Bronze to Iron, the Coming of an Age
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Have you ever wondered what drove modern humans to abandon bronze for iron? In this paper I will present the reasons for and the techniques used to develop iron into a useable metal that is far superior to bronze. Topics will include, when iron was first used, the accidental discovery of steel, and why bronze was replaced by iron. First though, let us look at the origins of iron.
The Iron Age began around 1200 BC, according to Scarre, in southwest Asia (2005:434). It is know however that iron was in use as early as 3000 BC in Mesopotamia, Anatolia, and Egypt. However iron in the Early Bronze Age was rare and very expensive. It is believed that it was as much as 5 to 8 times as expensive as gold. The weapons and tools made from iron were ceremonial in nature, and any other use was strictly ornamental (Waldbaum 1978:15).
During the Middle Bronze Age, 2000 – 1600 BC, references to iron begin to appear in literature with some frequency, but it remained a ceremonial or ornamental metal. It is only in the Late Bronze Age, 1600 – 1200 BC that iron starts to become a working metal in some regions, but even then, bronze remains the main metal for weapons and tools (Waldbaum 1980:75-77). Iron, while it is becoming more prevalent in these societies, it remains an extremely expensive metal, although it is anything but rare, why?
It is impossible to know for sure why iron is so valuable, but many scholars believe that early iron production was not intentional, but a byproduct of smelting other metals (Forbes 1958:9). There is evidence that the Egyptians obtained gold dust which was rich in magnetite sand. While not as dense as gold, magnetite is considerably denser than other common sand minerals, and is often found with gold. Then, when the Egyptians melted the gold, at least some magnetite ended up in the crucible, producing small quantities of iron between the gold and the slag (Forbes 1958:200-201). Theodore Wertime presents one objection to this theory which is that iron is 50% soluble in gold at gold’s melting point, and therefore little iron would be present separate from the gold itself (1980:14).
The final theory I will propose, which is the one that I feel is the most likely, once again is proposed as a smelting accident, but with copper instead of gold. This was the result of experimental archaeology conducted by Theodore Wertime and Cyril Stanley Smith. Based on archaeological evidence, and Near Eastern smelting practices, Wertime and Smith demonstrated that the iron ores sometimes used as flux for copper smelting can be reduced to sponge iron as part of the smelting process (Wertime 1980:13-17). This would explain iron showing up in the Bronze Age in limited amounts. As there was no specific flux used and the quantity of flux varied, the production of iron would seem an entirely random event. This shows the origin of iron, but does little to explain when the Iron Age began.
We have shown that the production of iron preceded the Iron Age by more than 1000 years, when did iron become important to a culture. Waldbaum put forward the beginning was “when iron ceased to be considered precious and was finally accepted as the predominant material for making tools and weapons…” (1978:82). This leads to the question of what did ancient peoples consider “precious”? This also fails to explain why iron replaced bronze. Wrought iron, the first form of iron encountered by Near Eastern smelters, is inferior to all forms of cold worked bronze. It was only when carbon is dissolved into iron in the formation of steel that the ferrous metals have an advantage over bronze (Waldbaum 1980:68).
The development of steel inevitably made iron production essential. 1200 BC is a commonly accepted date not only for the start of the Iron Age, but also for the discovery of carburization of iron, in other words, the development of steel. While the exact location of the discovery of steel is unknown, it would appear that Hattie kingdom blacksmith discovered how to make steel by heating iron in contact with carbon (Muhly 1980:50-52). During the first two hundred years of the Iron Age, iron weapons appear along side those of bronze, with no evidence that iron provided any military advantage over bronze weapons (Waldbaum 1980:84-85). This is not the only model of the start of the Iron Age, so let’s look at another.
Another model asserts that the Hittites discovered carburization around 1400 BC, maintained a monopoly on the new technology for 200 years. Forbes goes on to say that only after the fall of the Hattie nation around the 12th century BC was the technology diffused and did the Iron Age begin. Furthermore, according to this theory, the Hittite collapse scattered the secrets of smelting and carburization throughout the eastern Mediterranean as craftsmen moved out of Asia Minor (1958:217). The