Scoriaceous Mn crust fragments on travertine-like nontronite deposit were retrieved near two hydrothermal vents while surveying the rift valley of the Mid-Atlantic Ridge using the diving saucer "CYANA". They have been examined with SEM and with an EDAX (X-ray energy dispersive analysis) apparatus coupled to SEM. Fifteen successive thin layers were taken from the upper surface downward. They were totally dissolved in HCl-HF-HClO4 and spiked with 232U and 228Th as yield tracers. Thin sources of purified U::and Th were prepared and counted by alpha spectrometry.

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1989 NOAA-NCEI compiled the NOAA-MMS Marine Minerals Geochemical Database from journal articles, technical reports and unpublished sources from other institutions.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.This dataset represents the digitized Table II, pp. 253 of the related publication.