The period is a transitional one outside of the traditional three-age system, and occurs between the Neolithic and Bronze Age. It appears that copper was not widely exploited at first and that efforts in alloying it with tin and other metals began quite soon, making distinguishing the distinct Chalcolithic cultures and periods difficult.
The emergence of metallurgy occurred first in the Fertile Crescent, where it gave rise to the Bronze Age in the 4th millennium BC. There was an independent and limited invention of metallurgy in pre-Columbian Mesoamerica form about the 7th century CE, which however didn't go past the "Chalcolithic" stage.
The literature of European archaeology generally avoids the use of 'chalcolithic' (they prefer the term 'Copper Age'), while Middle-Eastern archaeologists regularly use it. The Copper Age in the Middle East and the Caucasus begins in the late 5th millennium BC and lasts for about a millennium before it gives rise to the Early Bronze Age. Transition from the European Copper Age to Bronze Age Europe occurs about a millennium later, between the late 4th and the late 3rd millennia BC.
According to Parpola, ceramic similarities between the Indus Civilization, southern Turkmenistan and northern Iran during 4300–3300 BC of the Chalcolithic period (Copper Age) suggest considerable mobility and trade.
The European Beaker people are often considered Chalcolithic as were the cultures which first adopted urbanisation in southwest Asia. Many megaliths in Europe were erected during this period and it has been suggested that Proto-Indo-European linguistic unity dates to around the same time. Examples of Chalcolithic cultures in Europe include Los Millares on the Iberian Peninsula in present day Spain.
Ötzi the Iceman, found in the Ötztaler Alps and whose remains have been dated to about 3300 BC, carried a copper axe and flint knife. The high concentrations of copper found in his hair have lead to speculation that he was a metalworker, who may have died while prospecting for ore in the mountains.
The Neolithic-Copper Age Transition on the Great Hungarian Plain: Recent Excavations at the Tiszapolgar Culture Settlement of Veszto-Bikeri
Sep 01, 2002; The causes of the various social changes that occurred during the Neolithic-Copper Age transition in central-eastern Europe have...