History in the mines

On a map of India, the dots are marked simply as ZD A. Those three letters stand for Zawar, Dariba and Agucha and the map appears in a report titled ‘Early Indian Metallurgy’ ~ The production of lead, silver and zinc by three millennia in northwestern India’. Dr. PT Craddock along with KTM Hedge, LK Gurjar and L Willies completed the report, first published in 2017. It details the survey, excavation and scientific study of three major mines and metal production sites in the Aravalli Hills of Rajasthan, formerly the Mewar region of Rajputana.

All three sites have very extensive remnants of mining and smelting activities that took place over three millennia, which is 3,000 years of mining history. The main minerals exploited in these mines were mixed lead-zinc sulfides. Zinc is currently the main metal mined, along with small amounts of lead and zinc.

To date, the three mines – Zawar, Dariba and Agucha – have been categorized as ‘heritage mines’ by Hindustan Zinc Ltd, now part of the Vedanta Group, and are still being mined. Dr. Paul T Craddock, Researcher Emeritus, Conservation and Scientific Research at the British Museum, London explained in a media interview in 2019: “In ancient times, the driving force behind the establishment by the Mauryans of the great mines at Agucha and Dariba was the production of silver, but at Zawar it is more likely to have been zinc oxide. In the medieval and post-medieval periods, some lead and copper was produced in Dariba, mining in Agucha had ceased altogether.

But at Zawar, zinc metal was produced through advanced high-temperature distillation processes, almost certainly the first industrial-scale production of zinc anywhere in the world.” It is certainly a first for the subcontinent and challenges the Eurocentric view of technological superiority with new scientific facts. The birth of the project to study the mines of Mewar is fascinating. The report states: “In 1980, Mr. Kenneth Bush of Zinc International, RP Kapur of HZL and PT Craddock of the British Museum met in London to discuss the feasibility of the research project into the history of zinc production at Zawar.

The British Museum Research Laboratory (later the Department of Conservation and Science) was already researching the development of copper alloys, especially brass. The Department of Archeology at MS University Baroda had a long-term interest in all aspects of scientific archeology and KTM Hegde had already researched early mining activities in the Aravallis. None of the organizations had the expertise in underground exploration and recording of early mining operations.” Dr. Craddock said: “That’s why the team of mining archaeologists from the Peak District Mining Museum were invited to get involved.

They had worked on old copper mines in Israel and copper and silver mines in Spain. L Willies brought his European experience to the Aravallis. The joint project was set up in 1982 and it was Zawar’s potential that caught our interest.” The project was completed in seven years in 1989, with four short seasons in the field and much longer sessions in laboratories and libraries in both the UK and India.

The production of zinc by distillation is described in several iatrochemical texts from the first millennium CE, and the translation of these laboratory methods into a viable commercial chemical process in the Middle Ages was a remarkable achievement. Iatrochemical refers to the use of chemicals for medicinal purposes; zinc clearly had pharmaceutical uses, known to Greeks, Romans and the various socio-religious groups on the subcontinent who were developing their own medical systems. What the report emphasized was that these Aravalli mines, in the region of Mewar, were large and complex industrial enterprises located well outside the Eurocentric areas of the Middle East, which were the source of most early technology studies.

The scale and technical sophistication of the processes depicted were quite unexpected. In the post-medieval period these mines had been abandoned or had fallen into serious disrepair; this was the beginning of the colonial era which witnessed economic and commercial subjugation leading to the decline and eventual extinction of indigenous technologies. In the 18th and 19th centuries CE this was a common occurrence all over the world. Archaeometallurgy and archeology present countless challenges to its practitioners. Dr. Craddock explained in the report that simple tasks like taking ore samples can raise questions. “As Zawar illustrated in ancient times, the potential ores zinc, silver and leader were all mined.

But what ores were actually searched for at certain stages in the mine’s history is still not known with certainty,” he said. He added that the ores found in the mines today are the ones the previous miners didn’t want! He gave the example of Agucha where the silvery minerals were removed but the zinc rich deposits were left behind. “In Zawar, for example, the silver content of the minerals left in the vast ancient galleries is low, but it may have been much higher in the ore that was removed, which once occupied a space now several meters from the current walls. is,” the statement said. report revealed.

Dr. Craddock explained the importance of establishing the smelting process in these old mines. What visitors can see today are piles of production waste that stretch for miles, often quite deep, as in Dariba. “In Zawar, the zinc smelting furnaces have survived in situ, in their original place. This is a rare event and a boon to archaeologists,” he said. In the past, archaeologists charged with investigating sites of early metal production tended to avoid slag heaps – which was a shame because this is where the process information can be found.

They focused on outbuildings, fortifications, road networks and burials. Information about the melting process lies in the rubble itself. The slag and the associated refractory fragments contain a direct and permanent record of the melting process, from which the most important operating parameters can be derived. “Heaps of slag are difficult to date; we mainly relied on carbon dating, luckily copious amounts of charcoal were usually found.

Snail itself is the main component of most heaps and a selection of three typical pieces from each layer, about 8 cm square, should suffice for scientific research. Refractory fragments are also collected, quantified and selected for study,” said Dr Craddock. At Zawar, the aim was to sample the selection of retorts and slag heaps, the nearly intact furnaces still carrying their last load of retorts; this led to their excavation in a more conventional archaeological fashion. “We could set heat regimes of refractory pieces obtained from precise locations in and around the furnace structures,” he said, essentially meaning that they could “see” the Zawar smelting process in action, even though they were in time separated by centuries.

A range of analytical methods were used, including optical microscopy, thin section petrography, scanning electron microscopy with energy dispersive X-ray analysis, X-ray diffraction and atomic absorption spectroscopy in the HZL and British Museum laboratories, as well as inductively coupled plasma atomic emission spectroscopy. Although large-scale industrial enterprises were going on in these mines, in addition to the great mines of the classical world, they previously received little recognition even in ancient times when they were in operation. Dr. Craddock said: “We wanted to expand the study of industrial technical innovation and the establishment of large-scale production beyond the usual Eurocentric view ~ the development of the zinc distillation process at Zawar is important.”

Way back in the first millennium AD, methods of producing and condensing metallic zinc were established in Zawar. The zinc oxide was probably also intended for the production of brass. Significantly, systems have been developed to collect zinc vapor as a metal on an industrial scale, based on the already existing laboratory methods. The real innovation was developing these into viable industrial processes. The mines in Zawar are said to have always been under the control of the ruling authority of Maharanas of Mewar whose capital was Chittaurgarh. It is clear that the kingdom of Mewar encouraged and supported true innovation and production on an industrial scale. There must have been hundreds, if not thousands, of oven blocks in Zawar, provided with, among other things, perforated plates with identical dimensions. It is clear that tens of thousands of these components must be made in central workshops to maximize efficiency and maintain overall control. Dr. Craddock and team reportedly stated that “we were impressed by the scale and clear systematic organization of the early operation, which was so much at odds with European descriptions of the last indigenous mining operations still taking place in 19th century India.

This surprise was all the greater because it had been assumed from the excellent state of preservation that these must be late works with the last recorded operations in the 18th and early 19th century in Zawar. Radiocarbon dates showed underground mining to be ancient; that is, the operations of the previous millennia had been conducted in a more superior manner than those of the 19th century CE. It is a true tribute to our ancestors, a historic nugget dug deep from the mines of Mewar.

(The writer is a researcher writer on history and heritage issues, and former deputy curator of Pradhanmantri Sangrahalaya)

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