Copper smelting and refining in the Pampa de Chaparrí, Lambayeque, Peru, ca. 1030–1180 cal AD.

This article reconstructs the smelting and refining of copper at site 256A01 in the Pampa de Chaparrí, near Batán Grande, Department of Lambayeque, Peru. Two banks of furnaces were excavated, yielding calibrated radiocarbon dates between 1030 and 1180 AD (Middle Sicán through the Early Late Sicán period). This is the first published study from South America to have recorded evidence of copper smelting slags that were fully liquid in furnaces apparently powered by blowpipes. The copper prills produced at 256A01 contained up to 5.5% arsenic, but we have found no evidence for deliberate addition of an arsenic-bearing mineral to the furnace charge. Some of the primary copper was heavily contaminated with metallic iron, which was removed by selective reoxidation on shallow ceramic crucibles. Although there were residual sulfides in the ore, no evidence of co-smelting (reaction of copper oxides with copper sulfides) was noted.