Footnote

a The terms bitumen, asphalt, tar, and pitch are often used interchangeably. However, bitumen is a generic term for a class of dark, heavy hydrocarbon compounds found in tar, pitch, and petroleum. Tar is a dark sticky substance obtained as a condensate from the destructive distillation of materials such as wood, coal, and peat. Further evaporation of tar yields pitch as a semisolid residue. Tar and pitch have a relatively low bitumen content.

Petroleum, or crude oil, when evaporated leaves a residue composed almost entirely of bitumen. Petroleum-derived bitumen is also called asphalt. However, in many places “asphalt” refers to bitumen mixed with mineral aggregates like sand or gravel, often used in the paving of roads. For the purpose of this article, “asphalt” refers to either the crude or the refined product from the Pitch Lake.