Methods of estimating manganese nodule grade and concentration were investigated using data from a well-explored east-central Pacific manganese nodule deposit. Bulk chemical analyses of 159 nodules recovered from 21 box cores show that the range in metal values between nodules from a single box core is commonly small but may be greater than the range in mean metal content of nodules from widely separated box cores. The metal exhibiting the greatest variability in the 21 box cores is Zn, followed in decreasing order by Cu, Mn, Co, Ni, and Fe. Approximately half of the box cores required analysis of 11 nodules or more to predict metal content within plus or minus 10 percent of the mean value.

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1989 NOAA-NCEI compiled the NOAA-MMS Marine Minerals Geochemical Database from journal articles, technical reports and unpublished sources from other institutions.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

Supplement to: Fewkes, Ronald H; McFarland, William Douglas; Reinhart, W R (1980): Evaluation of metal resources at and near proposed deep sea mine sites. United States Bureau of Mines, Open File Report, 108-80, 242 pp