Discoveries of new types of marine mineral occurrences during the last decade, and specifically the massive sulfide deposits at spreading ridges on the ocean floor, have significantly advanced geologic concepts about the origin of ore deposits in a very short period of time. These discoveries also renewed interest in all marine mineral occurrences including the well-known manganese nodules, and led to more wide-ranging and thorough examination of cobalt-rich manganese crusts, expanded mapping of phosphorites of continental shelves, and the initiation of several new surveys for placer minerals in shallow waters. The result of these activities is already noticeable in an increasingly broader variety of minerals being found on and below the ocean floor. This upsurge of scientific interest and research in marine minerals provided the impetus to organize an Advanced Research Workshop under auspices of the NATO Science Council and its Special Program Panel on Marine Sciences. The workshop was held in the United Kingdom at Gregynog Hall of the University of Wales, June 10-16, 1985, under the theme "Marine Minerals--Resource Assessment Strategies. " The timing of this workshop was propitious in many ways. First, marine surveys and expeditions to chart the mineral resources of the world's oceans had increased in number in recent years, involving a growing number of nations interested in obtaining firsthand information.