The Yamada deposit of the Hishikari gold mine, in southern Kyushu, Japan, develops 1.2 km southwest of the Hishikari-Honko deposit. It is composed of the Yusen and Seisen veins. As a result of exploration of the Yusen veins that commenced in 1991 and of the Seisen veins in 1995, the Seisen veins may become a bonanza of the Hishikari mine.
The veins of the Yamada deposit can also be divided into three types. Type-I veins contain white montmorillonite and are characterized by occurrence of the rare mineral truscottite. They develop in the eastern Yusen veins (typically in the Yusen No.1 vein). Type II veins contain green montmorillonite and/or saponite. Examples are the Seisen veins, which occur in the northern part of the Yamada deposit. Type III veins develop in the southwestern Yusen veins. They are compact and contain smaller amounts of clay mineral than Type-I and Type-II veins.
The Seisen No.2 vein, a champion vein among the Type-II veins, is characterized by the dominant presence of saponite. Further, ores and electrum of this vein exhibit exceptionally high Au/Ag ratios (>4 for ores and 0.64 to 0.83 for electrum); these ratios are higher than those of other veins in the Hishikari mine. It is therefore likely that certain depositional environments were responsible for the formation of the Seisen No. 2 vein, which has many other signatures of low sulfidation Au deposits.
The Yamada vein system has three orientations with N30°E, N50°E and N70°E in descending time based on cross-cut relations. This is consistent with K-Ar ages, which range from 0.66±0.06 Ma to 1.25±0.17 Ma.

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A series of surface mapping and drilling exploration programmes have located skarn type Pb-Zn mineralization in the Pallca area of the Cordillera Huayhuash in the north-central Andes of Peru. Pb-Zn mineralization consists of sphalerite, galena, pyrrhotite, pyrite, magnetite and minor chalcopyrite hosted in clinopyroxene and garnet skarnized zones of the Cretaceous Santa and Pariahuanca Formation limestones.
Outcrops of portions of the mineralization in the Santa Formation limestone (Berlin zone) have already been reported, however, mineralization zones in the Pariahuanca Formation (Culebra zone) were newly discovered by an investigation programme for skarn-associated intrusive rocks and mineral zoning.
Mineralization is associated with 16.6 m.y. granodiorite porphyry and slightly older quartz porphyry stocks. Skarn and marble contact (marble line) zones are especially important for the Pb-Zn mineralization. Pyrrhotite and pyrite rich man-tos and lenses with Pb-Zn mineralization occur in the outer portions of the skarn zone. Au mineralization is locally encountered in the skarn zones. Mo stockwork type mineralization occurs in the quartz porphyry stock.
Analysis of geochemical composition of the stocks indicates that the granodiorite porphyry stock may have more close association with the Pb-Zn mineralization than the quartz porphyry. Also mineralization surrounding the granodiorite stock is zoned with respect to metals and style of mineralization. Pb increases and Zn and Cu decrease outward from the stock. Sulfide dissemination in skarn is dominant near the stock, sulphide replacement mantos and lenses form outer portions of skarn, while veins are most distal to the stock. Au skarns are characterized in showing rather high contents in As, Sb and Bi. Also the Au skarns show positive Eu anomaly on chondrite-normalized REE pattern, while most of the Pb-Zn skams show negative Eu anomaly.
The mineralized zones are still open in strike and depth. A total of approximately 15 million tonnes of potential ore reserve in-situ at around 10 % Zn is expected in the zones. An extensive exploration programme designed under consideration of metal zoning is being carried out.

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Epithermal ore deposits are classified into low sulfidation system (LSS) and high sulfidation system. Epithermal vein type ore deposits of LSS are formed by chemical and physical changes of hot water in the fracture zone. This paper propose the formation model of epithermal vein type ore deposits of LSS, based on the characteristics of the hydrothermal alteration in Hosokura ore deposit, other epithermal ore deposits and active geothermal areas in Japan.
Initial hydrogeology of the hydrothermal system is composed of permeable near-surface aquifer of cold groundwater and permeable fracture zone in impermeable hydrogeologic basement. Neutral pH hot water rises along the fracture zone and flows into near-surface aquifer. This hot water mixes with cold groundwater at the near-surface aquifer leading to deposition of ore minerals within the aquifer and the fracture zone below it due to temperature drop (about 250°C→200°C). The hot water forms large scale neutral hydrothermal alteration zone also along aquifer.
Near-surface aquifer partly changes into horizontal and impermeable "alteration cap rock (ACR)" by hydrothermal alteration. Under this ACR, hot water comes to the boil in the fracture zone and ore minerals deposit in the fracture due to gas (H₂S, CO₂) escape and subsequent change of pH. Steam and gas are separated from hot water and rise through near-surface aquifer. Oxdation of H₂S forms acid hot water to form a small-scale acid hydrothermal alteration zone over a large scale neutral one.
The bonanza is formed where temperature of hot water falls and hot water boils, with the upper limit of it being controled by near-surface aquifer.

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The Metal Mining Agency of Japan (MMAJ) owns two research vessels that are Hakurei-maru and Hakurei-maru No.2. Since 1975, MMAJ has been surveying deepsea manganese nodules, cobalt rich crust and hydrothermal polymetalic deposits. Japan has got exclusive mining claimes for manganese nodules covering 75, 000 squar kilometers off Hawaii on. December 1987 under the United Nations Convention on the Law of the Sea.
Compared with land base mineral resources, there are huge amounts of untapped mineral resources on the deepsea floor. But only several small parts of sea floor are explored and searched. MMAJ has been carrying out exploration and research on these resources not only for present but also for future generation. In this paper deepsea mineral resources and research vessels will be introduced.

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