Dr. Dexter Perkins received his Ph.D. from the University of Michigan in 1979. He has published over 80 papers and three books. He has had research appointments at the University of Chicago and the Universite Blaise Pascal and has been a regular faculty member in the Department of Geology and Geological Engineering at the University of North Dakota for 18 years. His current research is focused on mineral equilibria and science education reform. Dr. Kevin R. Henke received his Ph.D. in geology from the University of North Dakota in 1997. He has had research and postdoctoral appointments at Oak Ridge National Laboratory, North Dakota State University, The University of North Dakota, and the University of Kentucky. Currently he is researching the chemistry of mercury, cadmium, barium, and other heavy metal organometallic compounds.