In 1984, the U.S. Geological Survey (USGS) conducted a reconnaissance cruise L9-84-CP aboard the R/V S.P. LEE along the northern Ratak Ridge, Marshall Islands and retrieved ferromanganese crusts (Mn crusts) on the submarine slopes of seamounts. Most of the Mn-crust samples collected on this cruise had average thicknesses less than the 4-cm minimum considered necessary for economic exploitation. However Mn crusts greater than 4-cm-thick were collected on Erikub Seamount (D6), Bikar Guyot (D15), and Ratak Guyot (D18), with an extremely thick 10.0 cm crust recovered from Ratak Guyot. The samples were sectionned and geochemical analyses were separately conducted on separate layers identified in those crusts. Major and minor elements were determined by Induction Coupled Plasma Emission Spectroscopy on samples dried at 110°C. Pt, Pd, and Rh were determined by fire assay.

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1989 NOAA-NCEI compiled the NOAA-MMS Marine Minerals Geochemical Database from journal articles, technical reports and unpublished sources from other institutions.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 4, pp. 14-20 of the related publication.