Bitumen

Mixture of hydrocarbons that naturally form a viscous paste.

There were several sources of bitumen in Mesopotamia, including around Hit on the middle Euphrates. Bitumen was widely used by the Mesopotamians for waterproofing or caulking pipes, terraces and boats, glue notably to make tools, and black paint to decorate buildings or objects. Bituminous limestone impregnated with hydrocarbons from Lower Mesopotamia was used for sculpture. It was soft and easy to work but resembled hard stones such as diorite and basalt.