gilsonite

Gilsonite is a natural, resinous, hydrocarbon ore. This "natural asphalt" or "natural bitumen" is similar to hard petroleum asphalt; in mass it is a shiny, black substance, similar in appearance to the mineral Obsidian. This unique mineral 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