X-Ray Fluorescence (XRF) spectrometry is the workhorse of whole-rock major oxide determination. However, the quality of XRF data is directly dictated by sample preparation: pressed powder pellets versus lithium borate fused glass beads.
The Mineralogical Matrix Problem
Pressed pellets retain physical mineral crystals. Hard minerals (like quartz or zircon) reflect X-rays differently from soft clays, causing significant particle size effects and matrix absorption errors. Fused glass discs completely dissolve mineral grains into a uniform, amorphous lithium borate glass bead at 1,050°C, eliminating particle size interferences and delivering true whole-rock elemental balance.