The glass jug found during a 2004 dig at the US Department of Energy’s Hanford site in Washington wasn’t your usual archaeological discovery. But, then again, Hanford isn’t your usual archaeology site.

Home to two plutonium production reactors that operated between the 1950s and 1970s, Hanford had yielded up a strange find: a safe containing a glass jug holding a clear liquid and a white slurry material.

Using a process they’ve dubbed “nuclear archaeology,” researchers at the US Pacific Northwest National Laboratory identified the substance as plutonium … but not plutonium from Hanford. Instead, using a variety of analytical techniques, they determined that material came from “the first batch of plutonium ever separated by the world’s first industrial-scale reprocessing facility in Oak Ridge, Tenn,” according to a recent issue of Analytical Chemistry.

“The analysis showed that the sample was the oldest reactor-produced plutonium collection that has been located to date,” writer Erika Gebel concludes.

Tags: plutonium