Abstract
Deep-sea mineral resources, such as manganese nodules, seafloor massive sulfides, cobalt-rich manganese crusts, and rare-earth element-rich deep-sea mud have been interested in as potential resources for metals near future because of their higher metal contents and no overburden removals. The R&D histories and current activities are introduced. In case of manganese nodules, three pilot mining tests at actual sites were taken place in the end of 1970s and the early 1980s. The time some pioneer environmental works were conducted simultaneously. These results still have important meanings in deep-sea mining. In the first decade of 21st century, seafloor massive sulfide mining has been focused as an immediate target for commercial mining. Currently all the deep-sea mining is considered to have higher possibilities for commercial mining because of the increasing world metal demands. Not only many states but also many venture companies are coming into the R&D arena. For the realization of deepsea mining, the durability of ore lift pipe has been the most critical technical and economic issue. On the basis of current technological progresses, the breakthrough is necessary. Japan's leadership is required for the sustainable mining good for the metal market and the environment.
