The beginning of metallurgy

By Cultura Animi Foundation with the Cooperation of EURO INNOVANET SRL

Stone tool manufacturing was one of the earliest technologies employed by humans. It was developed nearly two million years ago by remolding of natural raw materials, for example through chopping or sharpening stone or bone. Later were developed composite technologies that required the combination of raw materials and special processes to create something new and different-for example, clay, fire and water were combined to produce ceramics.But the possibilities for producing durable artifacts, which could be reused or refashioned after they became worn-out or broken, were very limited. And only when human societies learned to develop technologies that would let them turn ore into metal, they were able to create artifacts that could be used to the point of wearing out and then to be ''recycled'' into something new. With the appearance of metallurgy, the products manufactured by human technology could be used repeatedly, and this way both the products and the knowledge involved in their production became more precious and valuable to their makers.

The periods of human development usually have been named after the main material that was used for tool production. The Stone Age (divided as Paleolithic, or Old Stone Age, and Neolithic, or New Stone Age) lasted for several millions years and is the longest one in human history. During that period the tools were made only from stone, antler and bone.

The emergence of metallurgy is a hallmark for another stage of mankind’s development. The economy had drastically changed and became dependant on the metals. So the following prehistoric periods are known as Copper Age or Stone-copper Age (Eneolithic or Chalcolithic), Bronze Age and Iron Age. In some languages the word ''iron'' is used also for ''strong'', while ''golden'' is used for ''precious''. The so called ''precious metals'' like gold, silver, platinum etc. had made possible the development of the world economy as we know it now.

Metallurgy had developed independently across the world in different cultural contexts in the Balkans, the Near East, Mesopotamia, Southeast Asia, North America and Central America. That is why the precise timing of the advent of early metallurgy and its spreading throughout the world has been an object of many discussions.

The prevalent theoretical concept in the beginning of 20-th century assumed that most cultural innovations occurred firstly in the Near East and then spread out by the process of cultural diffusion and migration throughout Eurasia.  Later though the archeologists found evidence for production of copper during the Neolithic Age and the Copper Age in the area of the Balkans in South-East Europe, as well as in the Near East and Mesopotamia.

Copper

In his article entitled "The Autonomy of the South-East European Copper Age" Colin Renfrew, using both absolute and relative dating methods, convincingly demonstrated  that development of copper smelting technology occurred earlier in the Balkans than in the Near East and Mesopotamia. In addition, Renfrew argued that metallurgy was not "a single invention, but a number of distinct and separate discoveries." While the precise chronological relationship between early metalworking technology in South-East Europe and South-West Asia remains unclear, by the fifth millennium B.C. copper production in South-East Europe was more advanced than its Asian counterpart, and was influencing considerably the trade networks and socio-economic organization.

In those lands there were deposits of native copper which probably was used for tools production up to the Roman period, but then those deposits were almost totally exhausted.

Copper wedge, Slatino, Kyustendil museum

By the middle of the fifth millennium B.C., much larger copper tools have being produced, initially in the form of flat copper axes or wedges and later in the form of "hammer-axes" with a hole for hafting. By the end of the fifth millennium B.C., toolmakers have been producing already ax-adzes and large chisels.

 

Unlike the raw material sources for producing stone tools and ceramics, which are found everywhere in South-East Europe, sources of copper ore occur only in very specific microenvironments. The copper ore sources in South-East Europe are concentrated in veins that run through limestone massifs in the Balkans, mostly in Bulgaria and Serbia, where mines dating back to the Copper Age have been discovered. There are copper deposits also in Transylvania, but so far there is no evidence that these sources were exploited in prehistoric times. Metallurgy based only on copper, did not have any prospects for further development, because it was replaced by Bronze and Iron metallurgy, which proved to be more efficient for making tools and weapons.

Gold

About the same time when copper started to be extensively exploited in the region, artifacts of gold also began to circulate and to be deposited in the ground, primarily in mortuary contexts. Compared to the complex technological processes necessary to process copper, much less effort was required to work on gold. Since the raw material itself is very soft, it easily can be hammered and molded without being heated. Gold could be found in Bulgarian rivers, and probably in the prehistory gold have been extracted also in mines.

The vast majority of gold in South-East Europe comes from the Black Sea coast of Bulgaria. Most of the gold artifacts are small adornments or clothing decoration found in burials. Over three thousand gold objects were recovered from the fifth millennium B.C. cemetery near the city of Varna. Gold artifacts in the Varna cemetery include cinched beads, thin sheets, spirals, diadems, earrings, bracelets, and a phallus sheath. Other gold artifacts have been found in fifth millennium B.C. context in the Great Hungarian Plain, as well as in other sites of northern and eastern Bulgaria.

A rare example of vast amount of golden artifacts is provided by the Hotnitsa golden treasure. They were discovered in different spots of the site, which is a proof that the so called ''treasure'' is not an isolated phenomenon, but the golden objects were worn by living owners and were scattered under different circumstances in different places.

Bronze

In the middle of the fourth millennium B.C., metalworkers in the northern Balkans began to experiment with different alloys. They mixed copper with other metals, such as arsenic, which in some cases occurred as a natural impurity in copper ores. By the second millennium B.C., probably by diffusion from Anatolia, the metalworkers learned that one of the best alloys for copper was the tin. The combination of these two metals created a new material that was much harder and much more durable than copper and still could be recycled and reused in a similar way. It had one more advantage-out of it could be made sharp and durable blades. That material was the bronze.

Bronze is an alloy. It is a mixture of two or more metals melted together which produces a new metal with new and different properties. The bronze was the first metal that could be successfully cast without complicated secondary operations like forging. Such casts were made of stones and clay and were discovered all across Eurasia. About 3000 B.C. fearful weapons made of this new alloy, the bronze, became the basis for development of new economy and lifestyle - the Bronze Age started.

The Bronze Age was the time period of the beginning of real warfare. The bronze provided opportunities to develop different type of arms-for cutting (swords and knives), stabbing (daggers, rapiers, arrows, spears) and sabering (battle axes and sabers). The development of the offensive arms evoked rapid development of defensive armory (helmets and armors). Almost the entire quantity of extracted metal was included in the warfare (it is a rarity to find agricultural tools of bronze in the Bronze Age context. It should be mentioned that the Bronze Age had introduced the horse as a part of the warfare. So the movements in the northern Blacks Sea cost provoked series of turbulence in the Balkans and Central Europe.

The production of metal was a priority of small group of specialists and was considered as sacral. Even from the copper age onwards the metallurgy was the reason for the social stratification and formation of elite. The difficult process of metal extraction and production, and the constant increase of the needs of bronze was the reason for permanent hunger for metal. This is well seen in the numerous bronze storing hoards all across Europe. This turmoil in Eurasian world demolished cultural and commercial centers; trade routes were cut off and destroyed. Finally this caused a collapse of the Bronze Age and the appearance of iron.

 

Iron

Now it was the iron that changed life-both in economy and agriculture, and it was the iron again that had pushed the things toward industry due to the need of plentiful tools and weapons. The main reason why iron did not show up in the Western world earlier than about 1500 BC was that it could not be melted or cast because of its very high melting point of 1539° C. Such a temperature was unachievable until the start of the industrial revolution. True, iron was used even before that, because it has one useful property- at the temperature of fire fostered by bellows iron could be turned into spongy mass mixed with slag, called bloom. With repeated hammering the blacksmith could drive out the slag and get a bar of almost pure iron. However this iron had several negative properties: it was softer than bronze, did not hold a good edge and easily got rusted.

The iron can be extracted from the minerals hematite and magnetite. There were two ways to improve the iron: steeling - when working with bloom the charcoal and carbon monoxide, produced by the fire, will diffuse into the surface, the content of the carbon increases to 0.3% (here the iron becomes  better than bronze), and if the carbon content increases to 1.2% the iron acquires excellent qualities; tempering: this involved two stages – first, sudden cooling of the hot metal by plunging it into water which makes it harder but somewhat more brittle, after that re-heating to about 700°C and then cooling again to remove some of the brittleness and adding of hardness. Because heating the iron to its melting point was not possible in ancient times the blacksmiths had stay tied to the anvils at least for a thousand years more, which stumbled the mass production of iron goods. Such was the situation in Europe, although the Chinese used cast iron for 2000 years before it was used in the Western World. They could melt it in better furnaces due to more advanced technologies which they kept in deep secret. They reached higher furnace temperatures since they knew the usage of horizontal bellows and double acting box bellows, and they burned large amounts of fuel with higher carbon contents in relation to the amount of iron ore being smelted, which caused carbon monoxide to enter the iron and lower the melting point to about 1150° C. These processes allowed the Chinese to cast iron.

The earliest dated usage of iron appears around 4000 B.C. Probably this was processing of meteoritic iron. This special type of iron contains a high percentage of nickel which helps the iron to resist oxidation. Meteoritic iron is different from the earthly iron found on earth. All of the early iron products were probably made out of meteoritic iron. But soon its supplies were exhausted and the described above technologies had to be applied.

The iron production gave a considerable impact on the economy. And out of iron were made not only weapons, but also tools for everyday use.