1. Department of Geological and Atmospheric Sciences, Iowa State University, Ames, Iowa 50011–1027
2. Boliden Mines, Exploration Department, Garpenberg SE-776 98, Sweden
3. Department of Civil, Environmental and Natural Resources Engineering, Division of Geosciences, Luleå University of Technology, Luleå SE-971 87, Sweden
4. Geological Survey of Sweden, P.O. Box 670, Uppsala SE-751 28, Sweden