Copper ingots, composition

TABLE 46 Composition (%) of Copper Ingots from Wadi Arabah... 

Tin bronze is another matter because, apart from rare copper ore deposits also containing tin (e.g., some of those in Cornwall), tin from a quite different source than the copper has almost always been added to copper to produce bronze. The only tin mineral that is likely to contain lead is stannite, which is not common except as a mineralogical curiosity. Tin has always been obtained in very large quantities from cassiterite, which almost never contains even a trace of lead. The tin ingots found underwater off the coast of Israel contain no lead. Our work on Cypriot Late Bronze Age bronzes indicates no perturbation away from the characteristic Cypriot lead isotope composition, even for bronzes containing 18% tin. 

Figure 12. Lead isotope compositions of copper oxhide ingot fragments from Mathiati and Skouriotissa, Cyprus. (Reproduced with permission from ref. 3. Copyright 1986 University of Birmingham.)...

Figure 13. Lead isotope compositions of copper oxhide ingots from Ayia Triadha, Crete, in relation to the lead isotope fields for ores from Cyprus and Ergani Maden, Anatolia. The fields outlined by hatched lines are not yet firmly...

We cannot yet identify the copper sources used to make the Aghia Triadha ingots, but they may have been in Anatolia. If the lead isotope data of some of the Anatolian bronzes of an earlier date is compared with with those of Aghia Triadha ingots, there are clear similarities however, the trace element compositions of these Minoan ingots are considerably different from those of the Anatolian objects. 

The technology of producing microporous condensates consists of simultaneous electron beam evaporation in vacuum of the matrix material and the addition material from two adjacent copper water-cooled crucibles up to 70mm diameter. Alternatively the evaporation from one crucible of a composite ingot (matrix + additive) and subsequent condensation of the mixed vapor flow on the substrate can be employed. The distance from the evaporators to the substrate was equal to 300-320 mm. Substrate preheating in the range of 700-1000 °C influences the degree of open porosity as shown for a representative metal oxide system in Fig. 2. 

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