Chemical elements in the samples analysed were determined by atomic absorption spectrophotometry after completely dissolving the samples in a mixture of hydrofluoric, nitric and perchloric acids. The chemical data were corrected for calcium interference, and the precision of the analyses was better than ± 4% at 2 s.d. for Ca, Al, Mn, Fe and Cu, ±5% for Zn, ± 14% for Ni and ±25% for Pb. Accuracy was checked by the analysis of several international standards. Samples are distributed irregularly throughout the southwest Pacific region, the major sampling being concentrated along the island arc-trench systems, and in the North and South Fiji Basins. In addition, a number of samples from near New Zealand have been included.

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1989 NOAA-NCEI compiled the NOAA-MMS Marine Minerals Geochemical Database from journal articles, technical reports and unpublished sources from other institutions.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