Department of Mineralogy, Geochemistry and Salt Deposits
(Fachgebiet Mineralogie, Geochemie und Salzlagerstätten)
At the moment, the description how
XRF works is available in German only.
The text is a script for a one week course in XRF, written by Hansjörg Prohl.
One week of teaching put into the WWW gives lots of bytes - but divided into handable chapters its worth a look.
of Mineralogy, Geochemistry and Salt Deposits
Institute of Mineralogy and Mineral Resources
Technical University of Clausthal