Excerpts from R.J. Forbes. (1950). Metallurgy in antiquity: A notebook for archaeologists and technologists. E. J. Brill, Leiden, Netherlands.

 

The Early Dynastic period corresponding with the Mohenjo Daro finds shows that Sumerian metallurgy around 3000 B.C. was well developed. Not only are both copper and bronze in use, but the Sumerians know filigrain-, granulation- and incision-technique, they use forging, engraving and inlay-techniques, they solder and practise different forms of casting such as core casting, cire-perdue, open and closed mould casting, etc. It is decidedly superior to contemporary Egyptian technique and the Egyptians do not yet use bronze for many a generation. It is also more advanced than the Indus civilisation metallurgy. (pg. 10-21).

WITTER has proved in a series of brilliant analyses that Central European metallurgy grew up independently and found its own methods in working its specific ores. ...CHILDE proved repeatedly that at least five of the earliest European metal types go back to Sumerian originals and WITTER has not succeeded in proving that no trade routes could have been used from the Near East to Central Europe either by the way of the south, west or south east... The fact of imports of early metal types from the East and such secondary arguments as the existence of an Aryan word for copper derived from the Sumerian URUDU (a substance known very early to the Sumerians as they wrote it with a simple ideogram!) go to prove CHILDE'S contention that Central European metallurgy was founded somewhat before 2000 B.C., by influences penetrating by the way of Anatolia, Troy II and the Danube valley and occasionally by the way of the Russian steppes from Caucasia. (pg. 23).

Not all iron compounds are iron ores, for we know that the criterion is economical production of iron from the compound.  Generally speaking we now consider iron compounds with at least 20-30% of iron to be iron ores., The most important of these ores are:
 

All these ores are oxydes of iron except the types of siderite which are carbonates and therefore contain carbon dioxide and water which should be removed by pre-roasting before the proper reduction can take place. (pg. 381).

We shall have opportunity to prove that the ancients always produced iron in the form of a bloom and that they could not make cast iron.  A bloom is a rough ingot of iron or steel as produced directly from iron ores in a bloomery.  This word bloma (bloom) occurs in English texts before 1000 A.D. (pg. 388).

Wootz is produced from black magnetite ore, bamboo-charcoal, and the leaves of certain carbonaceous plants sealed in a crucible of native clay. Smelting the contents in a charcoal fire with blast air yields a button or regulus of metal, which is alternately melted and cooled again four or five times until round cakes of 5" diameter and 1/2" thick, weighing about 2 lbs, are obtained. These were the Wootz cakes exported in Antiquity to Damascus and later to Toledo and other Arabian metallurgical centres for the manufacture of so-called "damascened steel". This was a high quality steel with a certain pattern dictated by taste. Such damascened blades were forged from wootz cakes by flowing the metal in two or more directions by blows of the hammer. After prolonged annealing the blades were then quenched and drawn to the desired hardness, polished and etched. The last operation brings the "damask" pattern to the surface.  Pattern and colour largely determine the quality of this Oriental steel. (pg. 410).
 
However, as early as the first half of the third millennium B.C. pieces of man-made iron appear in Mesopotamia (Tell Asmar, Tell Chagar Bazar, Mari) and Asia Minor (Alaca Hüyük), and possibly Egypt too.  It is still incertain what ores were worked first. (pg. 417).

But hammering iron cold was found useless.  This experiment must have been repeated many times before it was realised that complete command over this new metal could only be obtained by hammering it red-hot.  By the aid of heat the smith could weld the small pieces of iron together into a larger piece. But the new metal represented no improvement over copper and bronze tools, it was much less easy to work, the forging demanded much expensive fuel and the cutting edge made by hammering blunted quickly. Then he discovered that repeated hammering and heating in a coal-fire followed by plunging in cold water gave the iron a hardness  superior to bronze. The delay of the discovery of quenching was due to the fact that copper when heated softens but is not affected by quenching at all.  Only if heating the iron to white-heat and hammering it patiently followed by quenching the smith would accept the new metal as something of practical use for tools and weapons.  In fact, not before the discovery of steel or case-hardened iron could the metallurgy of iron rise from the status of a tentative experiment.  The difficulties of slagging the ore, working the bloom and forging at white-heat combined with quenching delayed the Iron Age.  It would seem from the archaeological evidence that the earlier stage of iron-working, the production of wrought iron from the bloom obtained from ores, was an achievement of the mountain-region of Armenia
(between Taurus and Caucasus).

From 1900 to 1400 we see the spread of iron ornaments and ceremonial weapons, which remain precious.  It is probable that some of the knowledge of wrought iron working spread too from this same centre in different directions.  The earlier attempts (before 1900), which probably were also made in this centre are still too isolated, but some finds as small smelting sites at different: places, for instance at Ur (of Ur III date, that is about 2300 B.C.!) show that even then the smelting of iron was known and slowly spread.

It would seem from the available data that the "steeling" of iron was discovered in the same centre around 1400 B.C., thus giving the Hittites a monopoly of the manufacture of "true iron" or steel for another 200 years.  Iron objects now appear more frequently as objects of trade in northern Europe of the thirteenth century B.C. (Seeland and Bornholm!).  An early Italian smelting site at Nevigata near Manfredonia, Apulia, must be dated before 1200!  But whatever progress iron trade made, the new metal was still subordinate to copper and bronze. It is even doubtful whether steel was more frequent in Asia Minor itself than say in Palestine and Syria, where iron begins to penetrate between 1400 and 1200. (pg. 417-418).

In the fifteenth and fourteenth century B.C. the stream of European imigrants begins to move southwards and it is not coincidence that the earliest references to iron-working in Asianic-Egyptian texts correspond so nearly with the invasion from Europe!  That the use of iron was forced upon Asia by conquering races is implied by the widespread taboo of this metal. This is quite natural for peoples at a disadvantage of securing raw materials or working them, for from the Upper Nile to the Caucasus there are no deposits comparable in quantity and quality to the spathic iron of Europe, the best ore adapted to the groping technique of iron-working. Again Hallstatt forms have a long history behind them, as the metallurgical progress of Central Europe was quickened between 2000 and 1500 by the trade with the East.  The claim of the "Caucasian" region is nothing but an epic tradition without tangible proof. The earliest hoard of iron work mentioning is that of Sargon II, even among the Hittites iron was only common after 1200, their ores being only low grade haematite and some magnetite. (pg. 419).
More notes from this text are in our information file on furnace types.  We also suggest you see our information files on early furnace technology for some schemas and precursors of the blast furnace.