From mapping to trace-element quantification: a comparative study of iron meteorites using micro-XRF, WD-XRF, p-XRF, and TXRF.

This study presents a сomparative evaluation of four X-ray fluorescence (XRF) techniques for iron meteorite characterization. Non-destructive analyses were carried out directly on solid fragments using micro-focus XRF (micro-XRF), wavelength-dispersive XRF (WD-XRF), and portable XRF (p-XRF). In contrast, total reflection XRF (TXRF) was applied as a minimally destructive method, requiring acid dissolution of small sample masses. Six iron meteorites from different chemical groups were used as test materials: Canyon Diablo, Sikhote-Alin, Elga, San Juan, Darinskoe, and Aletai. In the absence of certified reference materials for iron meteorites, standardless analysis algorithms embedded in the spectrometer software were employed, and the results were compared with published literature data. The combination of micro-XRF and WD-XRF provided complementary information: micro-XRF revealed the spatial distribution of major elements and mineral inclusions, while WD-XRF quantified light elements (Na, Mg, Al, Si, Ca) indicative of non-metallic phases. A key methodological aspect of this study was the use of micro-XRF mapping to identify homogeneous, inclusion-free areas of the metal matrix, from which subsamples were taken for TXRF analysis. WD-XRF, p-XRF, and TXRF provided consistent data for the matrix elements, with p-XRF and TXRF showing similar performance for Ni, while WD-XRF performed best for Co. Ge was quantified by both p-XRF and TXRF, with TXRF showing better agreement with literature data compared to p-XRF. Ga was detected and quantified only by TXRF. The TXRF data for Ni, Ga, and Ge were used for chemical classification using Ni-Ga and Ni-Ge diagrams, demonstrating the potential of TXRF as a proof-of-concept for first-order classification of iron meteorites.