Nipissing University

History 2055 -- Ancient Civilizations

Early Developments in Metallurgy -- Incomplete

Steve Muhlberger
Much of the interest of ancient history is tracing origins, whether in politics, religion, or technology.   This lecture and the next treat the development of tools crucial to civilization. The subject of this lecture is the development of metal tools.  A great many things we take for granted cannot be done efficiently, or at all, without appropriate metal tools.   Advances in technology have very often depended on advances in metallurgy.

The use of copper, bronze, and iron are, as far as we can tell with present knowledge, one of the great contributions of the ancient Middle East to human technology.

Stone Age, Bronze Age, Iron Age. Everyone has heard these terms used to describe the past. Their origin is in archaeology. Long ago, archaeologists focused on the types of tools available to ancient cultures as a key to classifying them.  The ages of Stone, Bronze and Iron provide us with a very rough relative classification of cultures across the Old World. But remember that this classification only measures one thing. It does not measure time in any absolute sense. The Bronze Age is not the same period of time in every region of the world. The Bronze Age was much later in Scotland, say, than in Iraq or Iran, because the techniques of bronzeworking were invented in Asia and spread to Europe and across Europe rather slowly. Large parts of New Guinea were still in the Stone Age this century while the rest of the globe was well into the Iron Age, Steel Age or Plastic Age.

Nor does this classification measure civilization in any simple way. When we are talking about technology, we are talking about power and potential, not results.

The very first metal to be used in tools was copper. Most metals do not occur in a pure state on earth, but are combined with a variety of non-metals in compounds called ore. Copper, too, occurs most often as an ore, but also, on occasion, as in a pure metallic form called "native copper." Gold, too, is found in a native form, but it cannot be made into tools. Copper can. Simply by hammering native copper, it can be shaped and hardened into a useful tool.

From an early date people were doing this in the Middle East and no doubt other parts of the world. By the 5th millenium B.C., well before writing was invented, Middle Easterners were not just hammering copper, but melting it, pouring it into molds, and casting the metal into the shapes they wanted.

Melting copper requires a very high temperature: 1083 degrees C. One wonders how they figured out that melting copper was even possible: after all, one does not accidentally stoke a fire up to 1000 degrees, not in ancient conditions.

Early metal workers probably took the first steps towards melting when they learned to anneal metal. Annealing means heating a brittle piece of metal to make it malleable after it has become hard from too much hammering. Smiths frustrated by the breaking of over-hammered native copper figured out that heating the stuff made it workable again. Someone pushed this insight as far as it would go, and discovered that high temperatures actually melted the stuff.

It is very likely that the furnace used to do this was a on a hillside, designed so that the natural winds would stoke the fire by itself.

Further experimentation led to the smelting of copper from its ores. This stage in metal technology was probably easier to surmount than the earlier one. Copper can be smelted out of ore at a much lower temperature than native copper can be melted. Melting takes place at 1083 C, while smelting only requires 700 to 800 degrees.

Smelting was probably a direct by-product of melting native copper out of a matrix of ore. In the right conditions the smith got both melted native copper and new metal smelted out of the rock. Smiths very quickly understood that they were getting more metallic copper from the furnace than they had put in, and began smelting on a routine basis.

Copper, once smelting was mastered, became the first widespread tool metal, and its use quite quickly spread across the Old World. Properly worked and used, it is very practical. Only copper and stone tools were used to make the Great Pyramid.

But alloys of copper are even more practical. The next step in tool technology was the invention of bronze. Bronze is an ambiguous term. It can mean at least two different alloys, copper with tin, or copper with arsenic.  Either of these compounds is a metal harder than pure copper, easier to cast, and less easily corroded. It became the dominant tool metal of the third and second millenia B.C., which, as far as the most civilized areas are concerned, constitute the Bronze Age.

Copper and arsenic are sometimes found in the same ores, and the simple smelting of that ore in accordance with existing technology would sometimes give you bronze. Arsenical bronze has been found at one site in south Iran dated between 4500 and 4000 B.C. But further development was slow, and bronze was not common until close to 3000 B.C.

Before that date, smiths were mixing arsenic ore and copper ore and producing arsenical bronze on purpose. Arsenical bronze is a very good metal in some ways. The arsenic tends to concentrate at the surface of the metal piece, where it can be polished to a mirror brightness. That beautiful arsenic, however, is also poisonous -- which is perhaps why many smith-gods in many mythologies are lame.   Years of handling arsenical bronze would slowly poison the smith, producing muscular atrophy and loss of reflexes.

Fortunately, another form of bronze appeared around 3000 B.C. This was tin-bronze. It was at first the rarer form, because tin is not found in very many places in South Asia, North Africa, or Europe. It does occur in eastern Iran, and in the Zagros mountains between western Iran and Iraq. Despite the relative rarity of the essential ingredient, tin-bronze quickly became the preferred form of the metal. All kinds of intricate work was being done in bronze all over the Middle East by 2500, not just in Mesopotamia but in Syria, Crete, and the Aegean Islands, as well as the Indus Valley. From this old civilized area it spread to the rest of the Old World. 

Bronze age metal implements survive the centuries much better than later iron ones, and so we can see how beautiful some of it is. The fact that you can cast bronze quite easily once you have learned how to make it accounts for the artistry.

One of the fields where their talents were especially appreciated was in the development of weaponry and armor. Perhaps there was copper armor at some point, and surely there were copper weapons. Bronze was much more suitable for both purposes.

Bronze was used for all kinds of implements, not just weapons, and it was correspondingly important in economic and political calculations. Rather than seeking to control the trade in radioactives, computers, and cocaine, rulers in the years before 2000 B.C. were very interested in the supply of tin. Tin opened trade routes and often closed them. Some of the earliest large-scale contacts, at least in historic times, between the Middle East and Mediterranean on one hand and the Atlantic world on the other came about because Cornwall is, or at least was, a very important source for tin. By 1000 B.C., that trade was flourishing. It has been suggested, on the basis of probability alone, that a seaborne connection between the Aegean Sea and Cornish tin mines already existed in 1400 B.C.

Bronze never ceased to be valuable and useful in ancient times. It eventually, though, was pushed aside as the premier tool and weapon metal by iron. Iron is a natural for tool-making. For one thing, iron ore is extremely common . But iron only slowly was put to use, because  iron must be worked at very high temperatures.

You will recall that copper can be smelted at 800 degrees or less, and melted at 1083 C. Bronze, being mostly copper, requires temperatures that are no higher. Iron is smelted at 1200 degrees, and melted at 1528 C. It may seem that the difference between 1083 C and 1528 C is not so great. For those of us who do not work with such heats, it seems that if ancient smiths could reach 1100 degrees they might well reach 1500. But in actual fact they never got beyond 1400. This means that in antiquity iron could not be melted and cast.

Iron was worked by hammering. This was no easy matter. Iron ore, when smelted at 1200 degrees, produces spongy iron mixed with impurities. Since these could not be removed by melting, forging had to be used:  smelted iron was repeatedly hammered while hot to make the spongy iron more solid and to remove the impurities by pure brute force. If this sounds like hard work, it is.

Furthermore, it takes brains and technique as well as muscle to end up with a metal worth having. The iron must be mixed with the right amount of carbon, or it will not be hard: carbon-free iron produced by forging is called wrought (worked) iron, and it has its uses, especially for decoration, but wrought iron could never replace bronze for tools. Wrought iron can be reheated in contact with carbon-bearing materials like coal, coke, or in ancient times, charcoal and then quenched suddenly in water or oil; it then becomes steel. At least, the outer layer becomes case hardened. Under the case of steel you still have wrought iron.

Needless to say, the whole process is not immediately obvious, even to an experienced bronze-worker. Bronze work is really much simpler. All of these complications are enough to explain why the Bronze Age lasted a long time. The available technology was good enough that the problems of iron working were easily ignored.

Indeed, iron was a very rare metal before the second millenium B.C., as aluminum was before this century, and most of it was from meteorites.

Around 1900 B.C., about the time that tin-bronze was beginning to be the dominant working metal, iron became just a little more common than it had been before. Documents from Anatolia show us that iron was known and iron was produced on purpose. The activities of the metal workers of this area are documented in the cunieform records left by an Assyrian merchant colony in Cappadocia.
Iron was called amutu and was produced in very small amounts, under royal control. The king of the area gave gifts of amutu to those he wished to impress. When it was sold, it brought eight times its weight in gold.

In the years before 1500 B.C., ironworking spread to a few other sites in Syria, Mesopotamia, and Iran. It was still a very rare and expensive item. It is very likely that it was being made as a by-product of copper smelting, when hematite (iron oxide) was used as a flux to reduce the melting point of the ore  Sometimes this process produced metallic iron.

After 1500, iron gradually became more available. Yet one still needed lots of wealth to obtain it. It only slowly was put to practical use. Most iron displayed. One eccentric Assyrian ruler of 1400 B.C. accumulated enough for a suit of armour for a horse, including a breastplate and limb coverings. This must have been an unusual extravagance.

The only place where the process of iron-smeltin was understood at all well was in Hittite-ruled parts of Anatolia. This part of Anatolia had a long history of metal working, and iron ores were available. By about 1300, Hatti, as the kingdom was known, was famous as the source of good metal. We have some correspondence between a Hittite king and an Assyrian one which shows that iron was still a prestige item not generally available, even to kings

It is hard to tell from from our sources how much more common than it had been 600 years earlier, when Anatolia had already a similar monopoly of the metal. But if the king of Assyria had to depend on foreigners for his supply, we can be sure that the technology was something of a secret.

Eventually the monopoly was broken, and the knowledge of how to work iron began to march across Asia and Europe. The date of this development differs in different works. The traditional date for the beginning of the Middle Eastern Iron Age is 1200 B.C.; H.W.F. Saggs believes the effective Iron Age did not begin until 1000 or 900 B.C. This disagreement reflects the very gradual adoption of iron into daily life. Bronze in some ways was superior to iron, and certainly was easier to work. So iron was taken up by stages. First it was put into weapons, initially royal and ceremonial weapons, then weapons for rich warriors, then, very slowly, weapons for general use. By the 11th century, between 1100 and 1000 B.C., agricultural implements of iron were common enough to show up in archaeology, but they were still outnumbered by bronze tools. In the eleventh century, even weaponry was still mainly bronze.

It was only about 900 B.C. that iron usage became routine enough in the core areas of Mesopotamia and Syria to figure in an important kind of record: the record of loot. Kings liked to commemorate their big victories on stone monuments, and these records survive well. Bronze and tin figured as loot and tribute in early records. Iron did not join these metals until about 890.   Similarly the Bible indicates that 900 was when iron became a routine fact of life.
 

 


BIBLIOGRAPHY

William McNeill, The Pursuit of Power(NU)

H.W.F. Saggs, Civilization Before Greece and Rome

Encyclopedia Britannica, "Hand Tools," vol. 8.


This site has been visited times since September 1, 1998.


Copyright (C) 1998, Steven Muhlberger.