Metalworking

Abundant copper and bronze tools and ornaments are known from all the Harappan towns and cities, and they occur even in small rural settlements. Evidence, such as copper prills and fragments of clay kiln lining and crucibles, and occasionally kilns, indicates the presence of metal workshops in many settlements.

Copper and Bronze. Analyses of Harappan artifacts suggest that almost all the copper used was either native copper or copper oxide ore, rather than copper sulphide ore, which is harder to work (though the latter is known in the early levels at Mohenjo-daro). Trace element analysis suggests that the Harappans obtained ore from several sources, notably the Aravalli Hills and Oman (Magan).

As yet, no definite evidence of copper smelting has been found in Harappan settlements; so copper was probably imported as smelted metal. This was certainly the case for copper from Magan, where copper was smelted, refined, and made into bun-shaped ingots at sites adjacent to the mines. Such ingots have been found at Lothal, Mohenjo-daro, and Chanhu-daro; however, this form of ingot need not be diagnostic since it is the shape produced naturally when smelted metal settles in the base of a bowl furnace, and it was therefore widespread in antiquity. Small square - and round-sectioned copper rods of refined copper may also have been ingots, in a form that could readily be made into artifacts by cold hammering; such rods are common at Mohenjo-daro.

It is assumed that Aravallis copper was also smelted near its source by the people of the Jodhpura-Ganeshwar culture. The traces of copper working kilns so far detected at Mohenjo-daro, Harappa, Kuntasi, and Lothal suggest that these were used for refining matte (roughly smelted copper still containing impurities) and for melting the metal for casting and alloying. Two types were used at Lothal: a circular kiln with a long flue for using bellows to circulate air and raise the temperature, and a rectangular type with a surround of baked bricks. A bowl-shaped crucible was also found there and a boat-shaped crucible at Dholavira.

However, polluting industrial activities such as smelting are likely to have been located on the outskirts of settlements or beyond, so they may still lie there undiscovered. It is possible that copper smelting occurred at Mohenjo-daro in an industrial area uncovered well to the east of the Lower Town, where chank shells were cleaned and where slag and fragments of furnace walls have been found. The possibility of smelting at Mohenjo-daro may be supported by the discovery in the DK area of a brick-lined pit in which copper oxide ore was stored.

Copper was used to make many everyday objects; since broken metal objects could be recycled, the examples discovered must represent only a fraction of those that were used. These included knives, daggers, razors, arrowheads, spearheads, axes, adzes, chisels, punches, barbed fishhooks, tubular drills, and various types of saws, including the true saw with teeth set alternately to left and right. Harappan copper/bronze saws could apparently cut shell as efficiently as the steel saws used today. There were also rings of copper wire, in a plain circle or a spiral, and copper beads and spacer beads. Most of these were of a very simple form that could be created by cold hammering and annealing or by casting in a one - or two-piece mold. Molds of sandstone and steatite have been found, for example, at Chanhu-daro. One cast copper axe from Mohenjo-daro was finished by dipping it into molten copper to give it a smooth outer shell. The straw-tempered crucibles used for heating metal were apparently heated from above, rather than from below, reducing the potential strains on them. Straw-tempered clay was also used to coat the walls of kilns for firing pottery and heating metal.

A dagger from Harappa (left) and a spearhead from Mohenjo-daro made of copper/bronze. Both are simple flat objects with no strengthening features such as a midrib, so they could not have been effectively used as weapons. They were, however, easy to manufacture and easy to repair.

(J. M. Kenoyer, Courtesy Department of Archaeology and Museums, Government of Pakistan)

A shell ladle, probably used to pour libations in rituals. It was therefore a valuable object, thought worthy of repair. A lead rivet was inserted to mend a hole in its base. (The crack is more recent, due to the lead expanding and corroding.) (J. M. Kenoyer, Courtesy Department of Archaeology and Museums, Government of Pakistan)

Some objects such as metal vessels were made in several pieces that were joined by cold hammering. Stone anvils and hammerstones are known, for example, in the coppersmithing workshops at Kuntasi and Lothal. Other techniques used for joining included riveting and running on.

Many people have commented unfavorably on the technological simplicity of Harappan metal tools, pointing out, for example, that the Indus metalworkers were still making simple flat axes when their neighbors were making technically more advanced shaft-hole axes. It seems that the few shaft-hole artifacts found in Indus sites were all imports. Nevertheless, the use of simple technology was clearly a matter of choice since Harappan metalworkers also produced a range of sophisticated and complex products. These were made in specialist workshops in the cities, whereas the production of everyday objects was more widespread, with local metalworkers investing their time in mass-producing simple but practically efficient tools rather than turning out smaller numbers of more sophisticated products.

Bronze figurines show that the Harappans were masters of complex casting using the cire perdue (lost wax) technique. The most famous example is the Dancing-girl from Mohenjo-daro. Fine copper or bronze bowls and dishes were raised by beating a piece of copper over a bronze anvil, such as the snarling iron (a bronze bar with a convex surface at each end) identified at Chanhu-daro. This was found in a metalworking workshop along with several of the bowls that would have been raised on it and a number of other metal objects. In addition, there was a set of scale pans for weighing the metal. The opposite method, sinking, was also employed by the Harappans to make vessels. Copper wire was made, probably by drawing the metal through grooves cut in a stone block. A necklace made of tightly coiled wire was found at Harappa.

Although the majority of Harappan artifacts were of unalloyed copper, Harappan metalworkers made various alloys of copper, with tin, lead, arsenic, and even silver. Since tin was rare and had to be imported, it was used sparingly. Arsenic may have been deliberately alloyed with copper; however, arsenical copper ore was found in both Oman and the Aravalli Hills, so it is more probable that a natural alloy containing a low percentage of arsenic was deliberately selected because the Harappans appreciated its qualities. Arsenical copper was harder and stronger than pure copper though not as hard as tin bronze; the latter was also easier to cast. The alloys used were carefully matched to the purpose for which the artifacts were designed. Unalloyed copper was used for objects that did not have to stand up to hard use, but those, like knives, axes and chisels, that were for use against hard surfaces were made from copper alloyed with up to 13 percent tin: conventional bronze. The proportion of objects made with tin bronze increased during the Harappan period, presumably indicating an increase in the availability of tin. An alloy with much higher levels of tin, sometimes combined with lead, was used to make surfaces that would take a high polish for mirrors and attractive vessels.

Gold and Silver. Electrum was used by the Harappans: either natural electrum from South India or electrum produced by alloying gold and silver. These metals were also used separately. One possible silver workshop at Mohenjo-daro yielded a small crucible, a silver-lead ingot, and slag. Lead and silver may have been smelted there and at Harappa, though the evidence is slim. Objects of silver and gold have come mainly from Harappa and Mohenjo-daro; only a few are known from other sites, such as gold beads at Lothal and Banawali, and gold and silver objects in a jewelry hoard at Allahdino.

Gold was used mainly to make jewelry such as pendants, ear ornaments, cones, brooches, and beads. Bangles were made from hammered gold sheet, curved round into a hollow tube. A hoard found in the HR area at Mohenjo-daro included a necklace with gold spacer beads made by soldering a pair of disc beads edge to edge. Another necklace from Mohenjo-daro had spacers of strips of beaten gold, perforated to take six strings of beads. A Late Harappan hoard, accidentally discovered in 2000 CE at Mandi in Uttar Pradesh, contained a number of gold necklaces of paper-thin disc beads, spacer beads, and semicircular terminal beads, as well as tubular gold and silver bangles or anklets. Gold was hammered into sheets from which fillets, worn to secure the hair, were cut; these were burnished, erasing the hammer marks, and perforated at the ends. Gold sheet was also used to cover some terra-cotta beads found at Banawali, and several gold beads with a copper core and a button of gold sheet were found at Harappa. Gold beads and pendants were often combined with stone beads in necklaces and bracelets or anklets. Some more elaborate ornaments were also made by combining these materials. For example, two identical brooches found at Harappa had a gold base to which gold bands were soldered to form cells in a double-spiral pattern, which were filled with beads of blue-glazed steatite with gold ends, set in mastic.

Silver was also used to make jewelry. Silver wire and foil were made into bracelets, and silver wire was coiled into rings. A necklace of silver discs and spacer beads was among the jewelry in a hoard concealed in a jar at Allahdino, along with two or three necklaces of silver beads, several gold fillets, and other necklaces of stone and copper beads. Two seals made of silver were found at Mohenjo-daro, each bearing the common unicorn motif. However, silver was used mainly for vessels such as the elegant jars with lids found at Mohenjo-daro.

Many of the techniques used in working copper and bronze were also applied to gold and silver. In addition, Harappan jewelers used filigree and granulation in the production of their finest objects.

Other Metals. A number of lead ingots have been found but only a few objects of lead are known, for example, plumb bobs. A shell ladle from Harappa had been mended using a lead rivet. Lead was sometimes alloyed with copper, producing a more ductile though softer metal that was easier to cast.

It has been claimed that iron was produced in third-millennium South Asia, objects of iron being reported from Lothal and Chanhu-daro, as well as from Ahar in Rajasthan and Mundigak and a few other sites in the borderlands. It is possible that these objects were made from meteoric iron or were hammered from iron in slag produced either as a by-product of smelting iron-rich copper sulphide ore or when iron oxide was used as a flux in copper smelting. As in the contemporary Near East, iron would at this time have been a curiosity rather than a metal in regular use.