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The Wicheeda carbonatite-hosted deposit is one of the most promising rare e...
The Wicheeda carbonatite-hosted deposit is one of the most promising rare earth element (REE) prospects in British Columbia. It is one of the three mineralized carbonatites selected for orientation studies. The main objectives of this orientation study are to determine the best size fraction in stream sediments for indicator mineral and exploration programs, and to characterize the geochemical gradients of Nb, Ta, REEs, Ba, Sr, and Th in sediments downstream of the Wicheeda carbonatite complex using Portable x-ray fluorescence (pXRF). This allows for determination of several pathfinder elements (Nb, Ta, REEs, Th, Ba, and Sr) in stream sediment samples collected downstream of this deposit. These samples are expected to contain indicator minerals derived from the carbonatite complex such as monazite, REE-bearing carbonates and fluorocarbonates, pyrochlore, columbite-(Fe), barite-celestine, and apatite. The +250µm, +125µm, and +63µm size fractions contain high concentrations of Nb, La, Ce, and Th relative to other size fractions. The +125µm fraction was chosen for systematic chemical analyses and future pathfinder element studies. There is co-variation of Nb, Ta, La, Ce, Pr, Nd, Y, and Th in the stream sediments. This reflects the presence of multiple mineral phases including pyrochlore, monazite-(Ce), REE-fluorocarbonates, and REE-carbonates. Instead of using traditional processing techniques, followed by hand-picking (as with diamond indicator minerals), we will test an automated approach following gravity ±magnetic separation. Mineralogical studies using optical microscopy, scanning electron microscopy (SEM), electron microprobe (EMP), and Quantitative Evaluation of Materials by Scanning electron microscopy (QEMSCAN) are required to identify and quantify minerals and their distributions downstream of the deposit. These will help assess geochemical and indicator minerals methods for Wicheeda-type carbonatite-hosted REE-deposit exploration.
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