Resolving X-ray Peak Overlaps in Sulfide Minerals

Galena is a sulfidic mineral of the composition PbS and crystallizes in the cubic crystal system. Due to its high lead content of 86.6 wt.%, PbS is the most important lead ore, which was used in ancient times by the Egyptians, Babylonians and Romans. Like many sulfides, galena has elemental peaks (Pb M series) that directly overlap with the S K peaks in EDS spectra. The result is a broadened peak with an additional lower peak on the high energy side. In contrast, QUANTAX WDS clearly resolves the individual peaks of sulfur and lead in the corresponding spectrum. High spectral resolution at low X-ray energies is especially important when low kV has to be applied to the analysis in order to achieve high spatial resolution and low depth penetration on small mineral grains.

BSE image of a submarine, hydrothermally altered, sulfide-bearing volcanic rock (sample courtesy of Dr. Daniel J. Smith, University of Leicester, UK)
X-ray spectrum section for galena in the energy region of 2.2 - 2.6 keV showing the high spectral resolution of WDS compared to EDS