Composition of metal from Tekkem-Depe, the late bronze age settelment in southern Turkmenistan

Yegorkov A.N., Shchetenko A.Ya.

The optical emission spectral analysis of 41 metal artifacts indicates (see table) that : 1) a great part (15 samples) of them are made formally of copper (i.e. content of each element does not exceed 1%); 2) arsenic is constantly present in metal (38 samples); 3) tin is found in a major part of samples (29) forming 2 groups with a lower content 0.01-0.9%, a natural or technical admixture (19), and with a higher content 1.9-14%, deliberately added (10).

The enhanced concentration of iron (more than 1%) in some cases is probably caused by using of chalcopyrite as principal ore that is confirmed by the composition of a slag (no. 42 in the table). It contains much iron, copper and surprisingly tin that suggests the bronze to be smelted in some cases by joint reduction of mixed oxides. Arsenic bronze (or copper) is dominant in the Late Bronze Age in Southern Turkmenistan that seems to be caused by an availability of arsenic containing ores and unfavourable market boom for tin as alloying metal.