METTALLURGY: In Indus valley Civilization

Metallurgy in India has a long and varied history. Bronze and copper were known during the period of the Indus Valley Civilization. The recovery of metal articles (including a bronze dancing girl) and the discovery of crucible with slag attached are clear indicators of the knowledge of casting (pouring molten-hot metal into moulds of the desired shape and size) and forging (hammering hot metal into required shapes). Further, this points to the fact that these early peoples could produce and handle temperatures as high as 1084° C (melting point of copper), as also 1065° C (gold), 960° C (silver), 327° C (lead), and 232° C (tin). Working with iron with its melting point at 1533° C was inarguably a later achievement.
Mohenjodaro, Harappa and Lothal are the three major sites of this civilization. At Lothal in the state of Gujarat, two types of kilns have been excavated, One, a circular kiln that measures 1 metre in diameter, that was most probably used for smelting copper ingots; the second, a rectangular kiln measuring 75 by 60 cms. with a depth of 30 cms. This is believed to have been used for casting tools.
The many metal discoveries at Lothal include figure, amulets, pins in the shape of a bird-head, miniature figures, and tools such as a curved or circular saw, a needle with an eye at the piercing end, and a bronze drill with twisted grooves. This last is by far the most important find of ancient tools because this single item led to an unparalleled precision at the time, and is widely regarded as the precursor to modern machine tools.
The above-mentioned tools are exceptional in the entire Indus Valley civilization, and neither do they bear resemblance to Harappan tools. Indeed, Lothal was already a prosperous town prior to the arrival of the Harappans sometime around 2450 BC and till 1600 BC.
One thousand and fifty BC is usually accepted as the year the Iron Age began in most of India. Iron is mentioned by the Atharvaveda, referred to specifically as ayas. Previous to this, the Vedas used the term ayas as a generic one for metals : the Brahmanas and the Upanishads referred to Lohitayas (i.e. red metal or copper) and Krishnayas (i.e. black metal). One thousand BC is the accepted date for the appearance of extracted iron.
Iron and its technology gave momentum to the process of urbanization, and the lives of the peoples changed in reflection.

A Clockwork Furnace! Metallurgical skill best exemplifies the Indian propensity for evolving simple techniques and processes that could be adapted to a complex scale. Ironsmiths perfected their art and indigeneous methods were to prove faster and more efficient than contemporary European ones in the years to come. The rough construction of the small furnaces belied the precision of their interiors. The ironsmiths could construct, demolish and reconstruct to get the correct angle of blast. The entire exercise required no more than simple tools and a few hours. These furnaces were efficient by existing standards for smelting iron and for making steel. production of one unit of crude iron entailed two units of charcoal. Iron was directly carbonized to steel by placing it with charcoal, green leaves and wood in closed crucibles. European methods of the time required days while the above-mentioned processes took a matter of hours.

Iron was closely associated with :
o Painted Grey Ware Culture -- the iron objects of this association date back to 1025 +/- 110 BC. Excavations have revealed arrowheads (including leaf-shaped ones), daggers, hoes, adzes, spearheads with tongs, fish hooks, and plain tongs. A vital site - Atranjhikera - has yielded implements at practically every level of excavation! Other sites are Hastinapur, Alamgirpur, Kausambi and Ujjain.
o Black-and-Red-Ware-Culture -- objects discovered at Eran in the state of Madhya Pradesh date back to 1250 BC and 700 BC, according to C14 dating. Another site, Nagda, has 59 objects, all belonging to the period 750-500 BC. These include a double-edged dagger, the round socket of a broken axe, arrowheads with a biconical cross-section, a celt with a wide cutting edge, spoon, nails, clamps, and knife blades. o Megalithic Culture -- While the rest of the country proceeded from the Neolithic to the Copper and then to the Iron Age, South india moved directly from the Neolithic to the Iron Age. At Hallur, the Iron Age is believed to have begun in 1105 BC, while the rest of the South coincided with the North i.e. approximately between 1050 and 950 BC. Spread throughout this region, implements and tools are marked by their similarity. Flat iron axes, sickles, spades, daggers, swords, knives, chisels, tripods, horse-bits, frying pans, ladles and even bangles - all point to a usage for both domestic and warfare purposes. Taxila stands apart due to the clear Graeco-Roman influence, for example, ladles with vertical handles, folding chairs, candelbras, plate armour for men and horses, cheekbars. Of special interest are the arrowheads that are distinctly Mediterranean in style, and made their appearance in both distant regions in AD 1!

The Special Four
1) The Iron Pillar in the Qutb Minar complex at New Delhi is an AD 310 structure, and has survived corrosion-free! It stands at 23 feet & 8 inches, upper diameter - 12.5 inches, lower diameter - 16.5 inches, and weighs 6 tonnes. Analysis of the pillar - iron: 99.720%, carbon: 0.080%, silicon: 0.046%, sulphur: 0.006%, phosphorus: 0.114%, manganese: negligible. The low levels of sulphur and manganese, and the relatively high level of phosphorus, are credited with its rust-free existence.

Iron Pillar in the Qutb Minar complex at New Delhi

2) Iron Pillar at Dhar (near Indore) is believed to have been built during Chandragupta Vikramaditya's reign, between AD 375 - 413. Originally 50 feet in height, it has an average cross-setion of104 square inches, and weighs 7 tonnes. Unfortunately, the pillar is now in three parts.

3) Iron beams (29 of them) at the temple at Konark (near Puri) - the largest measures 35 feet by 6 inches, and the second in size, 25 feet by 6 inches. Both have a cross-section of 11 inches by 11 inches. The temple was constructed sometime around AD1240.
4) The 232 beams of the twelfth century Gundicha Bedi Temple at Puri! The longest beam is 17 feet in length, and cross-sections of the beams vary from 6 inches by 4 inches to 5 inches by 5 inches.