Automated mineralogy based on micro-energy-dispersive X-ray fluorescence microscopy (µ-EDXRF) applied to plutonic rock thin sections in comparison to a mineral liberation analyzer

Abstract

Abstract. Recent developments in the application of micro-energy-dispersive X-ray fluorescence spectrometry mapping (µ-EDXRF) have opened up new opportunities for fast geoscientific analyses. Acquiring spatially resolved spectral and chemical information non-destructively for large samples of up to 20 cm length provides valuable information for geoscientific interpretation. Using supervised classification of the spectral information, mineral distribution maps can be obtained. In this work, thin sections of plutonic rocks are analyzed by µ-EDXRF and classified using the supervised classification algorithm spectral angle mapper (SAM). Based on the mineral distribution maps, it is possible to obtain quantitative mineral information, i.e., to calculate the modal mineralogy, search and locate minerals of interest, and perform image analysis. The results are compared to automated mineralogy obtained from the mineral liberation analyzer (MLA) of a scanning electron microscope (SEM) and show good accordance, revealing variation resulting mostly from the limit of spatial resolution of the µ-EDXRF instrument. Taking into account the little time needed for sample preparation and measurement, this method seems suitable for fast sample overviews with valuable chemical, mineralogical and textural information. Additionally, it enables the researcher to make better and more targeted decisions for subsequent analyses.

Automated Quantitative Mineralogy Applied to Metamorphic Rocks

“…0.5 wt%, and major and minor elements can be analysed with an accuracy of 1-2 wt%. This is a large improvement compared to spectrum matching AQM platforms, which are not able to detect elements in concentrations of less than 5% [22]. Also, by obtaining the chemistry for every pixel makes the addition of new minerals to the mineral library more certain, and easily adaptable to changes in composition due to slightly different metamorphic conditions (e.g., Mg/Fe ratio dependence on pressure and especially temperature during metamorphism).…”

“…However, other areas within geosciences have so far received less attention, (but see e.g., [19][20][21]). Apart from AQM with SEM-EDX systems, AQM can also be applied with wavelength dispersive spectrometry (WDX), micro-energy-dispersive X-ray fluorescence, laser-induced breakdown spectroscopy and hyperspectral mineral analyses [22][23][24].…”

Recovering and restitution of unknown, unidentified, and unlabeled samples in laboratories using EDXRF analysis

“…The EDXRF spectrometry [1] , [2] , [3] is a non-destructive nuclear method used to characterize samples in the view of their elemental composition. EDXRF spectrometry is applicable for production quality control, ecological environment monitoring, geological surveying (including the applications of µ-EDXRF), food safety, and heritage analysis, among others [4 , 5] . The method is being used worldwide because of its robustness, fast screening, and the possibility to be used in-situ and with different matrices [6] , [7] , [8] , [9] .…”

Drill-Core Hyperspectral and Geochemical Data Integration in a Superpixel-Based Machine Learning Framework

“…Thus, the logging is always supported by other analytical techniques performed on specific and small sections of few selected samples. Optical microscopy [3], X-ray diffraction (XRD) [4], X-ray Fluorescence (XRF) [5], Scanning Electron Microscopy (SEM) [6], Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) [7] are examples of the analytical techniques employed. These analyses provide information on the model mineralogy and mineralogical texture (quantified mineralogy), geochemistry of the samples (element concentrations), amongst others.…”