Direct Production of Tin Bronzes from Copper and Cassiterite

Abstract

In the Bronze Age several possibilities for tin bronze production were available, namely direct from copper and cassiterite ore or by alloying copper with metallic tin. Cassiterite ores from two sources, Cornwall and Schlaggenwald, were available. It has to be noted that cassiterite from Schlaggenwald contained about 25 wt. % WO₃, presumably as wolframite. For the experiments, copper was melted at 1090 °C, covered with charcoal and then cassiterite and again charcoal was added. As is known from Sn smelting, the presence of tungsten reduces the yield of Sn. Thus, in our experiments the Sn content in the bronze was reduced. It can be confirmed by these experiments that the direct production of tin bronzes from copper and cassiterite ore is possible. In the Bronze Age the negative effect of tungsten should not have played a role, because at that time only the cassiterite deposits of Cornwall were known in Europe.