The minor in archaeological science offered by the Museum’s Center for the Analysis of Archaeological Materials (CAAM) consists of six course units including an advanced class with an archaeological science research component as a capstone. Since it was established in 2016, over 20 students have graduated with a minor in archaeological science. Two of the six class of 2022 graduates Cole Gaboriault and Susan Zare share the research they conducted for their capstone projects.
Testing a Possible Source of Viking Iron
As my research project for the archaeometallurgy seminar, I sought to understand if a particular ore (metal-bearing rock) sampled from Hvalfjörður, Iceland was a potential source of iron for the Vikings. The ore in question was believed to be bog iron, a renewable iron ore produced by iron-oxidizing bacteria mainly in bogs and swamps. Iron Age cultures all over Europe used it extensively, and the Vikings, who settled Iceland in the late 9th century CE, were no exception. In the past, to extract metal from ores, metal smiths heated ore in the presence of charcoal so that certain chemical reactions could take place to convert minerals into metal. This process is called smelting. Thanks to its high iron content, bog iron is easier to smelt than most ores, which contributed to its widespread exploitation. I analyzed, processed, and smelted the ore sample with the help of CAAM archaeometallurgist Dr. Vanessa Workman.
First, I used several techniques to determine the structure and composition of the ore: the microstructure was observed under a reflected-light microscope; the bulk composition was measured using X-ray fluorescence; and fine structures and their compositions were measured using scanning electron microscopy equipped with energy dispersive spectroscopy. Then I processed, or beneficiated, the ore to increase its iron content and prepare it for smelting. I crushed it by hand into roughly pea-sized chunks, sorted out low-iron impurities, ground the remaining chunks into a fine powder, and sieved the powder to ensure a consistent particle size. As a last processing step, I roasted the powdered ore by heating it to 600°C (1112°F) in a small kiln, which removed excess water and caused some preliminary chemical reactions. Finally, I smelted the ore inside an electric furnace. The Vikings smelted their iron in tall, earthen furnaces called bloomeries; to mimic these conditions, I layered powdered charcoal and ore inside a graphite cup called a crucible and heated it to 1250°C (2282°F).
Upon analysis, we discovered that the ore sample had a much lower iron content than pure bog iron and contained a high percentage of non-iron-bearing impurities, or gangue, such as silica. Despite this, the smelt succeeded in producing a small quantity of metallic iron, thanks to the tightly controlled environment inside the modern electric furnace. While the Vikings may have exploited bog iron from nearby deposits, it is unlikely this particular source was smelted using Iron Age technology.
Cole Gaboriault, C22, majored in physics, linguistics, and classical studies, and minored in archaeological science and mathematics. The author stands in front of an electric furnace with the results of the crucible smelt; photo by Vanessa Workman.
Acknowledgment
The author would like to thank Steven Szewczyk, Department of Materials Science and Engineering, and the Laboratory for the Research on the Structure of Matter, for facilitating use of the electric furnace.
Researching Food Practices at Sant’aniceto, Italy
I conducted my senior research on the archaeobotanical material from Sant’Aniceto, a Final Bronze Age site in Calabria, Italy (1200–900 cal BCE). The Late Bronze Age was broadly an era of social, political, and environmental change. Settlements experienced major transitions and several, like Sant’Aniceto, were abandoned altogether. This hilltop site was excavated from 2007 to 2009, uncovering an abandoned subterranean structure filled with midden debris that included ceramics, animal bones, and plant remains. Last summer, under the mentorship of Dr. Chantel White, I identified carbonized seeds and nuts recovered from this structure using low-power microscopy in the CAAM Archaeobotany Lab. These identifications allowed me to explore subsistence strategies, diet, and local human-landscape relations at the site.
The most common finds include barley, einkorn, broad bean, and olive, and they are well attested in the region and period. Other notable finds include millet, grape, fig, common pea, acorn, and myrtle. I was able to compare this assemblage to those of other sites in southern Italy to learn more about regional systems of knowledge, exchange networks, and cultural change. In my senior thesis, I discussed the evidence of early olive cultivation, grain and legume agriculture, wild plant exploitation, and food processing. Throughout this project, I’ve been able to apply the research methods and theoretical frameworks that I learned in CAAM courses like Living World in Archaeological Science (ANTH 267/567) and Plants and Society (ANTH 440) to add to the understanding of what daily food routines may have looked like for the inhabitants of Sant’Aniceto.
Susan Zare, C22, majored in anthropology, and minored in archaeological science and classical studies. The author using a lowpowered microscope in the Archaeobotany Lab; photo by Marie-Claude Boileau.