Jennifer Smith, associate professor in the Department of Earth and Planetary Sciences at Washington University, recently found a sample of alum in the Dakhleh Oasis in the Eastern Sahara. After working with the material, she was able to link it to blue paint that was found in Egyptian pottery during the New Kingdom.

The blue in the pottery was a much paler blue than was found in many of the other blue paints from the area. Similar paints have been found across the New Kingdom, which lasted from 1550–1079 B.C.E. and spread from Egypt to the Middle East to Sudan. Therefore, archaeologists wanted to see if this sample in fact contained the same elements as the blue paint or if it was used for other purposes. Smith’s main field is geology, so she was asked to help investigate.

“I was just asked to figure out whether the material that was being mined…was something that was being mined to create the blue pigment,” Smith said. “We were really just trying to see if it was possible that the material we had in the Oasis could be used to make the blue paint.”

Archaeologists believed that this blue was made with cobalt. Looking at the samples’ chemical composition and structure at the University, Smith confirmed this assumption. She further found zinc, nickel and manganese in the sample, elements that had been found in other samples of paint.

Her findings, along with the contributions of Colin Hope and Paul Kucera, a student at Australia’s Monash University, contributed to archaeological research in the area. Many archaeologists are currently examining the trade networks in the region of the oasis. Confirming that this sample contained the same composition of the blue paint allowed them to determine whether certain trading items passed through the area.

“It was a mark of who was in contact with who in the past,” Smith said.

It also furthered archaeologists’ studies of the Dakhleh Oasis specifically.

“If our oasis was a place where you could find what was needed to make the blue paint…it was another valuable resource that they could have controlled [there],” Smith said.

Smith returns to this oasis yearly to learn more about the region and has been working there for over 10 years. She mainly works on understanding how the area has been affected by climate change and what the area was like in past periods. One particular issue that she has worked on has been to find out how humans have affected the area through exploitation of resources and migration.

“I really think that this interdisciplinary research that my team and others do trying to put together the ways that people interact with their environment in the past […] is an important thing to be doing,” Smith said.