Ferromanganese nodules and encrustations have been analysed for Mn, Fe, Co, Ni, Cu, Zn, Pb, Ca and Al by atomic absorption spectrophotometry. The preparation of ferromanganese—oxide samples for analysis varied according to the nature of the samples. Those covered by adhering sediment were washed clean with de—ionised water and left to dry but in some cases this treatment was not necessary. Where possible, 10 to 15 g. of sample was taken for crushing. Preliminary dessication procedure was required for ferromanganese—oxide samples, because of their tendency to absorb atmospheric moisture when in a finely divided state. After 2 ml. of 6M HCL had been added to the beakers, they were placed on a hotplate and heated gently for about 2 hours to breakdown the Mn oxides prior to the addition of the main reagents. All the elements investigated were analysed in all samples by atomic absorption spectrophotometry using a Perkin Elmer 403 spectrophotometer.

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1989 NOAA-NCEI compiled the NOAA-MMS Marine Minerals Geochemical Database from journal articles, technical reports and unpublished sources from other institutions.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 Appendix - Part 1, pp. 340-350 of the related publication. Some of the samples were omitted because already published on PANGAEA. Extra samples and chemical elements were present in the NOAA-MMS data table. The extra elements are probably coming from the thesis work of Moorby, C. A; which were not published at the time but transmitted by Cronan to NOAA-NGDC.