48 manganese nodules from the Pacific Ocean were selected by the authors for detailed analysis. "Bulk chemical composition" gives, unless otherwise indicated, the results of X-ray fluorescence analysis of approximately one-half of the nodule illustrated. Test analyses show that analysis of such samples can be expected to be very similar to whole nodule analyses if nodules are cut into symmetrical halves. Some of the bulk analyses were run in the Department of Geology, Washington State University, by W. R. Reinhart. Others were run by outside laboratories. All results are believed to be accurate within plus or minus 10 percent of the amount present. "Weight dry (gm)" means nodule was air-dried at room temperature for one week or more. A few nodules show wet weight, meaning that they were weighed soon after removal from original plastic bags. "Morphology (i.d., shape)" is general external shape of nodule. Terms describing the "morphology" of the nodules used were selected chiefly from list in HIG Cruise Report MN-74-01. "Surface texture" is the general appearance of the nodule exterior surface.

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1989 NOAA-NCEI compiled the NOAA-MMS Marine Minerals Geochemical Database from journal articles, technical reports and unpublished sources from other institutions.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