The Namosi exploration licensed area is located 30km north west of Suva (the capital city) in the Republic of Fiji Islands. This area has been recognized as a copper prospecting area for more than 30 years. The Waivaka Corridor area is located in the centre of the Namosi exploration licensed area. Nittetsu Mining Co., Ltd and Mitsubishi Materials Corporation had conducted geological, geochemical, magnetic survey on the surface in the area in 2004 and also carried out three dimensional analysis for the data of TDIP survey (electrical exploration method) which was carried out in 2001 in the same area by Metal Mining Agency of Japan(present: Japan Oil, Gas and Metals National Corporation). In addition, on the basis of the surface survey data and analysis, drilling survey program(10 holes, total drill length 3, 401.75m) was carried out in the area in 2005. The comprehensive summary is shown as follows.
(1) The geology of the Waivaka Corridor area is consisted of the Medrausucu group(middle Miocene to Pliocene) and dioritic and quartzdioritic porphyries. The Medrausucu group is mainly composed of andesitic lava, tuff and pyroclastics. The intrusive rocks of these porphyries had caused porphyry copper type mineralization in late Miocene to early Pliocene based on the data of K-Ar dating.
(2) Six prospecting areas were extracted for drilling survey, on the basis of the data and interpretation of the results which were obtained by above mentioned surface survey, such as the existence of outcrop and float with Cu oxide, distribution of Cu and Au anomalies in the soil geochemical survey, the distribution of the positive anomaly of the reduced to the pole anomalies calculated from IGRF residuals in magnetic survey and low resistivity and middle chargeability of the TDIP survey (electrical exploration method).
(3) On the basis of the drill core and microscopic observation, the copper mineralization can be characterized by the bornite-chalcopyrite mineral assemblage accompanied by strong silicification and/or quartz vein stockwork and magnetite. The copper mineralized zones mostly occurred in the dioritic porphyry intrusion and also it can be observed in the contact part between dioritic porphyry and andesitic pyroclastics. The shape of the ore body is seemed to be controlled by ENE-WSW and NE-SW trending fracture system as we had observed quartz vein stockwork on the surface of the Wainaoulo creek.
(4)From the results of drilling survey program in 2005, some remarkable copper mineralized zones were newly discovered in Wainaoulo and Wainaoulo southeast of the Waivaka Corridor area and this discovery of the copper mineralized zones sug-gests possibility of upgrading copper development potential in the Waivaka Corridor area.

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The study, which is aiming to develop a geothermal power plant less than 10MW output and consists of well survey, environmental impact survey and integrated evaluation, was conducted in the Minase area, Akita Prefecture, northern Japan in FY 2004, 2005.
Three exploratory wells were drilled and discharge tests were carried out. Environmental impact survey was carried out for one and half year. Tracers were put into a exploratory well and a recharged well and were monitored in other wells and hot springs. Resources were evaluated as being able to run a geothermal power station, generating scale of 1, 900kW from total 115 tons per hour production of steam and hot water for 15 years. After confirming quantity of resource, binary geothermal power station project was planned and its pre-feasibility study was conducted. Study results were summarized as follows.
(1) Southern part was characterized as high temperature and high permeability. N16-MS-1 has been drilled up to 1, 600 meters and recorded the maximum temperature 224.5 degree Celsius, produced 135 tons per hour totally in a 21-day discharge test. (steam: 31 tons per hours, hot water: 104 tons per hours equivalent at atmospheric pressure, well head pressure 0.104 MPaG).
(2) South western part was characterized as relatively low temperature and high permeability. N17-MS-2 has been drilled up to 1, 500 meters and recorded the maximum temperature 166.9 degree Celsius, produced 71.7 tons per hour totally in a 36-minute discharge test. (steam: 6.5 tons per hour, hot water: 65.1 tons per hour equivalent at atmospheric pressure, well head pressure 0.104 MPaG).
(3) South eastern part was characterized as high temperature and low permeability. N17-MS-3 has been drilled up to 900 meters and recorded the maximum temperature 172.2 degree Celsius. Higher temperature is expected in the deeper part.
(4) Simulations of production performance show that the maximum production rate with no attenuation for 15 years estimated as 115 tons per hour and the maximum power generation from its flow as 1, 900 kW.
(5) A capacity of power transmission line is limited up to 940 kW.
(6) Taking expenses of power line construction and scale merits for the maximum 1, 900 kW into consideration, the plan of 940 kW scale was suitable for the Minase geothermal development project. All electric power will be sold as RPS power.
(7) An assessment of the environment, which includes hot springs monitoring, tracer test, simulation of effect against other wells and hot springs, wild animals and vegetations, resulted that the study so far had not affected the environment including hot springs and the Daifuntou - the steam manifestation valley, the possibility of affecting the environment was estimated to be very low.

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A serial waterway test was conducted using four water tanks containing aquatic plants, woody biomass chips containing ferment bacilli, shell-bearing clastic rocks and zeolite rocks. The first water tank (No.1) contained Phramites australis and Scirpus tabernaemontani. The woody biomass chips in the second water tank (No.2) were made from driftwood sourced from the Tokorogawa River and also disused building wood. The shell-bearing clastic rocks in the third water tank (No.3) were collected in Akan Town in Hokkaido, and the zeolite rocks in the fourth water tank (No.4) were from Tan-no Town, Kitami City in Hokkaido.
The results of this serial waterway test can be summarized as follows:
(1) Water tank No.1 removed PO₄-P by an average of 26.3%.
(2) Water tank No.2 was particularly effective for removing NH₄-N, NO₂-N, NO₃-N and T-N, decreasing concentrations of these parameters by 52.6 to 74.1%.
(3) Water tank No.3 alleviated COD by 36.0% and nitrogen by 31.3 to 73.3%.
(4) Water tank No.4 removed approximately 31.5 to 49.9% of nitrogen.
(5) This system was well suited for the removal of PO₄-P, NH₄-N, NO₂-N, NO₃-N, T-N, BOD, COD and specifically E. coli from the river water.

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Recent geochemical and experimental studies on porphyry-type to epithermal gold mineralizations were summarized, with the objective to better understand current progresses on origin and chemical behavior of Au-Cu in magmatic-hydrothermal ore deposits. A Cu-Au-bearing oxidized source magma is generated by slab melting and/or partial melting of overlying mantle wedge which is induced by dehydration of the subducting slab or slab melt flux. The oxidized mafic magma homogenized in a lower-crust zone ascends through the crust, and subsequently forms a giant magma chamber at upper crust. Separation of high-temperature Cu-Au-S-Cl-rich fluid from the magma melt occurs in the process of magmatic differentiation, mixing with a felsic magma, decrease of lithostatic pressure and melt solidification. This fluid causes a por-phyry-type Cu-Au mineralization at temperatures below 500-400°C. Considerable amounts of Cu and Au are partitioned into the coexisting vapor phase when boiling occurs in the magmatic fluid under a low-pressure condition. Thus, the light vapor has a high potential to induce epithermal mineralization at upper zones of the porphyry-type deposits. Through the porphyry to epithermal environments, Cu dissolves as chloride complexes in hydrothermal fluids, and Au is considered to be transported by chloride and/or thio complexes in accordance with fluid pH and chlorine concentration. Precipitation of the Au and Cu could be triggered by cooling, dilution, change of redox condition and acid neutralization.

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Arsenic is a harmful metal. Therefore, ore deposits with low arsenic contents are desirable to explore and comprehension of the factor to control arsenic contents of ore is expected. As to ore samples of kuroko deposits, arsenic contents decrease with increase of iron contents, and increase with increase of copper, lead and zinc contents. In case of arsenic rich mineralization, arsenic tends to be concentrated in high grade ore of commodity metals. Meanwhile, as to the kuroko deposits generated in the back arc and the kieslager-cyprus deposits generated in the forearc, the arsenic contents of ore samples from the former is higher than those of the latter. Besides, Arsenic contents of ore samples from the Erdenet porphyry copper deposits, Mongolia are very low, where the deposits were formed by the adakitic granitoid without participation of the continental crust materials. Therefore, high arsenic contents of ore are thought to be somewhat controlled by reaction between the ore forming fluid and the continental crust materials. Moreover, the existence of pelitic rocks is thought to be a substantial factor to control the arsenic contents of ore because the kuroko deposits within pelitic rocks dominant basement show the high contents of arsenic.

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