A CLASSIFICATION OF GOETHITE MINERALS BASED ON THE MÖSSBAUER BEHAVIOUR A. GOVAERT, C. DAUWE, P. PLINKE, E. DE GRAVE and J. DE SITTER J. Phys. Colloques, 37 C6 (1976) C6-825-C6-827 DOI: 10.1051/jphyscol:19766173