Japan Oil, Gas and Metals National Corporation (JOGMEC) and Tenke Mining Corp., which is now NGEx Resources Inc. (NGEx), jointly began the Vicuña exploration project, Vicuña JV, in November, 2004. The Vicuña JV project area is located in the Andean Cordillera straddling the border between Chile and Argentina with 240 km² area coverage. The Area has been considered to be highly prospective for porphyry copper-gold discoveries but sufficient exploration activities were not conducted.
In the Los Helados area situated in the Chilean side of the Vicuña JV project area, due to the lack of drilling work in the past, the distribution of alteration was only recognized at the time when JOGMEC entered the Vicuña JV in 2004. However, in February 2007, we began the drilling campaign after conducting geological mapping, geochemical, and geophysical exploration programs, totaling 18,000m in length 32 holes completed by June, 2011. As a result, we intercepted the mineralization that led to the discovery of what is believed to be a major porphyry copper-gold system. The copper-gold mineralized zone in Los Helados was formed by mineralization related to a dacite porphyry stock. It is also characterized by significant copper-gold mineralization generated in a hydrothermal breccia system. What porphyry copper-gold deposits have in common is the telescopic development of advanced argillic alteration, sericite alteration, intermediate argillic alteration, and potassic alteration, which spread from the surface to the underground area. Re-Os age dating of separated molybdenite from B type vein give date of 13.13+/-0.32Ma, similar to the age of the porphyry copper-gold systems in the eastern Maricunga subbelt.
Grassroots exploration in Los Helados began with geological mapping targeting the alteration identified by satellite image analysis, and after 7 years of exploration, it resulted in the discovery of a potentially significant porphyry copper-gold deposit. It can be pointed out that the following four major factors played important roles in our success in the early-stage exploration: identification of alteration through ASTER satellite image analysis, review of geological models at the drilling stage, prediction of rich mineralization using updated information, and flexible revision of the drilling plan as new results became available.

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The Shimpo-Taiyo deposit is a wolframite-bearing quartz vein that is related to granites of the Ryoke Metamorphic Belt in Central Japan, which is considered to be barren province. The major ore minerals in the deposit are wolframite, chalcopyrite, pyrrhotite, sphalerite, WS₂ component-bearing molybdenite and native bismuth. The geology around the deposit consists of roof pendants of Ryoke metamorphic rocks and late Cretaceous granite. The granite is an ilmenite-series granitic rock, which is classified into three different types, adamellite, which is distinguished as type A and type B; and granite, called type C. The granites around the deposit are garnet-bearing leucocratic coarse-grained type C granite. The wolframite quartz veins cut both type C granites and metamorphic rocks. Chemical compositions of major and trace elements of the granites show that type C is the most differentiated around the deposit. All of the fluid inclusions in the quartz from granites and ores from the deposit are liquid-rich two-phase fluid inclusions. The homogenization temperature of fluid inclusion from the granites is around 250~340 °C and that of the ore is around 260~340 °C. The average salinity is 2.4 wt% NaCl equivalent. Given the depth in which the deposits were formed, it is estimated that the filling temperature of the fluid was around 400~540 °C. Based on the geological features of the area, the mode of occurrence of mineralized veins, the chemical compositions of granite and the data from fluid inclusions, the Shimpo-Taiyo tungsten deposit is thought to have been formed by hydrothermal activity of the differentiated type C granite.

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In order to understand the processes and mechanism for carbonation of wollastonite under hydrothermal alkali condition, chemical reaction of wollastonite with sodium carbonate solution was experimentally examined. In the experiment, crashed and sieved wollastonite grains between 1.00 and 1.18 mm in diameter were sealed in the polypropylene bottle with sodium carbonate solution, and left for fixed duration in time. A series of experiment with 1/450 mineral/solution weight ratio was carried out with changing temperature (90∼170°C), concentration of sodium carbonate solution (0.01, 0.1 and 1 mol/l), and reaction time (1∼2184 hours). The run products were filtered by 0.20 mm membrane filters, and the filtrated solution and residual solid were analyzed.
In the residual solid for all runs, the one and only identified reaction product was calcite. Calcite grains grew on surfaces of initial wollastonite grains. The size of calcite grains increases with the increase of reaction time, suggesting Ostwald ripening. Residual silica layers cannot be recognized both on surfaces and in sections. Amount of calcite increases with the increase of temperature, initial Na₂CO₃ concentration and reaction time, in the range of 89.5 % calcite/total Ca (150°C-1 mol/l initial Na₂CO₃) and 9.3% (90°C-0.01 mol/l) for 2184 hours. Whereas Ca concentration in solution was undetectable, Si concentration increased with the increase of temperature, initial Na₂CO₃ concentration and reaction time. The stoichiometric relationship between the Si concentration in solution and amount of calcite indicates that dissolution of wollastonite proceeds congruently. Dissolution rate of Si from wollastonite for 24 hours increases with the increase of temperature and initial Na₂CO₃ concentration, in the range of 4.05 x 10^-8 mol·s^-1·m^-2 for the condition of initial Na₂CO₃ 0.01 mol/l-90°C and 7.49 x 10-7 mol·s^-1·m^-2 for the condition of initial Na₂CO₃ 1 mol/l-170°C. The rate of calcite formation for 24 hours is slightly higher than the dissolution rate of Si from wollastonite, suggesting that the dissolution rate of Si from wollastonite is slower than that of Ca and the rate limiting step for wollastonite carbonation is dissolution. Thus, carbonation of wollastonite proceeds easily under hydrothermal alkali condition.

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This article reports characteristics and mutual relationship of uranium mineralization in the Olympic Dam deposit, Mount Painter area and Beverley deposit in South Australia based on information obtained from an excursion after IAGOD symposium 2010, Adelaide. A large-scale of hematite breccia complex uranium mineralization including Olympic Dam occurred in Proterozoic in the east of the Gawler Craton. The Mount Painter area with basement rocks of the Adelaide Geosyncline overlying the Gawler Craton also has the hematite breccia complex uranium mineralization in Silurian although no uranium deposit has been economically mined. Sedimentation of uranium-rich clastics from the Mount Painter area in the basin formed the Cenozoic sandstone-type uranium deposit (e.g., Beverley).

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