The Copper Age, also called the Eneolithic or the Chalcolithic Age, has been traditionally understood as a transitional period between the Neolithic and the Bronze Age, in which a gradual introduction of the metal (native copper) took place, while stone was still the main resource utilized. Recent archaeology has found that the metal was not introduced so gradually and that this entailed significant social changes, such as developments in the type of habitation (larger villages, launching of fortifications), long-distance trade, and copper metallurgy.
Roughly, the Copper Age could be situated chronologically between the 5th and 6th millennia BCE in places like the archaeological sites of Majdanpek, Јarmovac and Pločnik (a copper axe from 5500 BCE belonging to the Vinča culture). Somewhat later, in the 5th millennium BCE, metalwork is attested at Rudna Glava mine in Serbia, and at Ai Bunar mine in Bulgaria.
3rd millennium BCE copper metalwork is attested in places like Palmela (Portugal), Cortes (Navarre), and Stonehenge (England). However, as often happens with the prehistoric times, the limits of the age cannot be clearly defined and vary between different sources. 
The Earliest Copper Mining Europe: (Vinca Culture, c. 5,000 BC).
The early Neolithic mine of Rudna Glava near Majdanpek is an example of the oldest known technology of Vinca copper working. The developed skills of the Rudna Glava miners are indicated by the ore-emptied shafts no less than 20m deep.
Stone mallets, made from river stones of volcanic rock, gives evidence of the higher specialization of primitive tools for different and various productive purposes. As for the chopping of the pieces different types of wedges were used, while the tools made from deer horns were used for gathering the ore already chopped.
When an ore vein was discovered, the access platform was built round its flooding canal. Afterwards the hard ore mass was broken into pieces by circular hits with stone mallets, hanged either on a rope or leather belt. In the depths, the technique of heating then cooling suddenly was used. Large ceramic dishes were used for pouring the water over the hot ore blocks. Cracked blocks were further smashed and broken into pieces.
The ore obtained was taken to the surface in bags, and it was distributed to the settlements near by. Further metallurgic processes are considered to be a part of technological circle of handworks in that early period of metal usage. (Full Article: http://www.muzej-mpek.org.yu/e_rglava.htm)
Metsamor (Medzamor), Armenia - Metsamor has revealed foundries that were processing metal as far back as 5,000 BC. The site contains the oldest large-scale metallurgical factory in the world (2,500 BC). Discovered by Dr Koriun Megatchian, in Soviet Armenia (20Km from Ararat). It contained over 200 furnaces, producing an assortment of vases, knives, spearheads, rings, bracelets, etc.
The Metsamor craftsmen wore mouth-filters and gloves while they laboured and fashioned their wares of copper, lead, zinc, iron, gold, tin, manganese and fourteen kinds of bronze. The smelters also produced an assortment of metal paints, ceramics and glass. But the most out-of-place discovery was several pairs of tweezers made of steel, taken from layers dating back before the first millennium BC. The steel was later found to be of exceptionally high grade, and the discovery was verified by scientific organizations in the Soviet Union, the United States, Britain, France and Germany. (9)
The Great Ancient Copper Mines of Michigan
It is estimated that half a billion pounds (Ref.1) of copper were mined in tens of thousands of pits on Isle Royale and the Keweenaw Peninsula of Michigan by ancient miners over a period of a thousand years. Carbon dating of wood timbers in the pits has dated the mining to start about 2450 BC and end abruptly at 1200 BC. Officially, no one knows where the Michigan copper went. All the “ancient copper culture” tools that have been found could have been manufactured from just one of the large boulders. A placard in London’s British Museum Bronze Age axe exhibit says: “from about 2500 BC, the use of copper, formerly limited to parts of Southern Europe, suddenly swept through the rest of the Continent”. No one seems to know where the copper in Europe came from.
Indian legends tell the mining was done by fair-haired “marine men”. Along with wooden tools, and stone hammers, a walrus-skin bag has been found (Ref.1). A huge copper boulder was found in the bottom of a deep pit raised up on solid oak timbers, still preserved in the anaerobic conditions for more than 3,000 years. Some habitation sites and garden beds have been found and studied (various ref.). It is thought that most of the miners retired to Aztalan (near Madison, Wisconsin) and other locations to the south at the onset of the hard winters on Lake Superior. The mining appears to have ended overnight, as though they had left for the day, and never came back.
During this thousand-year period of mining, some of the miners must have explored the continent to the west, as evidenced by strangely large skeletons in a lot of places, such as the red-haired giants who came by boat to Lovelock Cave on Lake Lahontan (Nevada), that were found in 1924 with fishnets and duck decoys (Ref.77). There is “biological tracer” evidence for foot traffic back and forth across the continent, more that three thousand years before the Lewis and Clark Expedition. Huber (Ref.27) describes the “remarkable” presence of the shrub Devil’s Club on Blake Point, the northern tip of Isle Royale, and on Passage Island, offshore, and also on small islands around Rock Harbor, on Isle Royale. Its usual habitat is the rainforest gullies of the conifer forests of the Pacific Northwest. Huber claims it appears nowhere else east of the Rocky Mountains. This plant has giant leaves, with spines underneath, and frightfully spiny woody stems. It has a history of traditional use as a medicine, to treat diabetes, tumors, and tuberculosis, with its effectiveness confirmed by modern studies. It appears likely it was carried in a medicine bag to this remote island in Lake Superior in ancient times, and the places where the Devil’s Club are found are showing us where the miners were using medicines.
Silver in the Copper
Pieces of the “native” Michigan copper sometimes have crystals of silver inclusions, mechanically enclosed but not alloyed; this is called “halfbreed copper”. In the commercial mines, the miners are said to have cut these silver nodules off with knives, and take them home. The presence of silver nodules in “Old Copper Culture” tools shows they were made by hammering, called “cold working”. These hammered weapons and tools found in Hopewell mounds sometimes “show specks of silver, found only in copper of Lake Superior” (Ref. 69). Apparently, one instance of identification by silver inclusion has occurred overseas: In this letter of December 1st, 1995, Palden Jenkins, a historian from Glastonbury, writes, “I met the farmer who owns the land on which a megalithic stone circle is, called Merry Maidens, in far west Cornwall. While clearing hedges, he discovered an arrowhead, which was sent to the British Museum for identification. The answer returned: ‘5,000 years old; source, Michigan, USA’.” (Ref.76).
Trace Element Analysis
The temperature of a wood fire is 900°C, and with charcoal above 1000°C, but forced air fires are hotter, and met the need to obtain the 1084°C melting point of copper. The melting of crystallized copper, and pouring it into oxhide molds (the shape of the skin of a flayed ox) for shipping, wherever it was done, is the first step in its contamination. Re-melting, for pouring into tool molds, can involve the use of fluxes, fuel contamination, the addition of used/broken tools, and the addition of arsenic or tin.
Since metals always contain small portions of trace elements, it was thought we could follow the copper, by looking at trace elements in copper elsewhere, to see if it matched. The six early studies reported by Griffin (Ref.25), all report native copper at 99.92% copper. Rapp and others (Ref.8,53) report that using trace element “fingerprints”, using mostly Lake Superior copper samples, probable geographic/geologic source identification can be done. The work of Hancock et al. (Ref.47) showed again that native copper, including Michigan copper, showed lower levels of tin, arsenic, gold, and especially cobalt, than “European copper” manufactured artifacts. The British Museum reported “generally low trace element content [in] our Egyptian artifacts” (Ref.2). Years ago, the author collected some European copper and bronze axes, thinking that he might do some sampling of them for some commercially-available trace element analysis. Unfortunately, sample testing is only useful for hammered copper tools, not melted/cast ones. Looking at artifacts, full of mixed contaminants in their manufacturing, has for the most part, not been helpful. We need to look at the least-disturbed samples, the ingot form in which copper was shipped.. .
much more on this subject later.