Little is known about the abundance, distribution and origin of the precious metals in marine ferromanganese materials, although it has long been recognized that elements such as silver and gold are frequently enriched in ferromanganese nodules when compared with average crustal abundance. Relative to crustal abundance, silver is enriched in nodules by a factor of between 50 and 100, and for gold enrichment factors of between 100 and 1,000 have been found. The authors report an unusual occurrence of silver and gold in ferromanganese crusts from a back-arc setting in the south-west Pacific; to their knowledge, the first report of material of this kind.

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1989 NOAA-NCEI compiled the NOAA-MMS Marine Minerals Geochemical Database from journal articles, technical reports and unpublished sources from other institutions.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: Bolton, B R; Ostwald, J; Monzier, Michel (1986): Precious metals in ferromanganese crusts from the south-west Pacific. Nature, 320(6062), 518-520