The abundance and distribution of palladium, iridium and gold has been determined in manganese nodules from widely varying locations and geological environments within the Atlantic, Indian and Pacific Oceans. The distribution of these metals is characterized by a lack of distinct regional variations, homogeneous distribution within an individual nodule, and a lack of any correlation with variations in major and other trace elements in the nodules. Assuming that all the iridium in the manganese nodules is of extraterrestrial origin, an upper limit on the mass accretion rate of interplanetary matter to the earth is calculated to be 60 tons/day over the surface of the earth.

The nodules were crushed and reduced to a 6ne powder in a ceramic mortar and irradiated for 24 hr in a nuclear reactor and converted to chlorides.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1989 NOAA-NCEI compiled the NOAA-MMS Marine Minerals Geochemical Database from journal articles, technical reports and unpublished sources from other institutions.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: Harriss, Robert C; Crocket, J H; Stainton, M (1968): Palladium, iridium and gold in deep-sea manganese nodules. Geochimica et Cosmochimica Acta, 32(10), 1049-1056