The Anoka, Minnesota iron meteorite as parent to Hopewell meteoritic metal beads from Havana, Illinois

Abstract

Although rare among Hopewell horizon artifacts, meteoritic metal represents the most exotic raw material used during the Middle Woodland period in Eastern North America. We demonstrate that Hopewell meteoritic beads recovered from Havana, Illinois can be linked to the Anoka, Minnesota, iron, which fell as a shower of irons across the Mississippi River. The similarity in major, minor and trace element chemistry between Anoka and Havana, the presence of micrometer-sized inclusions of gamma iron in kamacite in both, and the obvious connection via the Mississippi and Illinois Rivers between Anoka and Havana point to the production of the Havana beads from a mass of the Anoka iron. Experiments strongly support the manufacture of the beads via fragmentation of schreibersite inclusions to liberate small pieces of metal. Repeated cycles of heating to temperatures of 600-700 °C followed by cold-working produced flattened metal sheets. These sheets were subsequently rolled to make the Havana beads. Recovery of the iron mass of Anoka that was used to make the beads likely occurred by local populations who were part of the Trempeleau Hopewell center, with exchange bringing it to the Havana Hopewell center, where the beads were manufactured.