Archaeometry

Radioactive decay (fission) of uranium U-238 causes microscopic tracks of subatomic particles to develop in minerals and glass. By measuring the number of these present in an artifact, which is a function of the sample's age and the amount of uranium present, scientists can determine the absolute age of an artifact.

Fission-track dating has been used to determine the age of glaze coverings on 400-500 year old Japanese bowls. A glass shard dating to Gallo-Roman times was determined to date from A.D. 150, but the precision of that date was only +/- 20% (a possible date range from A.D. 120–180) Nineteenth-century glass produced in central Europe, on the other hand, was dated very precisely. The technique has occasionally proven useful for pottery analysis when the objects contained inclusions of materials such as obsidian in which the fission tracks had not been erased over time by the high temperatures of glazing.