Manganese nodules retrieved by early cruises of the R/V Hakuho Maru in the Pacific Ocean and the R/V Umikata Maru in the Indian Ocean have been chemically analysed. Samples were dried at 300°C in order to remove volatile water components and were then treated with 3N-hydrochloric acid and a few drops of 30% hydrogen peroxide. The acid soluble part was then submitted to atomic absorption spectrophotometry to determine the composition of Mn, Fe, Ni, Cu and Co.

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1989 NOAA-NCEI compiled the NOAA-MMS Marine Minerals Geochemical Database from journal articles, technical reports and unpublished sources from other institutions.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.---Concentrations in metal are given as a percentage of the soluble part.