland open cup. *** To convert J to cal, divide by 4.184. ¹ mg KOH/g substance to give pH 7. ² Color reaction to determine presence of phenols. ³ Ref. 4.

Economic Aspects

Until the late 1950s when the American Gilsonite Company converted gilsonite into petrochemicals and conventional petroleum-type products, gilsonite markets, although worldwide in scope, were limited in volume to applications in which the gilsonite was dissolved in light solvents, or fluxed with vegetable oils and other hydrocarbons as heavy as petroleum asphalt. New and much larger applications began to develop for the unaltered product of the mines and it became obvious that conversion of gilsonite to fuels in competition with crude petroleum was a poor way to use this unusual natural resource. The total gilsonite market is now in excess of $20,000,000 annually with tonnage mined <25% of that formerly produced. The average selling price at the mine head is in the range of $170-180 per metric ton with prices increasing at about the United States inflation rate. About75% of the sales are within the United States. This change in gilsonite markets has led to long term availability and a more orderly utilization of this resource. At current price levels, minable reserves of gilsonite are estimated to be ca 5,000,000 t. Total reserves are probably in the range of 10,000,000-15,000,000 t.

Uses of gilsonite

Gilsonite is the raw material preferred by the Nuclear Power Commission in the UK for conversion to nuclear-grade graphite used in British designed advanced gas-cooled reactors. In early 1980 shipments of gilsonite commenced in volume to a United States petroleum refinery for conversion to a delayed type coke which, after calcining, is exported to the UK for graphitization and use in two AGR under construction at a cost of $36,000,000. Gilsonite is used by the automotive industry, principa1ly in the manufacture of solvent-free seam sealers, although there remains limited use in the production of paints and enamels. During the past eighty years gilsonite has been a principal ingredient in dark photogravure inks and, although lighter-colored inks are now more widely used, the market for gilsonite in the ink industry continues to increase (see Inks). Many applications for gilsonite, such as its use in battery boxes, floor tiles, molding compoundings and rubber products, have largely ceased to exist but large quantities now are used by the oil-drilling, foundry, building board, explosive and nuclear graphite industries, in addition to the continuing use by the automotive and ink industries. Bibliography “Gilsonite” in ECT 2nd ed., Vol. 10, pp. 527-533, by H. O. Erbin, American Gilsonite Co. 1. E. T. Hodge, Bull. Am. Assoc. Pet. Geol. 11, 395 (1927). 2. H. Abraham, Asphalts and Allied Substances, 6th ed., Vol. 1, D. Van Nostrand Co., Inc., Princeton, N.J., 1960, p. 229. 3. U.S. Pat. 4,108,681 (Aug. 22, 1978), M. B. Lawson and K. J. Snyder (to Halliburton Co.). 4. Ref. 2, Vol. IV, p. 366. 5. W. D. Day, J. Franklin Inst. 140, 221 (1895). 6. C. W. Mabey, J. Am. Chem Soc. 39, 2015 (1917). 7. R. E. Ruesser, An Investigation of the Organic Bases in Gilsonite, M.S. thesis, University of Utah, Salt Lake City, Utah, 1949. 8. J. M. Sugihara and D. F. Sorenson, J. Am. Chem. Soc. 77, 963 (1955). 9. T. F. McCullough, Hydrocarbons and Other Compounds Obtained from Gilsonite, Ph.D. thesis, University of Utah, Salt Lake City, Utah 1955. 10. L. R. McGee, Porphyrins in Gilsonite, Ph.D. thesis, University of Utah, Salt Lake City, Utah, 1956. General References “Gilsonite Cement,” Oil Gas J. 57(1), 150 (1959). A. Bezzant, The Chromatographic Separation of Gilsonite, thesis, Brigham Young University, Provo, Utah, 1949. G. A. Carey and I. C. Roberts, History, Occurrence, Mining and Economics of Gilsonite, thesis, University of Utah, Salt Lake City, Utah, 1949. A. L. Crawford, “Gilsonite and Related Hydrocarbons of the Uintah Basin, Utah,” The Oil and Gas Possibilities of Utah, Utah Geol. Mineral Surv., Salt Lake City, Utah, 1949, pp. 235-260. C. Davis, Geology of the Culmer Vein of Duchesne County, Utah, thesis, Brigham Young University, Provo, Utah, 1952. P. J. Grantham and A. G. Douglas, Adv. Org. Geochem, Proc. 7th Int. Meet., 1975, pp. 193-207. M. Inagaki, Y. Tamai, and S. Naka, Tanso 75, 118 (1973); Chem. Abstr. 82, 33141t (1975). U.S. Pat. 4,073,659 (Feb. 14, 1978), M. V. Burris. U.S. Pat. 4,133,932 (June 18, 1976), S. H. Peck (to USM Corp.). U.S. Pat. 4,086,195 (Apr. 25, 1978), W. R. Knox, J. C. Hill, L. J. Hughes, and P. W. Foerst (to Monsanto Co.). Can. Pat. 972,141 (Aug. 5, 1975), F. F. Sullivan (to Rotary Drilling Services, Inc.).