WDXRF Analysis with Borate Fusion for Small Archeological Ochre Samples

This study evaluates wavelength-dispersive X-ray fluorescence (WDXRF) for the quantification of iron and other major elements in archeological ochre, employing a borate-flux fusion technique adapted for small sample quantities. Cross-sectional microXRF mapping of glass samples fused from iron ore reference materials confirmed high compositional homogeneity for Fe, Si, K, and Ca across a broad concentration range. WDXRF calibration curves, derived from twenty certified reference materials of iron ores, facilitated the quantification of Mg, Al, Si, P, Ca, Ti, Mn, and Fe in samples with an iron content spanning 25–66 wt.%. The approach was validated via WDXRF and flame atomic absorption spectrometry (FAAS) analysis of seven archaeological ochre specimens from the Paleolithic site Kamennaya Balka II, covering the primary iron-bearing phases of goethite, jarosite, hematite, and magnetite. The agreement between WDXRF and FAAS samples confirms the accuracy of iron determination, irrespective of the iron mineral phase.