Manganese nodules and crusts were sampled from box cores collected at the Manganese Nodule Program (MANOP) site H in the Eastern Equatorial Pacific ocean. For majority of site H nodule bottoms have smooth, lustrous patches, whereas nodule tops are generally rough and dull. The top/bottom orientation of each manganese nodule was labeled during curation. Most of the nodutes studied were cut in haIf, and a 3-5 mm layer was scraped from nodule tops and bottoms. The chemical analysis was performed on both top and bottom sides as well as on the whole specimen. They were analysed at the U.S. Geological Survey, Menlo Park using instrumental neutron activation analysis with high-resolution lithium-drifted germanium detectors. This method involves the meeasurement of gamma-ray emission after proper irradiation of the samples.

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1989 NOAA-NCEI compiled the NOAA-MMS Marine Minerals Geochemical Database from journal articles, technical reports and unpublished sources from other institutions.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 2, pp. 935 of the related publication.