Ferromanganese nodules were retrieved at different levels inside a core taken in the vicinity of the Hawaiian Islands. Total iron contents were determined by the bichromate method with reduction by a bismuth reducing agent. Mn total content was determined by the volumetric arsenite-nitrate method, MnO2 content was determined from the active oxygen, and the MnO content was the difference between Mn total and MnO2.

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1989 NOAA-NCEI compiled the NOAA-MMS Marine Minerals Geochemical Database from journal articles, technical reports and unpublished sources from other institutions.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.