Ideas: A History from Fire to Freud

The earliest iron instruments date from, roughly, 5000 BC, in northern Iraq, Iran and Egypt. But only one of these was smelted, the others being fashioned from meteoric iron. Another early instrument comes from Ur and dates to the early part of the third millennium BC. However, it seems likely that when iron was produced as early as this it had not been recognised as a new metal, or even as a metal at all.⁷² Iron needs higher temperatures than copper (1100°–1150°) in order to be separated from its ore, and it needs a larger furnace, so that the particles of iron can drop away from the smelting zone and accumulate below, collecting into a lump usually called a ‘bloom’.⁷³ Such a procedure seems to have first been developed and practised within the territory of the Hittite confederacy. The Hittites established a state in central Turkey and northern Syria, 1450–1200 BC, where for a while they successfully challenged the Assyrians and Egyptians.⁷⁴ According to Theodore Wertime, the first deliberately smelted iron seems to have been produced when bronze products had reached perfection and where copper, lead and iron ores were in abundance: northern Anatolia along the shores of the Black Sea.⁷⁵ In other words, the success of bronze, the rarity of tin and the abundance of iron induced the Hittites to experiment. The technique appears to have been a closely guarded secret for several hundred years, with the craftsmen keeping the vital details within their families and charging a very high price for their wares. To begin with it was looked upon as a truly precious metal, more valuable than gold according to ancient records; only ornaments were made of it and the secrets of iron were probably not known outside the Hittite sphere of influence before 1400 BC.⁷⁶ (It is likely that the iron dagger found in King Tutankhamun’s tomb had been made under Hittite supervision.) By the middle of the thirteenth century, however, the Hittite confederation had encountered troubled times and, by 1200 BC, the cat was out of the bag, and full knowledge of iron-making spread to other parts of Asia.⁷⁷ The Iron Age truly dates from when the metal ceased to be precious.⁷⁸

Besides its other attractions, iron smelting was less complicated than copper production. Provided there were bellows sufficiently strong to provide a current of air, a single-tier furnace was enough, as compared with the elaborate two-tier, kiln-type furnace which was needed for copper ore to be reduced in crucibles. Furnaces of quite simple design were used during the first thousand years of iron smelting – therefore, once the secret was out, almost anyone could make iron, though naturally smelting tended to be conducted where the ores could easily be mined and where charcoal was readily available. Like tin, iron differs from copper and gold in never being found free in nature, except as the very rare meteorites that fall to earth. Like copper, none of its ores were found in the great river valleys, but in many nearby areas they were to be found in abundance. The most important mining and smelting enterprises of the later years of the second millennium were established in the neighbourhood of the Taurus and Caucasian mountains, and in Armenia.

The crucial process in iron production – carburisation, by which iron is converted into steel – was probably developed in the two centuries after 1200 BC on the coastal areas of the eastern Mediterranean. To carburise iron, it is heated ‘in intimate contact’ with charcoal for a long period, a discovery that must have been accidental (uncarburised iron is not as strong as bronze).⁷⁹ Mount Adir in north Israel is one site of early carburised iron, Taanach and Hazorea in Palestine are others.⁸⁰ In the Odyssey, Homer shows some awareness that the quenching of carburised iron also enhances its hardness.

Given its versatility, hardness, and low cost, one might have thought that the new metal would be rapidly adopted. Bowl-shaped ingots were certainly being traded in the late Bronze Age.⁸¹ Nevertheless, the earliest collection of iron tools that has been found in Egypt dates only from about 700 BC, a millennium and a half after its use by the Hittites.⁸² In Works and Days, Hesiod refers to the men of his own era as a ‘race of iron’.⁸³