Mineralogical and Micromorphological Analysis of Gypsum Washes at Casa Grande National Monument

Summary

This is an abstract from the "SAA 2019: General Sessions" session, at the 84th annual meeting of the Society for American Archaeology.

The great house at Casa Grande National Monument, Arizona, occupied circa 1350-1450 CE, is a four-story Hohokam structure made of puddled earth. All of the interior surfaces are finished similarly with individual clay (illite and palygorskite) and gypsum washes. Together, these two fine-finish materials give the walls a uniquely consistent red color and sheen. The gypsum washes on the interior wall surfaces of the great house have been characterized via scanning electron microscopy (SEM) and x-ray diffraction (XRD). This paper explores the mineralogical, micromorphological, and geochemical data gathered during the course of a plaster conservation project at the monument in order to elaborate on the technology and methods involved in the production of the gypsum washes. Specific attention is paid to the weathering processes and the solubilization and precipitation mechanics of gypsum and carbonate materials. An operational chain for the gypsum washes is suggested. The archaeological gypsum samples are supplemented with experimental data on gypsum processed in different ways.

This Resource is Part of the Following Collections

• Society for American Archaeology 84th Annual Meeting, Albuquerque, NM (2019)

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Record Identifiers

Abstract Id(s): 25163