Chemistry has become an efficient instrument of archaeological research. Its main contribution is the precise definition of materials. On different examples of recent research projects, it is shown that a correct description of a material gives valuable information on the provenance and the age of a historical object, but also on the social, economical, and political situation at the period of its manufacture. As an example of this experience it is shown that the general term, bronze, has to be replaced by about 25 or more precise terms which define precisely the type of alloy. The same with chemical analysis giving information on the technique of manufacture. They too allow to describe more precisely the historical situation at the time, when an archaeological object was made.