http://www.sciencedaily.com/releases/20 ... 124308.htm
ScienceDaily (June 27, 2008) — A chemist of Vienna University of Technology demonstrates how chemical fingerprints of volcanic eruptions and numerous pumice lump finds from archaeological excavations illustrate relations between individual advanced civilisations in the Eastern Mediterranean. Thanks to his tests and to the provenancing of the respective pumice samples to partially far-reaching volcanic eruptions, it became possible to redefine a piece of cultural history from the second millenium B.C.
Chemical signature of pumice can identify a particular eruption.