Chalcolithic
The Chalcolithic (greek chalkos + lithos, "copper stone") period, also known as the Eneolithic period, is a phase in the development of human culture in which the use of early metal tools coexists with the use of stone tools.The period is a transitional one outside of the traditional three-age system, and occurs between the neolithic and bronze age. It is apparently only distinguished by Archaeologists in some parts of the world, e.g., Europe and West and Central Asia.
Many Megaliths in Europe were erected during this period.