Minerals and Metals in Ancient India v1.c19.s5.t3: Iron Objects
Minerals and Metals in Ancient India v1.c19.s5.t3
- Language
- English
Iron Objects
v1.c19.s5.t3.1
The most significant discovery of the period is that of iron tools and implements. These have been found in practically all the layers suggesting that the use of iron was common throughout the PGW period. However, a majority of them came from the Upper phase. In all, one hundred and thirty-five iron objects were recovered including seven pieces of iron slags and fourteen indeterminate objects. The identifiable finds comprised of fourteen kinds of objects viz, arrowhead, spearhead, shaft, pair of tongs, clamp, chisel, bar (rod), borer, needle, hook, nail, axe, knife, and bangle. One may broadly divide them into three groups: (i) Weapons, (ii) Craft tools and implements, (iii) Household objects and ornaments.
v1.c19.s5.t3.2
The presence of iron objects in such profusion (vide Table 11.1) and the discovery of furnace, slags (Table 11.2) and certain specific tools used by blacksmiths suggest that not only were iron goods manufactured at the site, but that the smelting of iron ore was also carried out here. It has been suggested that the main source of iron for PGW people of Atrañjikhera was most probably the region extending from south of Agra, to Gwalior containing rocks in which iron content is 'high'. The extensive deposits of banded haematite-quartzite found in these rocks were considered important and have been worked out on large scale by the indigenous smelters. Chemical analysis of iron shales collected from Agra-Gwalior range shows that the material contains 21.7 per cent iron, 41.9 per cent SiO₂, 14 per cent Al₂O₃, 6.3 per cent CaO, 2.3 per cent MgO. 1.4 per cent Na₂O and 6.8 per cent K₂O. O.P. Agrawal claims that this shell might have been used for iron-making at Atrañjikhera in view of the fact that SiO₂, Al₂O₃, CaO and MgO are present in the above material as well as in the finished objects and slags. (Gaur, 1983, 487-500)
v1.c19.s5.t3.3
However, the proportions of SiO₂, Al₂O₃, CaO and MgO are lower in four of the five slags (exception being slag No. 3 vide Table 11.2) compared to the raw material, and iron percentage much higher. Therefore, the raw material used must have been lot purer than the iron shale (as analysed above) to produce slag containing as high as 63-66 per cent Fe₂O₃. Alternatively it may be suggested that only No. 3 is acceptable as a representative slag.
v1.c19.s5.t3.4
Table 11.1
v1.c19.s5.t3.5
**Analysis of Iron Objects (Chemical and Spectrographic)** **from Atrañjikhera**
v1.c19.s5.t3.6
| | Samples | | | |
| | 1 | 2 | 3 | 4 |
| Fe₂O₃ | 89.36 | — | — | — |
| SiO₂ | 0.53 | 1.80 | 1.51 | 1.32 |
| Al₂O₃ | 1.33 | .82 | .96 | 1.25 |
| CaO | 0.60 | 1.31 | .82 | .73 |
| MgO | 0.12 | 0.19 | .71 | .62 |
| Cu | — | — | — | — |
| Ni | — | — | — | — |
| TiO₂ | Tr. | Tr. | — | Tr. |
| P₂O₅ | 0.33 | 0.21 | 0.18 | 0.21 |
| S | 0.08 | 0.10 | 0.09 | 0.12 |
| C | 0.33 | 0.18 | 0.26 | 0.31 |
| MnO₂ | Tr. | Tr. | Tr. | Tr. |
| Co | — | — | — | — |
| Zn | — | — | — | — |
| As | — | — | — | — |
v1.c19.s5.t3.7
Percentage Composition of Slags from Atrañjikhera
v1.c19.s5.t3.8
| | Samples | | | | |
| | Slag No. 1 | Slag No. 2 | Slag No. 3 | Slag No. 4 | Slag No.5 |
| Fe₂O₃ | 63.76 | 65.36 | 30.4 | 66.6 | 56.0 |
| SiO₂ | 29.39 | 25.34 | 57.3 | 25.6 | 30.5 |
| CaO | 0.86 | 2.41 | 8.4 | 1.3 | 2.2 |
| MgO | 0.64 | 0.97 | 0.6 | 0.2 | — |
| MnO₂ | 1.42 | Trace | Trace | — | — |
| Al₂O₃ | 3.14 | 4.76 | 3.1 | 5.0 | 4.4 |
| P₂O₅ | 0.77 | 0.69 | — | — | — |
| Total | 99.98 | 99.53 | 99.8 | 98.7 | 93.1 |
v1.c19.s5.t3.9
It seems likely that the ore was put at first along with fuel in an open circular or oval-shaped pit-like furnace, and then reduced at high temperature raised with the help of a leather bellow. The metal thus formed might have been then forged repeatedly and hammered out to be in proper shape for preparing the desired objects.
v1.c19.s5.t3.10
This iron industry must have maintained a number of black-smiths. Another important class of skilled workers would have been that of carpenters, since several items like axe, nails, clamps, chisels, and borers apparently belong to their tool-kit. The presence of arrowheads and spearheads were probably used in both war and hunting. Though the presence of cultivated wheat, rice, barley and pulses has been shown during this period, it is surprising that not a single iron implement irrevocably associated with agriculture has been found so far. The association of iron with the painted gray ware has how been attested from other sites. Atrañjikhera has yielded what is so far the earliest reported find of iron, placed stratigraphically in twelfth century BC. (Gaur 1983, 219-20)
v1.c19.s5.t3.11
There is no doubt that iron implements were being made in India since very early times, but in comparison to copper and its alloy-bronze, the use of iron started rather late. This may be so on account of the problems presented in the working of iron. It melts at a high temperature of 1537°C. The Indus Valley Culture sites have not yielded iron objects.
v1.c19.s5.t3.12
Some of the iron objects as well as slags, excavated at Atrañjikhera were examined to gain some knowledge about the metallurgy of iron in that remote period. The aims of the metallurgical analysis were to know the nature of iron used; whether it is meteoric, wrought iron, cast iron, carbon steel, alloy steel; details of metallurgical operations, nature of the ore and if possible, its location, the use of flux, metallurgical refinement, whether any slag was present in the metal or it was completely removed, working temperatures, etc.
v1.c19.s5.t3.13
Samples were taken from four iron objects: No. 1 from the upper phases and nos. 2-4 from the middle phase of the PGW stratum. All samples had some metallic core to allow taking good representative samples. The chemical analysis of these iron objects show that silica, lime, alumina, magnesia and manganese are always present in the metal, although as impurities. Silica is in the range of .53 to 1.8 per cent, lime ranges from 0.6 to 1.31 per cent, and magnesia is .12 to .7 per cent. The phosphorous oxides are ranging from .18 to .33 per cent. Sulphur is also present. Titanium is present in traces. The percentage of carbon is low. Nickel, cobalt, zinc, arsenic are all absent. (*vide* Table 11.1)
v1.c19.s5.t3.14
It is clear from the above account that the iron used for these objects was not of meteoric origin. Meteoric iron is always associated with nickel and very often cobalt. Even otherwise, it is known that the working of meteoric iron is rather difficult. Furthermore, meteoric iron is found rarely, and would never be available in sufficient quantities for general use.
v1.c19.s5.t3.15
Metallurgical examination of the four samples gave some very interesting results. Sample No. 1 was clearly a sample of wrought iron showing no pearlite formation but containing multiple slag inclusions throughout the body. The other samples showed apart from slag inclusions, lamellar and spherodized pearlite in zones near the surface and ferrite in other areas. From this examination it appears that these objects were first made of wrought iron and later on were carburized by some technique whereby the surface or the zone nearest to the surface turned into carbide. This happens when the iron object is kept on charcoal bed for a long time at high temperature. For sample 1, either it did not pass through this process or else the surface has by now completely corroded. (Gaur 1983: 487-89; 495-96)