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A Brief History of Copper
(Released October 2005)

 
  by Marianne Stanczak  

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ankh
It represents Venus, both the planet and the goddess. It is the universal symbol for female (♀), and in hieroglyphics is represented by the ankh, which symbolizes eternal life. It is associated with Friday, the goddess Aphrodite and the country of Cyprus, where the word cuprum originates. Atomic number 29 on the periodic table, it has a melting point of 1083o C (1981.4o F) and a boiling point of 2567o C (4652.6o F). It is copper.

Copper is created in volcanic areas high in concentrations of hot sulfuric solutions. While copper is found worldwide, 90% of reserves are located in four areas: the Great Basin of the western United States, Zambia, central Canada, and the Andes regions of Peru and Chile. Antarctica too has copper ore deposits in many locations, but a moratorium on mining was established in 1991 to last for 50 years to preserve the vast land. To obtain the rare, pure copper requires smelting, leaching, or electrolysis. The most familiar forms of copper are pure copper, brasses (copper-zinc alloys) and bronze (copper-tin alloys). Found in nature mostly in impure mineral form (e.g. azurite, malachite, chalcopyrite, copper can also be produced by a biochemical process using the bacteriumThiobacillus ferrooxidans.

No one knows exactly when copper was first discovered, but earliest estimates place this event around 9000 B.C. in the Middle East. Present-day Israel, Egypt and Jordan were some of the earliest locations of copper smelting sites, dating back to about 4500 B.C. Located in southern Jordan, 30 miles south of the Dead Sea, the 70-room, 5000-year old Kirbat Hamra Ifdan foundry housed such copper artifacts as hammers and axes. Investment casting was realized in 4500-4000 B.C. in SE Asia (4000 B.C. in Thailand) and 3000 B.C. in Turkey. In India, artisans created copper alloy products such as icons and lamps. An Iron Age smelting site, Agia Varvara-Almyras, in Cyprus, had its complete operations recorded in written documents, which has contributed to much of our knowledge of ancient techniques. Metallurgical processes with copper alloys, most notably brass and bronze, were performed soon after an area's discovery of pure copper. The Egyptians had found that adding tin produce bronze makes casting easier, and they realized that an alloyed object is harder than copper alone. Tempering of copper was most likely discovered by accident, as was its malleability. Arsenic bronze objects were created in the Black Sea/North Caucasus area using the lost wax process.

One of the more amazing historical uses for copper, illustrating its staying power, was the copper tubing in ancient Egypt. It appeared to be constructed like today's plumbing fixtures. Found in the tombs and temples of rulers, much of this tubing remains in an excellent, even functional, state more than 5000 years after its first use. This is because the very malleable copper is not as susceptible to corrosion as other metals, which is why it is still used today for pipes. Unlike plastic, copper does not give off fumes, melt, or burn. In addition, copper has antibacterial properties that help to ward off microorganisms like those that cause Legionnaire's disease.

Further east, events and technology were progressing rapidly. Copper metallurgical processing was extensive, especially in China during Beijing's Yan Culture (approximately 2000-3000 years ago). Designs for casting furnaces were advancing quickly, especially in Luoyang China's western Zhou Dynasty. Overall, bronze culture in the East developed gradually over a period of 2000 years. Tin bronze work commenced from about the beginning of the 2nd millennium B.C. to the mid 1st millennium B.C. in Xinjiang, China. Xianjing helped to pioneer the smelting of copper sulfide ores and arsenical copper; it was the only site in Eurasia to add arsenic ores to its processes. The Far East, too, realized the advantage of using copper alloys by the Eastern Zhou period. Hydrometallurgy also began in China.

Buddha in temple
China's debut into copper metallurgy benefited other countries. The lead for Japan's production of bronze (~ 2nd century B.C.) came from China, but Japan added its own contributions. Mining and smelting were prevalent in the period between the 8th and 10th centuries, at the beginning of which the Japanese added iron oxide to improve the smelting process. The famous Nara Buddha was made with copper from the Naganbori mine. Bronze became important in Thailand, where a mining complex from 2000 B.C. was located in Phu Lon on the Mekong River. Ancient Koreans utilized smelting for copper processing and used a range of heat treatment temperatures.

Oetzi
"Oetzi": (top) a re-creation of his appearance (bottom) the 5000-year old mummy
http://www.preidlhof.it/deutsch/oetzi.htm
The technology of the Far East laid the foundation for that of Europe. As early as the Iron Age, bronze objects such as bracelets were being made for the necropolis of Chiavari, Italy. Three-thousand-year old German artifacts have been discovered. A 5000-year-old mummified man know as "Oetzti," found in the Alps on the Italian-Austrian border along with a copper arsenic axe, is one of the more interesting European discoveries. "Oetzti" is presumed to have been a coppersmith because of high concentrations of copper and arsenic found in his hair.

Other discoveries mark the progress of copper technology. Perhaps one of the more famous copper mines was the 4000-year old Great Orme, on the north coast of Wales. It contained chalcopyrite, malachite, and azurite. In Llandudno, Gwynedd, the Great Orme had an area of at least 24,000 square meters with five kilometers of passages 70 meters deep. Britain's first use of brass occurred some time around the 3rd - 2nd century B.C. The 1630s were the beginnings for Russia's first smelting plant in Pyskorsk. The Norddeutsche Affinerie in Hamburg was the first modern electroplating plant. In the 18th century Ural area, the region's first metallurgical plants were built. Evidence of Bronze Age sulfide ore smelting was found in Slovenia and uncovered the use of speiss ingots.

Although Europe seemed to make slow progress in copper metallurgy compared to Asia and the Middle East, many important technologies came from this continent. Flash smelting, which is still used today, was developed in order to make the smelting process more energy efficient. In 1908, in Outokumpu, Finland, a large deposit of copper ore was discovered, which eventually led to the development of flash smelting. Over the course of centuries, experience with copper has assisted the development of other metals; for example, knowledge of copper smelting led to the discovery of iron smelting.

Copper technology proceeded at a much slower rate on other continents. Africa's major location for copper reserves is Zambia. Copper burial ornamentals dated from the 15th century have been uncovered, but the metal's commercial production did not start until the early 1900s. Australian copper artifacts exist, but they appear only after the arrival of the Europeans; the aboriginal culture apparently did not develop their own metallurgical skills.

On the other side of the world, copper metallurgy was flourishing in South America, particularly in Peru around the beginning of the first millennium AD. Ceremonial and ornamental objects show the use of hammering and annealing. Copper was most commonly alloyed with gold and silver during the time when the Mayans, Incans, and Aztecs reigned in Central and South America.

Since the Europeans arrived in North America relatively late in historical world events, it might be assumed that metallurgy did not take place earlier. However, Native Americans, in the area between what is now Washington and Alaska, made ceremonial knives and daggers known as "coppers". A copper workshop was found at the Cahokia Mounds State Historic Site (East St. Louis, Illinois) that has been dated to about A.D.1100. It is not certain who operated this workshop, but archaeologists have referred to the craftspeople as Mississippians. The 17th century Illinois tribe took European copper objects and transformed them into jewelry and other objects to better suit their own cultural ideas. Copper and brass were also prevalent in early 17th century Ontario, Canada.

As we have seen, alloying to make brass or bronze was realized soon after the discovery of copper itself. Plating was another technology that began early, starting in the mid 1600s in some areas. One common use for copper plating, widespread in the 1700s, was the sheathing of ships' hulls. Copper sheathing could be used to protect wooden hulled ships from algae, and from the shipworm "toredo" (which is not actually a worm but a mollusk). The ships of Christopher Columbus were among the earliest to have this protection.

In the early 1800s, it was discovered that copper wire could be used as an insulator, but it wasn't until 1990 that copper, in oxide form, was discovered for use as a superconducting material. The German scientist Osann invented powder metallurgy of copper in 1830 while determining the metal's atomic weight. It was also discovered that the amount and type of alloying element (e.g. tin) would affect the tones of bells, allowing for a variety of rich sounds, leading to bell casting, another common use for copper and its alloys.

Crucial in the metallurgical and technological worlds, copper has also played an important cultural role, particularly in currency.

Coin with Constantine head
Bronze coin from the time of
Constantine the Great (A.D. 323 or 324)
http://www.moonmoth.demon.co.
uk/holed_coins.html
Italians in the 6th through 3rd centuries B.C. used copper lumps as money. At first, just the copper itself was valued, but gradually the shape and look of the copper became more important. Julius Caesar had his own coins, made from a copper-zinc alloy, while Octavianus's (Augustus Caesar's) coins were made from Cu-Pb-Sn alloys. American Indians, too, found value in copper. The Powhatan tribe risked danger by transporting it through enemy territory of the Monacan tribe. Once John Smith and the European colonists arrived, the Powhatans were able to trade their corn for the colonists' copper, allowing the Powhatans to obtain their currency in a less dangerous manner. Originally, the U.S. penny was made entirely of copper, but shortages during WWII forced the U.S. Mint to change its composition. In 1943, they minted a penny made of zinc-coated steel called a "white penny". By the end of 1943, spent shells (cartridge brass) from weapons factories became available in mass quantities to make a brass penny. After the end of the war, enough spent shells were available to produce five billion pennies.

Throughout history, copper's use in art has extended far beyond currency. Vannoccio Biringuccio, Giorgio Vasari and Benvenuto Cellini are three Renaissance sculptors from the mid 1500s, notable for their work with bronze.

From about 1560 to about 1775, thin sheets of copper were commonly used as a canvas for paintings.

grand wedding in heaven
Wedding of Peleus and Thetis, Joachim Wtewael
Source: http://www.phxart.org/pastexhibitions/copper.asp

A belief that metallic compositions were divine kept secret the exact compositions of India's distortion-free bronze mirrors. The gates of the Temple of Jerusalem used Corinthian bronze made by depletion gilding. Corinthian bronze was most prevalent in Alexandria, where alchemy is thought to have begun. Silver plated copper was used in the pre-photograph known as the daguerreotype. The Statue of Liberty, dedicated on October 28, 1886, was constructed of copper thought to have come from French-owned mines in Norway. Copper was important in African countries like Zaire, with the copper masks of the allegedly cannibalistic Sala Mpasu symbolizing power and chieftainship. In ancient India (before 1000 B.C.), copper was used in the holistic medical science Ayurveda for surgical instruments and other medical equipment. Ancient Egyptians (~2400 B.C.) used copper for sterilizing wounds and drinking water, and as time passed, (~1500 B.C.) for headaches, burns, and itching. Hippocrates (~400 B.C.) used copper to treat leg ulcers associated with varicose veins. Ancient Aztecs fought sore throats by gargling with copper mixtures. And today, many arthritis sufferers wear copper bracelets to relieve pain.

Copper has been pivotal in the economic and sociological worlds, notably disputes involving copper mines. The 1906 Cananea Strike in Mexico dealt with issues of work organization. The Teniente copper mine (1904-1951) raised political issues about capitalism and class structure. Japan's largest copper mine, the Ashio mine, was the site of a riot in 1907. The Arizona miners' strike of 1938 dealt with American labor issues including the "right to strike". One copper mine, in Sumsbury, Connecticut, even became a prison during the American Revolution. It housed the Tories, those still loyal to Britain.

The Baghdad Battery
Copper is also the part of many rich stories and legends, such as that of Iraq's "Baghdad Battery." Copper cylinders soldered to lead, which date back to 248 B.C. to 226 A.D, resemble a galvanic cell, leading people to believe this may have been the first battery. This claim has so far not been substantiated.

The Bible also refers to the importance of copper: "Men know how to mine silver and refine gold, to dig iron from the earth and melt copper from stone" (Job. 28:1-2). The mythical King Solomon's Mines in Timna, Israel, held black copper, which had to be refined in order to rid the metal of impurities. King's Solomon's Temple (~1000 B.C.) contained the so-called "Bronze Sea"—a 16,000-gallon tank, perhaps for water, held up by 12 bronze bulls. Perhaps the most intriguing use of copper occurs in the Copper Scroll, part of the mysterious Dead Sea Scrolls found in Qumran in 1952. The Copper Scroll consists of thin rolled copper sheets that had to be carefully cut open because the oxidized metal made it difficult to unroll. Basically a treasure map, it leads the way to vast hidden riches, including gold and silver. The treasure has yet to be found. Many of these discoveries could not be possible without the help of a little bit of botany. Through phytoarchaeology, metal-tolerant plants help to identify ore bodies and mining and smelting sites. For example, Haumaniastrum katangense, the African Copper Flower, is found only in soils rich in copper or cobalt and has helped the discovery of mines and smelting areas from 14th century Zaire. Other examples of copper-tolerant plants include Minuartia verna (vernal sandwort) and Armeria martima (sea thrift) from Europe and Elsholtzia haichowensis from China.

As we have seen, copper has been a major factor in nearly all aspects of history, technology, medicine, and culture. It remains crucial in a variety of technologies we are all familiar with today, such as the wire used to access the World Wide Web and chips in Pentium processors. Its importance will most likely continue with the rapid growth of the computer industry, relying on copper chips and copper-based solar power collectors, and with the massive quantities of copper used in the Space Shuttle (approximately 10,000 pounds!). Copper can also be recycled almost indefinitely without losing its form. In myriad shapes and for innumerable uses, it will be with us for a long time.

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