Ultrafast μLIBS imaging for the multiscale mineralogical characterization of pegmatite rocks

Abstract

This article presents an innovative application of kHz regime μLIBS – Laser-Induced Breakdown Spectroscopy for generating detailed compositional maps of geological samples. The method effectively covers large areas (tens of cm²) rapidly while maintaining high lateral resolution (below 20 μm), producing some of the most extensive LIBS compositional images to date, with a size of 10 million pixels. Employing elemental-based images, we developed a direct methodology for mineral phase identification through mask-creation operations and logical relationships. This approach was successfully applied to reconstruct the mineralogical map of a Li-ore from the west-European Variscan belt, identifying 14 different mineral phases, including economically valuable ones like lepidolite, cassiterite, and columbite-group minerals. Furthermore, based on the reverse normative calculation, the chemical composition of the sample was calculated from the mineral phases previously obtained. The kHz μLIBS approach marks a significant advancement in elemental and phase imaging, especially pertinent to geological applications, providing comprehensive petro-geochemical insights, essential for a fast geological characterization.