Modern scanning- and micro-analytical spectroscopy – technologies and workflow to characterise critical raw materials: A case study of the Sokli Phosphate and Rare Earth Elements deposit, Finland

• Workflow of scanning and analytical spectroscopy technologies. • Insights from HSI enabled selective sample choice for micro-XRF. • Micro-XRF effectively identified REEs and other critical elements (P, Nb, Zr) • Mineral validation through LIBS, SEM, Raman, OM-CL and XRD. This paper examines the application of advanced spectroscopic imaging techniques on drill core and thin section samples from the Sokli P-Fe-Nb-REE carbonatite deposit in Finland. Sokli holds the potential to become a major European source of multiple technology and critical metals, including P, REE, and Fe, Mn, Nb, Ta, Zr, Hf, Sr. The minerals hosting these critical elements in the deposit occur in a complex lithological and textural relationship, posing challenges for traditional core logging and geological modelling. However, modern imaging analytical technologies, such as hyperspectral- and micro-XRF core scanning, can (i) facilitate the identification of mineral species, rock types, alteration halos, (ii) enhance lithological classification for improved resource modelling and (iii) better elucidate the genesis of carbonatites. Our review study demonstrates the agility and capability of these technologies when applied to a carbonatite-hosted P and REE-deposit. We introduce a workflow for applying these technologies. Drill core samples were scanned with hyperspectral core scanning, and selected samples were then analysed using scanning micro-XRF for more detailed material characterisation. Quantitative mineralogy analysis was performed with further verification through Digital Scanning LIBS-Analytical Microscopy, Scanning Electron Microscopy, and Optical-Cathodoluminescent Microscopy.