Hematite sources and archaeological ochres from Hohokam and O’odham sites in central Arizona: an experiment in type identification and characterization

The use of ochre is a defining characteristic of populations living in the Sonoran Desert of the American Southwest. Red pigments and paints were used for craft production, bodily adornment, rock art, and in mortuary contexts. Hematite and other iron-oxides are common components of this pigment that frequently appear in the archaeological record in a variety of forms and in various stages of production. Beyond this, very little is known about these materials. This paper describes the collection of potential geological sources of ochre in the Phoenix Basin and presents a methodology for the identification of processed paints. Geological sources samples are characterized using instrumental neutron activation analysis (INAA) and compared to raw materials recovered archaeologically from the Gila River Indian Community reservation. This preliminary study indicates that iron-oxide sources can be distinguished from each other and that artifacts can be matched to these sources, revealing local procurement along the Gila River by Hohokam and O’odham artisans and continuity in use of one source from the prehistoric period to the present.

► Iron-oxide sources in the Phoenix Basin can be distinguished using INAA.
► Archaeological hematite can be matched to these sources in some cases.
► A methodology for identification of processed hematite is established.
► Local procurement and continuity in use of specific sources is demonstrated.
► More follows to clarify the effects of processing on chemical signature.