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. The younger crust generation has started to accumulate around 10 Ma ago, the growth period of the older crust layer is most likely Middle Eocene to Early Oligocene. Metal concentration was determined by Atomic Absotption Spectrophometry. For Pt a chemical pre-enrichment step (e.g. enrichment by coprecipitation with tellurium) was necessary.

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1989 NOAA-NCEI compiled the NOAA-MMS Marine Minerals Geochemical Database from journal articles, technical reports and unpublished sources from other institutions.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 1, pp. 578 of the related publication.