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Metallurgy at Khor Rori

A significant amount of bronze and iron artefacts were found during the archaeological excavations at Sumhuram.
Together with some splendid bronze ornamental and ritual items, basins and incense burners, which were probably imported, many everyday iron and bronze tools were found, which points to local metal working and production.
The most interesting evidence is the substantial amount, about 50 kilos, of metallurgical slag, and the many small ceramic crucibles discovered in different areas of the town.
The project, conducted jointly with the Department of Geology of the University of Florence, expects to provide a general view of metal production at the site; in particular:

  • to identify what kind of metal working was developed at Sumhuram;
  • to ascertain if iron/copper smelting took place at the site or
  • if the inhabitants imported the raw metals from elsewhere to produce metallic objects locally.
The activities being conducted concern:
  • Furnaces: so far, little evidence of furnaces has come to light. The remains of only one smithing earth, located in area B, Building BB1, on the ground floor of room A73 has been discovered. It consists of a small fireplace dug into the floor to house an elongated furnace (0.75 m long, 0.44 m wide and 0.26 m deep) built in blocks of stone. The furnace was completely filled with light grey ash. Some slag was still attached to the furnace walls and abundant hammer scales were scattered around the furnace.

  • Slag and crucibles: at this preliminary stage of the research, a selected number of slag, and ceramic crucibles were sampled and analysed. Most of the slag is plano-convex from small iron smithing.
    Although further analyses could help to better identify the specific metallurgical process which this slag comes from, preliminary analyses suggest that the samples are waste products from smithing and refining/working spongy iron for the production of articles in iron. There are only few samples with Cu carbonates, and the traces of copper droplets may indicate the occasional working of polymetallic iron and copper objects.
    The most significant evidence of copper/bronze working activities are the numerous crucibles used for copper/bronze (copper-tin-lead alloys) refining and/or casting. All the crucibles are hemispherical in shape and very small. They could probably contain from 4 to 10 cm3 of molten metal for the production of small bronze articles.

  • Coins: a huge quantity of coins, more than 1200, has been discovered in the site which suggests that there was a local mint (Sumhuram is the second site of southern Arabia, after Qana in Yemen, for the number of coins). We also did a preliminary investigation on some coins that may have been minted at Sumhuram.
    The analyses are only at a preliminary stage but they seem to suggest that many different alloy compositions were used in the production of coins, from the ancient to the more recent. Moreover all coins have a detectable presence of Ni and Co deriving from a common type of mineral ore. It is possible that some crucibles, which also have evidence of Co and Ni enrichment in the metal phases, were used merely for minting.