Gilsonite, also known as “uintahite”, “asphaltum” or asphaltite, is a naturally occurring soluble solid hydrocarbon, a form of asphalt (or bitumen) with a relatively high melting temperature. Its large-scale production occurs in the Uintah Basin of Utah and Colorado, United States. Although the substance has been historically mined in the Uintah Basin, resources are being discovered and mined more recently in other countries such as Colombia and Iran. Gilsonite is mined in underground shafts and resembles shiny black obsidian.

Discovered in the 1860s, it was first marketed as a lacquer, electrical insulator, and waterproofing compound approximately 25 years later by Samuel H. Gilson.
Gilsonite is categorized as a soluble material in oil solutions such as CS2 or TCE (trichloroethylene). A major component of gilsonite is carbon; it also contains several other elements including nitrogen and sulfur and some volatile compounds.
Gilsonite reserves are distributed globally, especially within basins. It has also been found on the dwarf planet Ceres and is predicted to exist on the Martian moon Phobos.
Gilsonite is used in more than 160 products, primarily in dark-colored printing inks and paints, oil well drilling muds and cements, asphalt modifiers, foundry sand additives, and a wide variety of chemical products. The trademark, registered in 1921, belongs to the American Gilsonite Company which filed for bankruptcy and after accepting re-organization seems to emerge from it at Jan 3rd 2017.

A common application of gilsonite is in bitumen blending.
This application is practiced in countries such as China, India and Iran.