Supplement to: Manheim, Frank T; Pratt, Richard M; McFarlin, P F (1980): Composition and origin of phosphorite deposits of the Blake Plateau. In: Bentor, Y.K. (Ed.), Marine Phosphorites - Geochemistry, Occurrence, Genesis, Society of Economic Paleontologists and Mineralogists, Special Publication, 29, 117-137, https://download.pangaea.de/reference/80812/attachments/Manheim-etal_1980.pdf