Archaeomagnetometry uses Earth's magnetic field to date ceramics

Researchers are utilizing archaeomagnetometry to date and authenticate ancient ceramics by analyzing the magnetic properties preserved within their minerals. When clay is heated during the firing process and subsequently cooled, ferromagnetic minerals within the material align with the Earth's magnetic field, creating a permanent record known as thermoremanent magnetization.

A team led by Yoav Vaknin at the Scripps Institution of Oceanography, part of the University of California San Diego, has identified a secondary signature that could be vital for distinguishing genuine artifacts from modern forgeries. This involves viscous remanent magnetization (VRM), a subtle magnetic memory that accumulates slowly over hundreds or thousands of years as the ceramic continues to interact with the Earth's magnetic field long after its initial production.

While forgers can replicate the appearance, shape, and glaze of ancient pottery, they cannot easily replicate this long-term magnetic accumulation. By comparing the magnetic signals in ceramics to regional curves of the Earth's historical geomagnetic variations, scientists can more accurately determine the age and authenticity of archaeological finds.