Axel Muller is Professor in Mineralogy and Petrology at the Natural History Museum of the University of Oslo in Norway. He has a strong interdisciplinary geoscience career and teaches economic geology. The late Christopher Halls was awarded a PhD in Geology in 1969 from University College London. He worked as a geologist in Canada and then as a lecturer at Imperial College, London. Following retirement he became a Scientific Associate of the Natural History Museum. Ben Williamson is an Associate Professor in Applied Mineralogy at University of Exeter. His research has focused on the nature and origin or granites and associated mineralisation, and the environmental impacts of mining. He is also dedicated to teaching and inspiring the next generation of geologists.