Mineral resources represent basic raw materials that are indispensable to industrial activities as well as to people's lives. Ensuring their stable supply has more than ever become an important challenge in the light of environmental and sustainable development issues. In order to meet this challenge, future resource policy must address the following:
1) the collection, organization and provision of basic geologic information,
2) the creation of a recycling-based society and the steady implementation of environmental preservation measures, and
3) the clarification of the roles of private and public sectors.

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In Japan, demand for copper rose dramatically during the 1950's and 60's with the economic recovery from the devastation of WW-II and remarkable industrial development. The copper industry coped with this rise in demand by expanding its smelting capacity. On the other hand, domestic copper mining declined very rapidly during the 1970's and our copper industry subsequently developed into smelting companies rather than mining.
Now, the copper smelting capacity of Japan ranks third in the world and imports 1.3 million tons of copper in concentrates amounting to 40% of the internationally traded concentrates. In order to achieve this, the Japanese companies have aggressively invested in new resources development projects in foreign countries and in 2000 we imported 862 thousand tons from these invested mines while the equity production was only 212 thousand tons. This was possible because the Japanese custom smelters have become very important for the major international mining companies with mine production exceeding their smelting capacities. Thus the major international mining companies and the Japanese custom smelters have become mutually complementary, at least for the present.
Regarding the future outlook of this industry, I believe that there are several factors that need to be seriously considered and be prepared. One is how long the above mutually complementary relations with major international copper mining companies will last, there are possibilities of these companies increasing their smelting capacity. Another is will it become possible to process primary sulfide minerals such as chalcopyrite by hydrometallurgy at the mine site, if this technologic innovation is realized, it might drastically change the position of the custom smelters. The third important factor is the decreasing trend of Japanese domestic copper consumption and increase in the developing countries, particularly east Asia.
Now, whatever the outlook, it is obvious that maintaining a stable supply of copper concentrate will be of vital importance to the Japanese copper industry. For this, exploration geologists play the leading role. Accurate evaluation of resources development projects can be made by not only geologic investigation, but judgment involving an extremely wide range of consideration including investment environment of the country, methods of mining, ore dressing, transportation of concentrates, infrastructure of the country, and many other factors. This is the true essence of the duty of an economic geologist. The fruits of the work of exploration geologists are accurate evaluation of resources. For the Japanese copper industry to develop and prosper, the future role of the Japanese exploration geologists will be extremely important indeed and, I am convinced, will be most gratifying.

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Planning methodologies have extremely developed in recent years by means of three-dimensional Block-Model Technology. Newly discovered mineral reserves are evaluated financially in good accuracy considering mining and handling operations. In this way, mining operations come to be very simplified and efficient, and metal reserve obtainable is estimated as reliable funds for investment to construction of infrastructures and other fundamental industries in developingcountries.
Environmental problems experienced in past have almost found their solutions or mitigation alternatives. Most of them depend on finacial support based reserve re-evaluation.

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We discuss the genesis of zonal distribution of Na-rich alteration minerals including Na-smectite, clinoptilolite, mordenite, analcime, and albite at the southeastern area of the Hachimantai geothermal field, northern Japan on the basis of petrographic examinations of drilled core-samples and chemical and isotope compositions of waters.
The Na-series alteration characterized by the above minerals pervades widely rocks from the Plio-Pleistocene pyroclastics (mainly Tamagawa Welded Tuff) to the Yamatsuda-Koshidomae Formation, particularly in the two areas eastward from the Kakkonda geothermal field and Toshichi hot spa. Petrographic observation suggests that the zonal distribution of Na-rich minerals excluding albite was formed by interactions of glassy rocks with descending groundwaters under ambient high geothermal gradients (15-20°C/100 m). Meanwhile, it was observed that an albite zone associated with abundant dolomite and magnesite is developed beneath the analcime zone locally in the IT-2 and 8 drillholes at the Kakkonda area. The hydrothermal solution equilibrated with these minerals, which was recovered at the depth of 1004 m of IT-2 drillhole, is characterized by higher concentrations of Na, Mg, and Cl and higher dD, δ¹⁸O, δ¹³C, and δ³⁴S values compared to low and high temperature fluids circulating within the adjacent Kakkonda geothermal field. Such specific characteristics of mineral association and water composition can be explained by mixing between descending groundwater and connate water, which is so-called "fossil seawater" trapped in the marine sediments of the Miocene Aniai Formation.

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Low-temperature hydrothermally altered basalts dredged from Southwest Indian Ridge (SWIR) near the Rodriguez Triple Junction in the Indian Ocean have been studied to document the petrological and geochemical characteristics and to compare these features with those in the upper part of IPOD/ODP Hole 504B. Dredged samples were classified into two groups of B₁-group and B₂-group on the basis of the degree of alteration. B₁-group samples are characterized by the presence of brownish to greenish clay minerals which fill veins and/or vesicles. On the other hand, B₂-group samples are characterized by the presence of yellowish clay minerals which partly to totally replace olivine phenocrysts. Electron microprobe analyses of these clay minerals indicate that brownish to greenish clay minerals in B₁-group samples are composed of celadonite, saponite, Fe-oxyhydroxide, and mixed layer of saponite-celadonite and Fe-oxyhydroxide-celadonite with various proportions and yellowish clay minerals in B₂-group samples are pure saponite. Compared to the relatively fresh samples, whole-rock chemical compositions of B₁-group and B₂-group samples are enriched in K₂O, Rb, and U. The enrichment of K₂O and Rb suggests that these elements were added to the altered basalts from low-temperature hydrothermal solutions during the forma-tion of the K-rich celadonite. On the other hand, MgO concentration of B₁-group and B₂-group are about the same as that of the relatively fresh samples, indicating that MgO is relatively immobile during the formation of the Mg-rich saponite at low-temperature. This result suggests that the low-temperature hydrothermal alteration at mid-oceanic ridge does not play an important role as an Mg sink. These petrological and geochemical features of B₁-group and B₂-group samples can be comparable to those of the upper and lower pillow zone in IPOD/ODP Hole 504B, respectively. However, the altered basalts from SWIR contain few carbonate and zeolite minerals, implying that these altered basalts dredged from the ridge axis of SWIR have not undergone the off-axis hydrothermal alteration reported by Alt et al. (1986) from IPOD/ODP Hole 504B.

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Fluid inclusions and oxygen isotopes studies reveal the hydrothermal history of quartz vein formation from the Yunosawa Stream-Shirai River conjunction (YS), Yunosawa midstream fumarole zone (YM) and Nagatozawa Stream (NT) near the Toyoha Ag-Pb-Zn deposit.
Vapor-rich primary and pseudosecondary fluid inclusions are dominant both in the YS and NT quartz samples. Some of the vapor-rich inclusions coexist with liquid-rich inclusions. The presence of these vapor-rich and liquid-rich fluid inclusions suggests that boiling occurred during quartz vein formation both at YS and NT. Homogenization temperatures and salinities of primary fluid inclusions are shown as follows:
173-178°C and 6.1-6.7 wt percent NaCl equiv. (YS)
204-251°C and 0.9-1.1 wt percent NaCl equiv. (YM)
152 to 265°C and 0.0-1.1 wt percent NaCl equiv. (NT)
Depth determinations for the inclusions with evidence of boiling are 75-79 m and 130 m below the paleowater table at YS and NT, respectively. The origin of high-salinity fluid inclusions at the YS might be a consequence of locally extreme boiling rather than the steady introduction of a deep brine.
Oxygen isotope values of vein quartz range from 3.0 to 3.4, 2.4-2.8 and 2.5-4.3 permil at YS, YM and NT, respec-tively. Combined with the fluid inclusion data, calculated oxygen isotope values of hydrothermal fluid range from -10.5 to -10.1, -7.0 to -6.5 and -10.4 to -9.6 permil at YS, YM and NT, respectively.
We interpret the data to indicate that the hydrothermal fluids responsible for quartz vein formation at YS YM and NT resulted from a mixing of meteoric groundwater with deep hydrothermal fluids. The fluids both at YS and NT consist of ascended vapor-rich fluids and steam condensates. The ratio of meteoric groundwater to deep fluids at YS and NT could be either the same as or higher than those for Toyoha earlier mineralization.
Since Pliocene (2.4Ma), quartz veins formed through episodic hydrothermal events showing variable temperature and fluid composition both at YS and YM along Yunoswa Fault. Quartz veins at NT formed through a hydrothermal event related to Toyoha's earlier mineralization.

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The groundwater of the Mobara gasfield in Boso peninsula, eastern Japan, contains considerable amount, around 100 mg/L, of iodine besides dissolved methane. Twelve groundwater samples from gas-producing wells to the aquifer within the Kazusa Group in Mobara and Naruto districts have been analyzed for iodine, pH, Eh, HCO₃-, NH₄+, SiO₂(aq), δD, δ¹⁸O, δ¹³C_CH4 and seventeen elements. There is a good correlation between the concentrations of the dissolved elements to those in marine algae. The principal source of the iodine is believed to be algae buried in the sediments and the iodine has been discharged to the porewater during decomposition of the tissue.
The molar ratio of I^-/Cl^- in the groundwater increases from 1.0×10³ to 2.2×10³ with changing the depth from 2000 to 1000 meters below the surface and turns to decrease from 2.2×10³ to 1.8×10³ with going up from 1000 to 500 meters. This tendency may be caused by the variation of buried organisms due to changing the sedimentary environment. The observed variation in the ratio indicates that the iodine discharged in the pore fluid did not migrate significantly after the deposition of the formation.

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