Gilsonite (Uintaite, Natural Asphalt)

Natural asphalt from the Uinta Basin, graded by softening point and ash

Gilsonite is a natural asphalt: a black, brittle, solid hydrocarbon, known to mineralogists as uintaite, that is mined rather than refined. It occurs as near-vertical veins in the Uinta Basin of north-eastern Utah, where Samuel Gilson had a mining company by 1888, and the name Gilsonite is a trademark registered in 1921 by American Gilsonite Company. The Utah Geological Survey has documented more than 170 miles of veins, estimates the original resource at about 45 million short tons and reports recent production of 60,000 to 80,000 short tons a year. What sets Utah material apart is purity. The producer's published figures are a specific gravity of 1.01 to 1.04, a softening point above 300 °F (about 149 °C), more than 99 per cent solubility in carbon disulphide, inorganic matter of 0.3 per cent and sulphur under 1 per cent. Grades are sold by softening point: above 325 °F (163 °C) and above 350 °F (177 °C) for oil-based drilling muds, and a high-temperature series at 400 to 500 °F (204 to 260 °C).

Not everything offered as gilsonite is that material. Natural bitumen and asphaltite from other countries, notably Iran, are sold under the same name and are graded by ash, with seller sheets at up to 5, 10 and 15 per cent ash against 0.3 per cent for Utah material; a buyer of drilling-fluid or ink grade should ask for ash, softening point and solubility on the certificate, not the name. Iranian-origin goods are subject to United States and other sanctions, and CBIL does not broker sanctioned-origin cargo. The uses divide four ways: fluid-loss control and lost-circulation material in drilling fluids and well cements, black printing inks, paints and stains, strengthening of paving bitumen, and an additive in foundry sand. Gilsonite is declared under HS 2714.90 with other natural asphalts and asphaltites; the United States declared about 90,000 tonnes of exports under that code in 2024 at a declared value of about USD 960 per tonne. CBIL brokers gilsonite between a named mine or producer and a named buyer, against a certificate of origin, the producer's certificate of analysis and SGS or Intertek inspection at loading for softening point, ash, moisture and mesh size, in lump or powder, bagged or in bulk bags by the container, on FOB, CFR and CIF terms. Send the use, the softening point and ash limits, the mesh size and the volume.

See also: Oxidized bitumen: the refined high-softening-point grades · Polymer modified bitumen · Bitumen paint

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Excluded origins are not offered, including product re-exported, blended or re-processed through a third country. Every lot moves with a certificate of origin naming the producing plant, mine or grower country, and nothing is quoted before the seller and loading point are known.