The Effects of Corrosion on INAA Characterizations of Brass Kettles of the Early European Contact Period in Northeastern North America

Abstract

The application of instrumental neutron activation analysis (INAA) to copper-based trade kettles found in Early European contact period archaeological sites in northeastern North America has become a rapidly expanding field of study. This paper compares the INAA data from metal, both acid-etched and digitally abraded, and surface corrosion product samples, from six fragments of a brass kettle found at Chicoutimi, a late 16th to early 17th century European contact site located in the southeastern subarctic area of Québec. Statistical as well as chemical assessments show that, relative to the metal, the different surface corrosion samples are preferentially depleted in zinc and then copper, probably by leaching and the formation of oxides and carbonates. The concentrations of minor and trace elements in the corrosion products are sometimes similar to those found in the metal, or are radically increased relative to the metal.