The Bronze Age had rested upon two difficult techniques: the miner's work in the dark bowels of the earth, and the smelting together or mixing together of two metals (one of which, tin, was always in short supply) to form an alloy. Since iron ore, in the form of bog ore, was plentiful enough on the surface to dispense for a very long time with any need of mining, and since the metal had multifarious uses without admixture, it is at first sight surprising that the long Iron Age dawned so late. For it does not really begin until about 1200 B.C., when the destruction of the Hittite empire scattered the smiths, though a few pieces of man-made iron were in circulation before 2500 B.C., and iron ornaments and ceremonial weapons soon after 2000 B.C. Two reasons may be suggested for the delay. The early finds of meteoric iron would not prompt any inquiry into the iron ore of the earth, with which they had no obvious connexion. Moreover, an experimental smelting of iron ore to see if it behaved like ores of copper or other known metals would be most discouraging: because pure iron melts at 1,535o C. (compared with 1,083o C. for copper), experiments in smelting it would produce only a mass of slag and cinders concealing unmelted globules of iron. Until the introduction of the blast-furnace in the Middle Ages there was no means of producing molten iron for casting, though from pre-Christian times the furnace temperature was increased either by securing a better natural draught or by using bellows. Repeated hammerings at red heat were required in order to beat most of the slag out of the bloom of crude iron, before it was usable.

But the wrought iron so obtained, though tougher than other available metals, would not take a satisfactorily sharp edge: this was obtainable only with steel, iron containing approximately 0.15-1.5 per cent. of carbon and no residual slag. The problem was only half solved by the invention of cementation, apparently by the 'Chalybes' of Asia Minor, a subject-tribe of the Hittite empire, in about 1400 B.C.; this was a process for steeling wrought-iron bars by repeated hammerings and hearings in direct contact with charcoal, which diffuses carbon into the surface regions of the metal. Some exceptional iron ores yield steel directly if the smelting process is sufficiently elaborated; it was obtained in this way--but much later, about 500 B.C.--in the central European region of Styria and Carinthia, the Roman Noricum. Meanwhile, it had still to be learnt that steel required to be further hardened by quenching the hot metal in cold water, the effect of which upon copper or bronze, which had already been in use for a thousand years or more, was to make it softer. This tempering process seems to have originated about two centuries after cementation. Thus it was not until the last millennium B.C. that ancient iron metallurgy reached its height, and even then it was the metallurgy of the smith with his hammer and his bellows, cast iron being virtually unobtainable with the small furnaces and low temperatures of that period.

Iron began as an ornament, and then slowly became the material for swords and daggers. Iron spear-heads were difficult to make because of the need for a socket, not easily achieved except by casting, and iron battle-axes seem to have been rare, though one has been found in Syria dating from about 1300 B.C.; it had a socket of gold and copper. But the sword was the main gift of the early Iron Age, for bronze was comparatively brittle. The force of the stroke was now limited only by the strength of the human arm; hence the great power of the iron-girt Assyrians when they came down 'like the wolf on the fold'.

New tools of the Iron Age included the hinged tongs without which the smith's work would have been impossible, anvils for making nails, wire-drawing dies, and frame-saws almost identical with the modern hack-saw. The iron file was useful in every kind of metalworking, whereas the earlier bronze file had been little more than a carpenter's rasp. In general, as iron could be made harder, so the older types of tools were improved, until most small hand-tools had something of the quality as well as the traditional shape that they have today.

But we must beware of exaggeration and anticipation. The new metal was used first for weapons; then for the hoe and the axe and pick of the farm and mine; lastly, for the improved tools that we have been describing. Words are deceptive: the iron of early classical Greece, which was not considered suitable, apparently, for ploughshares, was evidently a very inferior metal compared with the properly hardened and tempered material that served the Roman legions about the beginning of the Christian era. Nevertheless, the Greek civilization of the sixth century B.C. was founded upon iron, while the spread of Roman power, which eventually carried that civilization to the farthest limits of the western world, was associated with iron throughout its long history. Iron-mines which the Etruscans started in Tuscany and Elba about 900 B.C. early attracted the covetousness of the Romans, and there were few of the imperial provinces from Spain to alpine Noricum and Dalmatia where iron mining was not among the certain rewards of, and probable incentives to, conquest.

In a survey, however brief, of mining in the classical world, pride of place must be given to the silver-mines of Laurion, which the Athenians worked from 600 B.C. after a much earlier Mycenaean exploitation. Large mines were nearly always worked by prisoners, including prisoners-of-war, whose lives and limbs were deemed entirely expendable. But the imagination is caught by the contrast between the admired democracy of Athens and these slave-worked Attic mines, from which that democracy derived a considerable part of its wealth and consequent leisure. The ore was mostly galena, producing about 60 oz. of silver to the ton. Extraction was in two stages. First, the silver-lead alloy obtained by smelting was repeatedly melted and allowed to crystallize, when almost pure lead first separated. When the silver content had risen to between 1 and 2 per cent., the silver was extracted by cupellation. It was not very efficiently done, however, and the slag-heaps were subsequently reworked with profit more than once, as in many other old mining areas, including the lead-mines which were worked for three centuries on Mendip during the Roman occupation of Britain.

By about the end of the first century A.D., when work at Laurion ceased until modern times, some 2,000 shafts had been sunk, the deepest reaching to about 350 ft. Access was by a series of ladders or notched tree trunks, fixed to the sides of the shafts, the ore being hauled up by rope and pulley in the middle. The roofs of the galleries were supported by leaving pillars of poorer ore unworked. Ventilation was achieved by having parallel galleries, ventilation doors, and sometimes fires to increase the draught. The miners worked by lamplight with pick and basket ( Fig. 42 ). On reaching the surface, the ore was ground to powder and then washed to separate the heavy particles of ore from lighter rock: this process of ore concentration had been practiced by gold-miners in Egypt as early as 3000 B.C. . . .