Wolfgang D. Maier is Professor of Economic Geology at Cardiff University, Wales, UK. He has more than 25 years of experience in the field conducting research on magmatic ore deposits. He has authored more than 100 journal papers and has been a contributing author or editor of several books, monographs, and geological maps.Raimo Lahtinen is Research Professor & Head of the Research Programme Mineral Potential for the Geological Survey of Finland. He is also an adjunct professor in bedrock geology at the University of Helsinki. His research interests include metallogeny and tectonic evolution, volcanogenic massive sulfide deposits, and the Archean-Proterozoic boundary.Hugh O'Brien is Senior Research Scientist at the Finland Geosciences Research Laboratory at the Geological Survey of Finland. He has also been a consultant for diamond exploration, and has contributed to numerous publications in geology. His research interests include radiogenic and stable isotopes applied to ore deposit studies, and kimberlites and diamonds.