Copper in Ancient Times
Archaeological evidence indicates that copper was used as far back as 10,000 years ago in western Asia. During the prehistoric Chalcolithic Period (Homer, following the Greek practice of around 1000 B.C., called the metal Chalkos. This is why the Copper Age is also known as the Chalcolithic Era), societies discovered how to extract and use copper to produce ornaments and implements. As early as the 3rd-4th Millennium BC, copper was actively extracted from Spain's Huelva region. Around 2,500 BC, the discovery of useful properties of copper-tin alloys led to the Bronze Age.
Copper Was Used by the Ancient Egyptians
It has been documented that Israel's Timna Valley provided copper for the Pharaohs. Papyrus records from ancient Egypt reveal that copper was used to treat infections and sterilize water. The island of Cyprus is known to have supplied much of the copper needed for the empires of ancient Phoenicia, Greece, and Rome. In their hieroglyphics (picture writing), the ancient Egyptians used the Ankh sign to represent copper. The Ankh was also the symbol of Eternal Life, which is appropriate for copper since it has been used continuously by people for 10,000 years.
Copper Has Many Uses, Including Coins
While the Greeks during Aristotle's era were familiar with brass, it was not until Augustus' Imperial Rome that brass became abundantly used. Replaced by iron for weapons and tools, copper and bronze became metals used in architecture, art, and certain specialized uses such as copper pots. The alloy brass, in which copper is mixed with zinc, was discovered sometime before 600 B.C. The state of Lydia, south of Troy in western Turkey, invented the idea of coins as a medium of exchange. Coins were small and portable, had a set value, and were more convenient for trade than the bulky system of barter. Gold, silver, copper, and bronze were used for coins, a use that continues today in our penny.
Greek coins with the head of an owl on the back, known as "Owl Coins", were the most important medium of exchange in the 5th century B.C. Thus, the idea of money was born. The Etruscans reached the glorious days of their civilization about 800 B.C., before the rise of Rome. They were descendents of immigrants from Lydia. In the mountains of the modern Italian province of Tuscany, the ancient Etruscans found copper and tin ores. Iron ore was conveniently near on the Island of Elba. While they created superb iron weapons, they produced magnificent statues in bronze. Joining the Phoenicians in seafaring trade, the Etruscans were rivals of Greek traders around the Mediterranean Sea. Caught between Gaulic invasions from the north and the rising Roman city-state to the south, the last Etruscan city yielded to Rome in 396 B.C.
Recycling Copper in Ancient Rome
Pliny the Elder, the famous Roman historian, wrote in the first century AD about the reuse of scrap copper in Roman foundries. He noted that the metals were recast as armor, weapons or articles for personal use, such as bronze mirrors. The melting and recasting foundries which he alluded to were located at the Italian port city of Brindisi. This city, situated on the Adriatic coast, was the terminus of the great Appian Way, the Roman road constructed to facilitate trade and military access throughout the Italian part of the Roman Empire. Thus, the city was the gateway for Roman penetration to the eastern parts of her empire.
Expansion of the Empire Brought Much-Needed Resources
Rome explored all around the Mediterranean for mineral wealth to support its growing empire. The Romans also acquired immense Phoenecian mineral wealth when they destroyed the Phoenecian colony of Carthage. This wealth included the great metal mines of Spain. A huge copper deposit was found in the soutwest corner of Spain. Copper and iron on the surface of the Earth at that deposit colored a nearby river red. It is thus called Rio Tinto. The mining district was named Rio Tinto as well. The deposit originally consisted of a reddish mountain, with iron, silver and gold as well as copper. Three thousand years of mining have left a crater where the red mountain once stood.
The crater is over 800 feet deep and over three-quarters of a mile wide. In the walls, one can see remnants of Roman tunnels and shafts. Water wheels with bronze axles used to lift water out of the ancient tunnels are still found. Slaves ran the water wheels by walking on treadmills. Mining techniques had changed little. Besides using fires to crack rock, quicklime was stuffed in cracks, then wetted with water. As it became wet, the quicklime expanded, breaking off chunks of rock.
To allow miners to carry ore to the surface, spiral stairways were cut in the rock around the sides of shafts. Where the space was too cramped for stairs, notched poles were used as ladders. Up to 200 hundred pounds were carried by each worker, in leather buckets on their backs. The deep mine workings tended to fill with water despite the water wheels. A drainage tunnel over a mile long and reaching a thousand feet deep was dug to join up with the mines.
Slaves, Workers and Labor Laws
In the early days of the Roman empire, conquests of new lands were being made at a great rate. As a result, many prisoners of war were carried to Spain as slaves. Because slaves were plentiful, conditions were horrible for workers in the mines. Later in the Roman empire, when new slaves were less easy to obtain, slaves became more valuable. Roman labor laws were passed that mandated working conditions for the slaves in the mines. Tunnels and shafts had to be supported adequately with timbers, in order to prevent collapse. Miners were entitled to sleeping and bathing accommodations, food, and specific hours of work. These labor laws were more humane than many miners faced in the early 20th century!
Rio Tinto is still being mined today. Now the miners are working in open pits, rather than the tunnels of the ancient Romans. Millions of tons of black slag remain from Roman smelting operations. The slag contains small amounts of gold and silver, as well as copper, showing that the Romans were interested in these precious metals. Miners today are mining brassy yellow copper "sulfide" minerals such as chalcopyrite. The sulfides were more difficult to smelt than the green and blue copper "oxide" minerals used by the Sumerians. The Romans were fortunate that the oxide ore was closer to the surface, and that there was a great deal of it.
The Romans did find a way to use the sulfide ores, although the process was very slow and probably produced little copper. They collected water that seeped through the mines. Copper dyed the water blue. The sulfur in the minerals turned into a combination of oxygen and sulfur called "sulfate". Sulfate in water makes sulfuric acid. This blue water was called chalcanthus by the Romans. When dried to make a copper sulfate mineral of the same light blue, that mineral is called chalcanthite. The Roman Empire's expansion and wealth depended on mines outside of the boundaries of the original Roman city state. Exploration for new mineral wealth was often the motive for Roman military expansion. Julius Caesar, for example, sought to increase his personal fortune by controlling the tin deposits of Cornwall, when he invaded Great Britain.
To smelt "sulfide" minerals, (that is minerals made of copper, iron, lead and zinc chemically bound to sulfur), it has to be heated and "oxidized" first. The more easily smelted ores were exhausted by the time of the fall of Rome. The Moors lived in southern Spain during the Middle Ages. They used copper for cooking utensils and for ornaments. To continue to mine the still vast sulfide ore deposits of Rio Tinto, they developed a new process. They collected the ore, broke it into pieces, and piled it into heaps. Water was allowed to seep down through the heaps, which was then collected. This technique is called "heap leach." The resulting solution contained copper in the form of copper sulfate. There was far more copper in the water than in the mine water collected by the Romans. Iron was placed into the water containing copper sulfate. A reaction occurred, in which the iron dissolved into the water, and copper precipitated where the iron had been.
Copper Mining at the End of the Roman Empire
During the times of the Roman empire, sufficient copper ore was available to meet the needs of the Mediterranean world's demands, but the ore of Rio Tinto that could be exploited by Roman technology was exhausted by the fall of the Roman Empire. Rio Tinto became a ghost town. Barbarian invasions of the Fifth Century A.D. pushed Europe into the Dark Ages. Europe became a chaotic and dangerous place. Mining and metallurgy, like the rest of European culture, froze in place for centuries.
Did you know...?
Copper was the first metal used by man in any quantity. The earliest workers in copper soon found that it could be easily hammered into sheets and the sheets in turn worked into shapes which became more complex as their skill increased.