The ferromanganese crust samples studied have been taken from Central Pacific seamount areas during the research cruise Midpac 81. Two ferromanganese crust generations with different ages have been identified; in between a period of carbonate sedimentation and an episode of phosphorite formation have taken place. The older crust generation, therefore, is mostly impregnated by carbonate-apatite. chemical concentration was determined by X-ray fluorescence (XRF) by the Geowissenschaften und Rohstoffe (BGR) on-board ship
