The iron pillar at Kodachadri in Karnataka
Propelled by scientific curiosity as well as deep interest in
Indias glorious metallurgical heritage, the present author embarked on the
adventurous journey to Kodachadri twice during the last eighteen months and undertook some
preliminary studies on the material constituting this long-neglected pillar with
from fellow-metallurgists at the Karnataka Regional Engineering College, Surathkal; and the Indira Gandhi Centre for Atomic Research (IGCAR), Kalpakkam. Results of these studies, as presented here, confirm the unanimous view of the local residents that this pillar is a product of an earlier period in indigenous iron
making, and therefore deserves a detailed and serious study by scientists and technologists devoted to Indias metallurgical heritage.
Popularly referred to as the Dwaja-Sthamba (flag-staff) of the temple, the Kodachadri iron mast or pillar has long been associated in the minds of most scientists, particularly metallurgists, with the pilgrim centre of Kollur, a town located in the plains, about 120 km north of the well-known port city of Mangalore in South Canara District of Karnataka. This temple with claims to be the original temple is associated with the killing of the dumb (mooka) demon by the lion-riding Mother Goddess in the adjoining forests, where the demon was disturbing the penance of sages and holy men devoted to the Goddess. Today Kodachadri can be reached from Kollur by jeep on a 40 km long winding and slippery mud road with many hair-pin bends, often submerged in water during the rainy season lasting from April to November. The iron flag-staff towers above the small temple (Figure 1 a) and can be sighted a few kilometers away on the road, while approaching Kodachadri. If local lore is to be believed, this flag-staff is actually the top portion of the Tri- (trident) with which the Mother Goddess nailed down the wicked demon into the bowels of the earth!
The temple top has been recently renovated, somewhat on modern lines with brick, cement and distemper (Figure 1 a, b), and a platform has been added ostensibly to stabilize the pillar, but with possible un-thought-of and undesirable interactions in due course between the cement of the platform and the iron of the pillar. Rising not less than 10 m above the ground level, with a rectangular cross-section of 8.5 cm ´ 5.8 cm and characterized by rough, serrated and slightly reddish surface (Figure 1 b) the pillar displays evidence on top for local melting, flow of melt and solidification, caused by lightning during the monsoon period. Allowing for a total height of 14 m, including the hidden portions in the platform and below the earth, the weight of this flag-staff can be estimated as about 500 kg.
A very small piece weighing a few grams only was extracted from the projecting rough surface of the pillar with the consent and cooperation of the temple priest and was later subjected to a series of modern metallographic tests at the Materials Characterization Laboratories of the Indira Gandhi Centre for Atomic Research, Kalpakkam. To the authors surprise, the X-ray examination could not reveal definite presence of any element or compound besides pure iron (Figure 2 c), while the microscopic study revealed only grains of iron (Figure 2 b) with very little pearlite (eutectoid of iron and Fe3C, i.e. iron carbide generally referred to as cementite). However, a few greyish and many rather large dark inclusions (Figure 2 a and b) were noticed and could be subjected to microhardness testing and electron microprobe analysis. While the small globular inclusions could be identified as iron silicate containing some calcium (Ca) and phosphorus (P), the bigger irregular-shaped ones consisted of only iron oxide (Fe2O3) with traces of other elements like silicon (Si), calcium (Ca) and phosphorus (P). The VHN microhardness numbers were around 140 for the iron grains, about 155 in the pearlite-cum-matrix areas, and around 165 in the dark inclusions. From image analysis, the volume fraction of all the inclusions was estimated as less than 2.0%. It was not possible to arrive at the exact volume fraction of the greyish pearlitic area, but assuming it to be around 1.0%, the carbon content of the pillar iron can be estimated as definitely less than 0.05%.
It is obvious from these preliminary investigations that the Kodachadri iron pillar is not a product of modern iron making processes. The composition of the material of the pillar, viz. less than 0.05% carbon in what looks like almost pure iron, without the usual silicon, manganese and sulphur contents one associates with modern iron and steel, and with inclusions of only iron oxide and silicate, strongly suggests age-old indigenous methods for making the so-called Adi-vasi (tribal) iron with pure iron ore and wood charcoal. The fact that this pillar has withstood the onslaught of the sun, wind and rain in living memory, and perhaps also of marine air with the Arabian Sea only 4050 km away, is proof of its high corrosion resistance, even though its surface is not as smooth and clear as that of the Delhi pillar. Acting as a lightning arrester during the rainy season, the top of the pillar seems to have melted frequently and perhaps rapidly solidified through removal of heat by iron from the pillar itself. A metallographic study of this part of the pillar is bound to yield some interesting results.
The data reported here, although from a very small piece of the pillar, point to the need for a more thorough and systematic scientific, technological and archaeo-historical study of this iron mast, towering alone in its majesty in a remote hilly and forest area of Karnataka.
ACKNOWLEDGEMENTS. I thank the authorities of the
Karnataka Regional Engineering College (KREC), Surathkal, and the Indira Gandhi Centre for
Atomic Research (IGCAR), Kalpakkam, for their interest, encouragement and assistance in
the work reported above. I
also thank Prof. N. Venkataraman, Dr K. L.
Bhat and Dr K. R. Udupa, Department of Metallurgical and Materials Engineering, KREC, Surathkal, for accompanying and assisting me during the two visits to Kollur and Kodachadri. My thanks are due to Dr Baldev Raj, Materials Group, and Dr V. S. Raghunathan, Materials Characterization Group, IGCAR, Kalpakkam, for valuable assistance in arranging for the metallographic studies reported in this paper. It is also a pleasure
to thank Dr E. S. Rajagopal and Dr A. K. Raychaudhuri, former and present Directors respectively of NPL, New Delhi for their interest, encouragement and support at all times during this study.
T. R. Anantharaman
Metals and Alloys Group,
National Physical Laboratory,
Dr K. S. Krishnan Road,
New Delhi 110 012, India