The University of Arizona

Radiocarbon Concentrations of Wood Ash Calcite: Potential for Dating

Lior Regev, Eileen Eckmeier, Eugenia Mintz, Steve Weiner, Elisabetta Boaretto


Ash is formed when plant calcium oxalate crystals (CaC2O4) decompose to form calcite (CaCO3). We found that ash does retain the original calcium oxalate radiocarbon concentration, but in addition, there is another minor 14C source. This is shown by the presence of a consistent small shift in the pMC and δ13C levels when comparing cellulose and ash from modern and archaeological woods. Possible mechanisms for 14C exchange during combustion or due to diagenesis are considered in order to define parameters for identifying better-preserved wood ash samples.

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