We would like to thank Thomas Untersweg of the Geological Survey of Austria (GBA) for fruitful discussions. We are indebted to Stephanie Neuhuber for helpful comments and remarks on an earlier version of the manuscript. For helpful insights on feldspar fading we thank Mareike Trauerstein. We also thank “Wopfinger Transportbeton” and “Bayer Elfriede Sand-und Schotterwerk” for allowing us to sample in their gravel pits. Finally we would like to thank two anonymous reviewers for giving helpful comments and thoughts on the manuscript. This project was funded by the Austrian Science Fund (FWF): P23138. the measuring process.