During the ten R/V Hakurei-Maru cruises from 1984 through 1988 in the Northwestern Pacific island-arc area, a widespread occurrence of hydrogenetic iron-manganese crusts and nodules and hydrothermal manganese deposits were discovered. During shipboard survey, the wet iron-manganese minerals were stored with sea water in a refrigerator immediately after recovery from a sampler, in order to prevent mineralogical transformation on air drying. The subsamples, in both wet and air-dried conditions, were subjected to X-ray powder diffraction (XRD) analysis to ascertain structural stability upon dehydration. Powder samples dried at 110°C for 3 hours were analyzed for metal concentration by atomic absorption spectroscopy according to the Geological Survey of Japan (GSJ) standard analytical technique.

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1989 NOAA-NCEI compiled the NOAA-MMS Marine Minerals Geochemical Database from journal articles, technical reports and unpublished sources from other institutions.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 Tables 2 and 3, pp. 142-144, of Manheim, FT & Lane-Bostwick, CM (1989).