MetalAge is a research project financed by FCT - EXPL/EPH-ARQ/1015/2013

The goal of project MetalAge is to determine the feasibility of using the 238U natural radioactive series to date metallic artefacts. To the present date there is no implemented analytical method that can be directly applied to determine how long ago were metal artefacts fabricated. Such a method would be of high importance to place into context various archaeological finds, to study the introduction/development of metal technological solutions or even to distinguish fake objects from original ones.

To date metal artefacts which are no more than a few thousand years old, only a small part of this series, the 230Th decay to 226Ra will be considered, based on an isotopic fractionation that may occur during ore smelting, disrupting the secular equilibrium in the 238U series. To explore/validate this dating method alpha-spectrometry and analyses by SEMEDS, XRD, PIXE and RBS will be performed on materials obtained from recent smelting experiments simulating ancient and traditional technologies, as well as on coins from different chronological periods.

Experimental validation:

- determine homogeneity and fractionation efficiency of U and Th daughter products during smelting between slag and metal.

- determine statistical significance obtained taking into account the extremely low counting rates associated with measuring natural radioactivity

J. Cruz, E. Figueiredo, V. Corregidor, P.I. Girginov, L.C. Alves, C. Cruz, R.J.C. Silva and I. Liritzis, “First results on radiometric dating of metals by alpha spectrometry”, Microchemical Journal 124 (2016) 608-614 (doi:10.1016/j.microc.2015.10.001).