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Ancient iron-smelting site near Tambaram
 Madras Christian College Magazine, Vol. xxxviii, No.1, pp. 41-44, November, 1968
Gift Siromoney

Great strides have been made in recent years in the study of the beginnings of civilization in Tamilnad. Tamil inscriptions written in a script resembling Asoka's Brahmi script have been successfully deciphered and some of them have been placed around the second century B.C.1 Thus the beginnings of civilization in Tamilnad have been pushed back by a few centuries into the pre-Christian era. The word 'civilization', as used by anthropologists, denotes that stage in the development of man when he acquired the art of writing, erected monuments and houses, practised agriculture and had settled down. The period preceding the early Tamil inscriptions belongs to the iron age and on the basis of carbon 14 dates we can say that the iron age goes back to 700 or 900 B.C.2 If it can be established that iron age people knew writing, then the beginnings of civilization in South India will be pushed back by a few more centuries.

Chingleput district contains about 200 sites containing stone monuments of the iron age.3 These monuments are funeral monuments and are of two kinds. One is the 'stone circle', a circle of about 6 metres diameter, made up of rocks each of which has a diameter of less than a metre. The other is a dolmen made up of large slabs of semi-dressed stone supported by several rough stones. Very often a dolmen is erected at the centre of a stone circle. The dolmens and the stone circles are called megalithic monuments or megaliths (large stones). These megaliths are our earliest structures and have survived for about 2,500 years; these need to be protected as valuable monuments. The basic pattern of spanning by horizontal slabs and vertical pillars remains virtually unchanged in the temple architecture of South India. Under the dolmens that have been excavated, earthen coffins with pieces of bone have been found. Apart from bones, exquisite pottery, shell bangles and various kinds of iron implements have been found in these tombs. People belonging to the Kuruba tribe are believed to erect funeral monuments closely resembling the megaliths.4 Many a scholar has wondered whether the Kurubas of today are the descendants of the ancient race of Kurumbar who built the megaliths. It is said that Kurumbar erected 24 forts in the region around Madras5 and that Thondaimandalam was originally called Kurumba-bhoomi. One wonders whether the Sanskrit word kurumba meaning orange-coloured ore or alloy is in any way related to the Tamil word kurumba, which is spelt with a different r. In spite of the large number of megalithic sites in Chingleput district, we have as yet not found any city built by these iron age people. Some organized effort must reveal at least a few habitation-sites in this area.

Dolmen at Melkoetaiyur.

Iron slag from Melkoetaiyur.

Nozzle of a furnace from Melkoetaiyur

Opaque glass in slaggy mass from Melkoetaiyur.

Nozzles and part of a furnace from Vilangudi, Tiruchi District.

Flower-pot-shaped mould from Vilangudi, Tiruchi District.


Broken pieces of crucible from Melkoetaiyur.


The megalithic people used a great variety of iron implements ranging from horse-bits to long crowbars. Where did they get the iron from ? Did they import the implements or did they make them locally themselves? We wish to record here the discovery of a site not far from Tambaram, where iron was smelted by these iron age people. Last July, a group of American students staying here for summer studies were taken to Mahabalipuram. On the Vandalur-Kelambakkam road, the author spotted a megalith near a village called Melkoetaiyur (12° 51', 80° 9'). The students were shown round the megaliths and we started looking for iron slag or waste material. We came across a few pieces and the author made another trip to the site with Dr.K. Irwin of the Florida Presbyterian College, the director of the summer institute. During this second trip we located the precise area where iron had been smelted.

On the eastern side of the hill there is a small circular plateau of about 30 metres diameter where a snake-stone is kept by the local people for worship. The whole area is strewn with lumps of iron slag, lumps of glass in slaggy mass, pieces of opaque blue glass and broken pieces of crucible. A few pieces of these were taken home and the results of the preliminary study clearly indicate that a full-scale excavation at this site will yield valuable results. The site is apparently protected by the Archaeological Survey of India but there is no sign board there at present.

The lumps of iron slag are invariably in the shape of spherical caps. Slag must have flowed into shallow circular pits of 18 cm. diameter and 5 cm. depth. Some pieces are light but others are heavy and it is possible that iron was purified by repeated processing. A piece of thick pottery with a nozzle of 2.7 cm. diameter was found. It is likely that it is a part of a furnace with a hole for introducing blast. In this piece there is a dark-blue deposit of glass and iron on the inner side of the kiln, but not on the outside or on the outer end of the nozzle. The nozzle appears to be a kind of red earthen-ware, made apparently with a potter's wheel and then fired.

A number of broken pieces of earthen-ware crucibles were picked from the surface. None of them is red in colour and the crucibles were apparently hand-made. When the pieces are powdered one gets a black powder which is attracted by magnet. The pieces are from crucibles of different sizes and some of them must have been about 10 cm. in diameter. They are thin at the top and thick at the bottom and the thickness varies from 0.75 cm. to 2.5 cm. Dark grey coloured glassy material is found sticking on the inside of some pieces and in one case the material has rusted. Sticking to another piece, is a bit of light blue opaque glass. The outer side of these pieces of crucible are bluish-black in colour and some are covered with glass.

Lumps of slag mixed with dark blue glass were picked up along with small pieces of opaque glass ranging from light green to deep blue in colour. A preliminary chemical analysis of the glass made in our laboratories by Mr R. Sivaramakrishnan indicated presence of iron. There are some pieces which closely resemble the opaque blue glass beads found during the Arikamedu excavations and exhibited at the Government Museum, Madras. We can now say with confidence that glass was discovered in South India as a by-product in the process of iron-smelting and later used for making beads.

The only form of iron-ore that exists in this part of the country is common lateritic pebbles (Sembaarangal in Tamil). It is found scattered all over the campus at Tambaram. The iron content may be only between 20 to 30%. One of the methods of iron-smelting used during the last century by local people6 was to powder iron ore, put the pieces into a furnace made of thick clay walls, add charcoal in alternate layers and bum it using bellows. When iron reached a semi-solid form it was taken out and the impurities beaten out. Thus pure wrought iron was produced.

To harden the iron, pieces of firewood from a certain tree (Cassia auriculata or Aavaarai in Tamil) forming about 5% by weight were added to the iron and put in clay crucibles and closed. The crucibles were then placed in a furnace and a blast kept going for several hours. The slag runs out and good steel is obtained. We can safely assume that this method now called the Wootz process must have originated during the iron age itself. The quality of iron produced by the iron age people must have been quite good and the Romans are said to have imported this iron 2,000 years ago for making fine swords and cutlery.7

During the last few centuries, Salem-Trichy ore (magnetite-quartz) was used to extract iron. Last May, the author was taken to an iron-ore site by Mr J.V.Subbaraman  geologist at Dalmia Cement Factory. Near a village called Vilangudi in Tiruchi district, we saw lumps of iron slag, 5 cm. thick furnace walls and clay nozzle-holders. There were several earthenware tubes 10 cm. long with the inner diameter varying from 2 to 2.5 cm. Metallic glaze is found at one end of the tube but nothing on the inner side. These must have been nozzles through which ends of blowers were introduced. When the end got choked with slag perhaps the nozzle was replaced by a new one. One such tube was surrounded by half-baked clay. We also found a large number of flower-pot-shaped 'moulds', about 20 cm. in diameter, in the same area; but there was no sign of any megaliths in this area rich in iron-ore deposits.

More than a hundred years ago iron extracted from lateritic and magnetite ores was exported to Britain from the then Madras Presidency.8 The smelting plant at Porto Novo used the ore from South Arcot district and there were other small plants near Calicut, Salem and Tiruvannamalai. The iron produced by a British factory in India using charcoal fuel, was superior to any English iron and was used in the construction of bridges in Britain. However these small plants had to close down since they could not produce a steady supply of iron owing to lack of adequate supply of charcoal.

There is no doubt that iron was smelted in many places in Tambaram area about 2,500 years ago, for lumps of slag can be found even today near the megaliths at Guduvancheri and at Pulipakkam near Chingleput. If some new process is developed for exploiting lateritic ore, then the iron industry of Tambaram area can be re-established and Madras State have its own mini-plants for producing iron.

References:

1. I. Mahadevan, 'Tamil-Brahmi inscriptions of the Sangam age', Address given at a plenary session of the II International ConferenceSeminar of Tamil Studies, Madras, 1968, p. 32.
2. H. D. Sankalia, 'Beginning of Civilization in South India', ibid., p. 13.
3. J. N. R. Banerjee, 'Megalithic problem of Chingleput district in the light of recent exploration', Ancient India, Vol. 12, 1956, p. 22.
4. E. Thurston, Castes and Tribes of Southern India, Vol. IV, 1909, p. 169.
5. K. V. Raman, The Early History of the Madras Region, Madras, 1959, P. 5
6. M. S. Krishnan, 'Iron-ore, Iron and Steel', Bulletin of the Geological Survey of India, No. 9, Calcutta, 1954, p. 44.
7. N. R. Banerjee, The Iron Age in India, Delhi, 1965, p. 161.
8. M. S. Krishnan, op. cit., p. 92.

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