History of Technology in India, Vol. I: From Antiquity to c. 1200 A.D. v1.c12.s1.t13: Rampura-Agucha Mines
History of Technology in India, Vol. I: From Antiquity to c. 1200 A.D. v1.c12.s1.t13
- Language
- English
Rampura-Agucha Mines
v1.c12.s1.t13.1
Here the ancient mine workings are preferentially located at the northern limit and in the housing wall of the deposit. A piece of wood from the mine working has been carbondated at 2240 years b.p. (*Table 1*)
v1.c12.s1.t13.2
A timber recovered from 30 m depth is dated 2356 years before present. Deep workings were formed in the centre of the lode and shafts have been sunk particularly on the hangingwall side to reach the lode at depth.
v1.c12.s1.t13.3
Most of the workings of ancient age (Fig 10) so far revealed are opencast, down to contact zone, with some 30-40% extraction on one section across the width (130m) of lode, to some 15 m depth. Slag dumps occupy some 1800 sq.m. of surface area and are approximately 1 m deep. Analysis of the slag suggests that zinc oxides were being deliberately produced there some 2000 years ago.
v1.c12.s1.t13.4
There is much silver refining debris. It is guessed that silver content in the deposit worked was as high as 15%.
v1.c12.s1.t13.5
The weathered gneiss was presumably cut by wedged end chisels rather than ‘gads’... on one section of the 375 m berm on the east side of the pit, seven remains or carbonised traces of woven baskets were found (Fig.11). In the same location timber supports, with verticals morticed into sole plates have been found (Fig. 12). In other areas shafts with footholds had been sunk working almost vertical shoots of ore in a joint or possibly a shear zone... "Galleries visible seem to have been of walking height, the chisel marks in the usually soft rock clearly visible".
v1.c12.s1.t13.6
Rajasthan was a major mining province some 3000 years ago, with production on a substantial scale continuing 1200 years, under sometimes extreme technical difficulties. Smelting and silver refining were equally technically advanced. Zinc smelting was done as early as 9th century (and there are slight indications of much older origins). It was perfected as an industrial scale process around the beginning of 13th century, in all probability at Zawar. Fig. 13 shows the clay retorts scattered around the ruins of Zawar which were used for zinc smelting. The early miner located the ore and continued to assure himself that he was mining ore not waste. With poor illumination the main judgment between ore and waste would have been by the heft or “Weight”.
v1.c12.s1.t13.7
For the extraction of ore, metal tools were used in India from an early date. India had iron available for the tools about 2900 years ago (Hegde, 1981) and though a copper based tool has been reported for another area (Allchin, 1962) iron seems to have predominated as wedge tipped chisels, pointed ‘gads’ hammer pestles and draw-hoes. In hard competent rocks firesetting was widely used first to create a system of cracks which were exploited to extract the ore by chisels or ‘gads’.
v1.c12.s1.t13.8
Shallow mining or outcrop mining seems to have depended mainly on the use of hammer and ‘gad’ exploiting weaknesses exposed by weathering. Firesetting was occasionally used at shallow depth, and clearly predominated in the hard rocks unaffected by leached solutions at depth.
v1.c12.s1.t13.9
The problem of roof support at Zawar was simple as the rock is fairly uniform in quality and of high competency. At depth where the rocks are much less weathered, the arched openings are much larger than earlier higher working, and spans of flat roof are up to 20-30 m. Many pillars have been removed by retreat working, in a systematic manner, allowing the maximum depth to be achieved at the earliest with less risk or rock instability and water inflows. At Rajpura-Dariba where rock is weak, large timbers have been used to support both the wall and the roof; and stemples and props seem carefully shaped for the purpose.
v1.c12.s1.t13.10
The great depth attained at Rajpura-Dariba shows that the practical and economic system of water control had evolved. It is noticeable that on Zawar Mala, with one exception, the openings are placed well up from the floor of the valley so [Figure: to Hurda OPEN PIT line ancient pit waste tips irrigation Rampura base Agucha Tank Agucha N River Mansi to Bhilwara 0 metres 800]
v1.c12.s1.t13.11
Fig. 10. Plan of old workings at Rampura-Agucha as monsoon water does not rush in the mine. Care must also have been taken underground not to allow water to run to the bottom by the use of launders to bring water to a convenient transport point, and the use of finger stopes and discrete shafts allowed retreat from flooded sections. Most water must have been removed by hand bailing and lifting from the mine, using pots or leather bags. Animals might have been used on deep shafts for winding water.
v1.c12.s1.t13.12
Fig. 11. A woven basket
v1.c12.s1.t13.13
For ventilation usually the miners relied on natural ventilation. But there are evidences in pairs of shafts and linked finger stopes to suggest that intake and return airways were separated particularly at Zawar Mala and at Rajpura-Dariba.
v1.c12.s1.t13.14
There is clear evidence of late but still ancient mining in Zawar Mala, above the probable contemporary water table, worked by classical retreat methods, including pillar removal and the system was perhaps deliberately planned.
v1.c12.s1.t13.15
For transport of ore and material the ancients used good paths and ladderways for large number of people to move round continuously. Rope haulage system have been in use at Rajpura- Dariba, where ropes of 2.5 cm diameter have found. At Zawar mala especially systematic transport systems were developed, with well developed zig-zag paths on slopes, assisted by stone or wood steps or ladders on steeper sections. The size of the passage on the main routes would have allowed loads to be carried in baskets on the head.
v1.c12.s1.t13.16
For lighting oil lamps were used and there is evidence to show that lights in fixed positions were used at least at Zawar Mala.
v1.c12.s1.t13.17
Beneficiation process began at the fire-hole or forefield. Since good ore was notably ‘heavy’ a competent miner would sort it out into waste or ore at the site of its production. Crushing of the ore in the stone mortars and picking with hand was the common method of ore beneficiation.
v1.c12.s1.t13.18
Fig.12. Vertical supports morticed into sole plates
v1.c12.s1.t13.19
Specialists included firemen and timber men and the supervisory staff. Efficient trade and marketing of minerals/ores would have been organised nationally and internationally.