On June 10th, 1966 Mr. R.A. Ryder made, the first of his several discoveries of ferromanganese concretion occurrences in Shebandowan Lakes. On learning of these discoveries, Prof. D. S. Cronan decided to investigate the geochemistry of the deposits. Accordingly, field surveys were conducted over a nine day period in July 1970 with the assistance of the writer and scuba diver, Mr. R. R. Hygaard of Thunder Bay. A total of 50 concretion deposits, including Ryder's original discoveries, were located, described and sampled. Sampling at the concretion sites included taking bottom water and sediment core specimens as well as concretions. Additional sampling was made of waters influent into the lakes, the effluent and lake, bottom water at barren locations. Subsequently, seventy two concretion samples were analyzed by atomic absorption for Fe, Mn, K, Mg, Ca, Cu, Zn, Ni and Co at the University of Ottawa geochemistry lab. Several concretion samples were subjected to Mössbauer spectroscopy, electron spin resonance and X-ray diffraction experiments. The AA analysis of 47 water samples, and 20 sediment core samples, the former for Fe and Mn and the latter for Fe, Mn, Cu, Ni and Co was contracted commercially as was colorimetric determination of As in 10 concretion samples. Other work included logging of the sediment cores and examination of concretions through binocular microscope. This work presents field, and lab observations along with the analytical results and seeks to draw from them inferences regarding, the geochemical environment and origin of the Shebandowan Fe-Mn concretionary deposits. In early chapters basic data, general and detailed, as available on the area, has been compiled, both to aid thé current study and any future studies of the concretions and their environment. These are followed by chapters on field data and the overall interpretation.

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1989 NOAA-NCEI compiled the NOAA-MMS Marine Minerals Geochemical Database from journal articles, technical reports and unpublished sources from other institutions.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.