Quantitative Mineral Mapping of Drill Core Surfaces I: A Method for <i>µ</i>XRF Mineral Calculation and Mapping of Hydrothermally Altered, Fine-Grained Sedimentary Rocks from a Carlin-Type Gold Deposit

Abstract Mineral distributions can be determined in drill core samples from a Carlin-type gold deposit, using micro-X-ray fluorescence (µXRF) raster data. Micro-XRF data were collected Bruker Tornado µXRF scanner on split (~25 × 8 cm) with at spatial resolution of ~100 µm. AMICS software was used to identify mineral species data, which revealed that many individual sample spots mixtures due the fine-grained nature samples. In order estimate abundances each pixel, we linear programming (LP) approach quantified Quantification spectra completed fundamental parameters (FP) standardless approach. Results FP method compared standardized wavelength dispersive spectrometry (WDS)-XRF same showed for quantification precise (R2 values 0.98–0.97) although gave slight overestimate Fe and K an underestimate Mg abundance. Accuracy chemistry results further improved by WDS-XRF as calibration correction before calculating mineralogy LP. The LP abundance predictions Rietveld refinement X-ray diffraction (XRD) patterns powders root mean square error (RMSE) LP-predicted quantitative XRD ranges 0.91 7.15% quartz, potassium feldspar, pyrite, kaolinite, calcite, dolomite, illite. approaches outlined here demonstrates maps determine mineralogy, abundances, mineralogical textures not visible naked eye sedimentary rocks associated Au deposits. This is transferable any ore but particularly useful sedimentary-hosted deposits where gangue minerals are often fine grained difficult distinguish hand specimen.