Stuart Simmons is a consulting geoscientist and a research professor who has been working on epithermal deposits, geothermal resources, and hydrothermal processes for over 30 years. Much of this effort has been directed at understanding ore-forming processes based on investigations in the geothermal systems of the Taupo Volcanic Zone and large precious metal deposits around the circum-Pacific. His published work has appeared in Economic Geology, Geology, Geothermics, Mineralium Deposita, Nature, and Science. Stuart is currently based at the Energy and Geoscience Institute at the University of Utah, where he investigates geothermal resources and critical metals in produced thermal waters in the western USA. He is former Director of the Geothermal Institute, University of Auckland, and he received his PhD in Economic Geology from the University of Minnesota.