Identifying American native and European smelted coppers with pXRF: a case study of artifacts from the Upper Great Lakes region

Abstract

In North America, it is critical for archaeologists to differentiate between American native copper and European smelted copper. Indeed, native copper, a rather pure metal, was not smelted in this region, unlike European copper objects that later became available to Native Americans during trading encounters. Until now, archaeologists with a low budget wishing to use a totally non-invasive approach have relied on visual inspection and archaeological contextualization of the objects to distinguish American native copper from European smelted copper. This paper assesses the reliability of portable x-ray fluorescence (pXRF) as a fast, effective, and completely non-destructive method of differentiating the two types of copper present at Northern American sites through a case study of two sites from the Upper Great Lakes region. To establish group attribution with pXRF, results obtained on a subset of objects with LA-ICP-MS are used. Results indicate that for the specific purpose of differentiation between native and European copper types, pXRF can be used reliably, without sample preparation and despite surface corrosion. Therefore, pXRF provides a non-destructive way to clarify European trade item distribution and continuity of native copper object use among Indigenous peoples of North America during the colonial period.