CALCOLITHIC COPPERS OF PERU

The present work describes the origin and description through metallog raphic characterization of different objects: tools and weapons found in an archeological deposits in Batan Grande near Piura in Peru. The c omprehensive available literature reviewed indicates that the base met al was reduced at low temperature with charcoal, starting from oxidize d indigenous ores to which later, during its processing, other ores of an arsenical nature coming from distant places were added. The ore de posit was named Huaca after the burial of some principal local charact er of the time. This Huaca deposit has been chronologically assigned t o the Calcolithic Age, before the American Bronze Age. The copper allo ys found were of the arsenical type. These alloys could be melted and cast at low temperature because of the attractive effect of arsenic ad ditions to copper. Arsenic also plays an important role in the solid-s olution strengthening of copper, although, to some extent, it impairs other desired mechanical properties, such as toughness. The as-cast pr eforms were further strengthen by work hardening during cold deformati on operations to sharpen cutting edges and other thin sections. The al loys of low As content normally had sufficient toughness. The use of t hese primitive copper alloys overlaps in time with those in the Americ an Bronze Age (1000 A.D.), producing cleaner and, therefore, better ar tifacts through their more advanced processing techniques. (C) Elsevie r Science Inc., 1998.