ESR Spectroscopy and X-Ray Powder Diffractometry for Marble Provenance Determination

Abstract

The ideal method for provenance determination of marble artifacts would be simple, inexpensive, reliable, and definitive. In practice no such perfect method exists. Recent attempts to assign provenance have concentrated on analytical techniques that would not depend on subjective observations, including stable isotope analysis and trace element analysis.^1,2,3 These methods all require the destruction of a sample so that it is unavailable for further analysis; additionally, trace element compositions can be highly variable and isotope analysis technically difficult. The use of electron spin resonance (ESR) spectroscopy has been proposed as a selective, rapid, and simple method for provenance determination ^4,5, which has the advantage of being nondestructive (ignoring the fact that samples must be powdered). ESR detects the presence of unpaired electron species, either transition-metal ions or free radicals (chemical compounds with broken bonds). The technique can provide several independent parameters, mostly based on observation of trace levels of manganese. Our work extends Cordischi’s proposal that ESR spectroscopy of the Mn⁺² ion could provide information about both manganese concentration and the ratio of calcite to dolomite in a sample.⁴