Specimens dredged from within the summit of a volcanic seamount during an oceanographic cruise in the Eolian Island Arc (South Tyrrhenian Sea) where examined. Mineralization, which forms veins and pockets within a silty-clayey material, consists mainly of todorokite with scarce birnessite. The chemistry (Mn 48%, Fe 0.26 %, Ni 249 ppm, Co 223 ppm) and the mineralogy of the deposit are discussed; the findings, compared with data from some of the literature, suggest a hydrothermal genesis with extreme fractionations of Mn from Fe. A process explaining the anomalous Cu content (8 200 ppm) of the deposit is also suggested.

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1989 NOAA-NCEI compiled the NOAA-MMS Marine Minerals Geochemical Database from journal articles, technical reports and unpublished sources from other institutions.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: Rossi, P L; Bocchi, G; Adams, F (1980): A manganese deposit from the South Tyrrhenian region. Oceanologica Acta, 3(1), 107-114