Kobberalderen eller æneolitikum er en periode mellem stenalder og bronzealder i bl.a. Egypten og store dele af Europa, men ikke i Danmark.
- Susan R. Martin 1995. The Michigan Archaeologist 41(2-3):119-138: The State of Our Knowledge About Ancient Copper Mining in Michigan Citat: "...responsible for the prehistoric copper exploitation of Michigan, is...American Indians...duration of prehistoric mining...about seven thousand years ago to protohistoric times..."
- History & Archaeology Page II Citat: "...Whether ancient Turkey entered the Chalcolithic in 5000 BC or 5500 BC (or even 6000 BC) depends on whether the author is a native Turk or not. In Israel, the period lasted from 4500 till 3500, in Akkadia from 4000 to 3500, in central India (Balathal) from 2500 to 1500, and in Cyprus, the greatest of all Classical copper suppliers, it had to wait till coppersmiths from Asia Minor migrated there in about 3500 BC...copper mines in Arak, Hamadan, and Sialk, Mesopotamia's other sources for copper were at Tabriz, Diyurbakir, Kulteppe and Erzincan...mountain ranges involved are the Ak Dag Mountains to the north of Babylon and the Zagros foothills in Armenia..."