REE distribution and mineralogy in the Blötberget Apatite-Iron Oxide deposit; insights from the Kalv ore body : An Integrated Study Using XCT-XRF Core Scanning, Petrography and SEM-EDS
2025
Arnover, Maria
Rare earth elements (REEs) are critical raw materials with growing demand in green technologies and limited global supply. Iron oxide-apatite (IOA) deposits can host significant REE concentrations, particularly in minerals such as fluorapatite, monazite and allanite. This study investigates the occurrence, distribution and mineral hosts of REEs in drill core BB-14-005 from the Blötberget IOA deposit, Bergslagen, Sweden. A combination of core logging, XCT-XRF scanning (Orexplore GeoCore X10), petrography and SEM-EDS was used to identify REE-bearing phases, assess their distribution in relation to lithological units and evaluate the performance of XCT-XRF scanning as a tool for visialization of REE bearing minerals in IOA deposits. Two distinct mineral assemblages were identified: (1) in magnetite-dominated massive iron ore, REEs are hosted primarily by fluorapatite and allanite; (2) in hematite-dominated banded iron ore, REEs occur in fluorapatite, monazite, allanite and minor xenotime. Elemental data from XCT-XRF scanning correlate well with assay results (R²=0.9-0.97), though the system underestimates P and Ca. 3D tomographic models highlight high-attenuation zones interpreted as REE-bearing phases. While XCT-XRF scanning was helpful in the early stages of the study for visualizing general REE distribution throughout the core, its effectiveness is limited where REEs are hosted in low-concentration phases such as fluorapatite and may significantly underestimate total REE content in such settings.
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