While knowing the chemical composition of an artifact is sometimes useful, it is almost never acceptable to destroy the object in the process of determining its particle content. Electron microprobe analysis is an analytical technique used to establish the chemical composition of small areas on specimens. This analysis has a high spatial resolution and sensitivity, and individual analyses are reasonably short, requiring only a minute or two in most cases. Additionally, the electron microprobe can function like a scanning electron microscope and obtain highly magnified images of a sample. Electron microprobe analysis is considered a spot analytical technique, which means compositional information is collected from only a small volume, not the entire sample. The process is well suited to study artifacts that one wishes to analyze in situ, leaving the overwhelming majority of the specimen unaltered.

We are using electron microprobe analysis to determine the chemical composition of lead shot found at known and suspected Coronado sites. The compositions of each shot are determined and then visually and graphically compared in hopes of finding that lead balls found at one Coronado site might match those found at other Coronado sites.

In 2005, we asked Electron Microprobe Lab director Ellery Frahm at the University of Minnesota ( http://probelab.geo.umn.edu/electron_microprobe.html ) to determine the compositions of five lead balls. Jonathan Damp at the Zuni Cultural Resource Enterprise (http://www.zcre.net/index.html ) provided three balls from Hawikku and one from Kyakima for analysis. We provided a lead ball from the suspected Coronado site we call Camp 23 June.

Ellery provided us a numerical dataset and a set of images generated by electron microprobe analysis. We interpreted the dataset by producing graphs useful for non-parametric comparisons. Our graphics suggest that Hawikku sample 138, a 0.48 caliber lead ball, is remarkably similar to the 0.53 caliber lead ball found at Camp 23 June.

Exploration during our second field season at Kuykendall Ruins resulted in finding three lead balls. Exploration at Hawikku in August 2006 produced additional lead balls there, also. Ten lead balls were sent to Ellery Frahm in June 2007, and he provided us with a dataset of the chemical compositions of these lead shot, as well as with images of each sample. We have added these ten 2007 test results to the five obtained in 2005 in order to generate graphical analyses of fifteen distinct lead balls. Our complete numerical dataset, sample image collection and graphical presentation of these fifteen balls, plus data on any additional balls found in the 2007 – 2008 season, will be placed on this website at the time of their publications by the New Mexico Historical Review.