Minerals and Metals in Ancient India v1.c11.s7.t4: Metallurgy of Copper Axe
Minerals and Metals in Ancient India v1.c11.s7.t4
- Language
- English
Metallurgy of Copper Axe
v1.c11.s7.t4.1
In terms of Brinell hardness, the axe of Mohenjo-Daro was 85 close to the cutting edge (the figure is much above that of mild steel), decreasing to 63 towards the middle of the blade. H.C.H. Carpenter of the Royal School of Mines suggested that it is possible that the ancient axes do not retain their original harness; it is also possible that such an axe was once harder.
v1.c11.s7.t4.2
Mackay concludes from the examination of the rejected castings that the axes of Mohenjo-Daro were cast very much in the same shape as the finished specimen that we have found, even to the curved cutting edge; these would therefore have required not only hammering to shape them, but also probably a great deal of hardening. (MCK, 594-95)
v1.c11.s7.t4.3
Silver was used more extensively than gold at Mohenjo-Daro. It was not a rare metal as in ancient Egypt or Sumer. Pending further analysis of the silver objects made by the Indus Valley people, it is not possible to say anything about the sources of the metal and the ores which were used to make it. Lucas has pointed out that silver is found in nature in three conditions — metallic, non-metallic in ores and combined with gold. Metallic silver is not likely to have been the source of the silver used at Mohenjo-Daro because it is rare now and was still rarer in the ancient times. Silver is commonly found in the form of sulphide or chloride, mined with other metals, i.e., lead, zinc or copper, but a certain amount of knowledge is necessary to reduce it to its metallic state. Silver frequently occurs in small quantities in connection with lead as argentiferous galena. Lead was by no means rare at Mohenjo-Daro, and it may be that silver was extracted from the ore of lead.
v1.c11.s7.t4.4
The main silver objects which have been found from here are silver vase which contained gold and silver jewellery, ear-rings, rings, fillets etc.
v1.c11.s7.t4.5
M.A. Hamid, Assistant Archaeological Chemist, reported as follows on the fragments of silver. One of these assayed:
v1.c11.s7.t4.6
| Silver | : | 94.52 per cent |
| Lead | : | 0.42 per cent |
| Copper | : | 3.68 per cent |
| Insolubles | : | 0.85 per cent |
| (silver chloride etc.) | | |
| | | 99.47 per cent |
v1.c11.s7.t4.7
(MS-II, 523-24)
v1.c11.s7.t4.8
Hamid attributed the presence of copper in this sample to deliberate alloying, whereas Sana Ullah suggested that the parent ore contained Ag, Pb as well as Cu. One of a number of pieces of scrap silver found in a copper vase together with a number of other vessels and tools has the following composition:
v1.c11.s7.t4.9
| Silver (present as metal) | : | 14.20 per cent |
| Silver (present as chloride) | : | 56.49 per cent |
| Chlorine (present as silver | | |
v1.c11.s7.t4.10
| chloride) | : | 18.51 per cent |
| Lead | : | 1.04 per cent |
| Copper | : | 2.28 per cent |
| Sand etc. | : | 7.48 per cent |
| **Total** | | **100.00 per cent** |
v1.c11.s7.t4.11
The percentage composition of the original alloy would therefore be:
v1.c11.s7.t4.12
| Silver | : | 95.52 per cent |
| Lead | : | 1.40 per cent |
| Copper | : | 3.08 per cent |
| **Total** | | **100.00 per cent** |
v1.c11.s7.t4.13
So from the chemical analysis of the last specimen, Sana Ullah inferred that the silver was extracted from galena which was associated with copper ore. (MCK, 599)