A gravelly sand deposit at 103 m depth on the summit region of Mount Palinuro, a seamount approximately 100 km off the Italian west coast, is made up of a mixture of manganese and iron micronodules with shallow water shell debris. The manganese-rich concretions have very high Mn:Fe ratios, are deficient in minor elements and todorokite is their principal manganese oxide phase. The iron-rich concretions are almost entirely composed of smectite. The high degree of partition of manganese and iron and the mineralogical variation suggest that the micronodules probably have a hydrothermal origin. The associated shell debris contains no fossil component showing that Mount Palinuro has been volcanically active in historically recent times. This places constraints on models for the tectonism of the southern Tyrrhenian Sea.

Samples were broken up, washed with distilled water, ground to pass a 100 mesh sieve and extracted with 6N HCl.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1989 NOAA-NCEI compiled the NOAA-MMS Marine Minerals Geochemical Database from journal articles, technical reports and unpublished sources from other institutions.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: Kidd, Robert B; Armannson, H (1979): Manganese and iron micronodules from a volcanic seamount in the Tyrrhenian Sea. Journal of the Geological Society, 136(1), 71-76