2.2.4. XRF

XRF measurements were performed using Thermo Scientific™ Niton™ XL3t 970 spectrometer with a GOLDD+ detector and an Ag anode X-ray tube with a 6–50 kV voltage and up to 0.2 mA current. A mining mode with four elemental ranges and a measurement duration of 50 s each (total acquisition time of 200 s) was used to better differentiate the light elements from the heavy ones. The spectra were collected from a 3 mm diameter spot size. The acquired spectra were collected and processed using Thermo Scientific™ Niton Data Transfer (NDT™) 8.4.3 software.
