Radiochemical analyses have been performed on micro-samples extracted from various surface and inside layers of manganese crusts covering basalt or volcanic breccia rocks (see, Table Annex7-B). Non manganese oxide parts consisting essentially of the surrounding carbonate sediment inlays have been separated using hydrofluoric acid. After processing the samples have been dissecated at 110 Celsius and prepared as an aliquot from which a part is used for radiometric measurements using Alpha spectrometry and the other part is used for uranium-238 and thorium-232 using co-solvant precipitation.

From 1983 until 1989 NOAA-NCEI compiled the NOAA-MMS Marine Minerals Geochemical Database from journal articles, technical reports and unpublished sources from other institutions. At the time it was the most extended data compilation on ferromanganese deposits world wide. Initially published in a proprietary format incompatible with present day standards it was jointly decided by AWI and NOAA to transcribe this legacy data into PANGAEA. This transfer is augmented by a careful checking of the original sources when available and the encoding of ancillary information (sample description, method of analysis...) not present in the NOAA-MMS database.This dataset represents the digitized Table 17, page 116 of the related publication.--It is worth noting that in this table the author has ratioed isotope concentrations (ex: 230TH/232Th) while measuring each of them using inherently different methods (ex: 230Th using Alpha spectrometry and 232Th using Wet chemistry determination). Thus these terms have been labeled as plain "ratio" rather than "activity ratio".