The mineral phase can be either:

• continuous: this is porous rock, usually calcareous, which is deeply impregnated with hydracarbon binder. It is known as asphaltic rock and, once crushed, produces asphalt (an example is the mines at Saint Jean de Maruéjois in the French Département of Gard).

• or dispersed: this is natural bitumen in which the minerals take the form of a powder dispersed in the binder. The mineral content is highly variable. Examples are Mesopotamian bitimuen and Trinidad Lake Asphalt.

These are known as NATURAL binders as they are found in the natural state, often in combination with mineral materials.

They have been known and used since very ancient times.