The extraction method from soils by water is authorized in the Soil Contamination Law in Japan for heavy metal dissolution risk assessment. However, the applications to rocks are not accepted, although there are several kinds of rocks from which toxic heavy metals are possibly eluted. For examinations, differently from soils, rocks need to be crushed to appropriate grain size or powdered. To establish the risk assessment for rocks, we prepared the powdered and crushed (grain size: 2-1mm, 1-0.5mm, 0.5-0.25mm, < 0.25mm) sedimentary rocks, and examined the effects of grain sizes against the extractability of heavy metals (Mn, Co, Ni, Cu, Zn, Cd, Pb and U) by water.
Each heavy metal concentration in extracts from the crushed rock samples having any grain sizes was almost similar, and this result indicates that over-dissolution, which may be caused by crushing rocks to extremely smaller grains, does not arise in the extractions from the crushed samples less than 2mm. The repeatability of the extraction test was good, meaning that the mineral compositions exposing on grain surfaces crushed to less than 2mm were relatively homogeneous.
Some heavy metal concentrations in extracts from powdered rock samples were decreased compared to those from the crushed samples, and the over-dissolution could not be observed. The heavy metals once eluted from powdered rocks were inferred to be re-sorbed.

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The distribution of Mg²⁺, Mn²⁺, Fe²⁺, Co²⁺, Ni²⁺, Zn²⁺ and Ca²⁺ between FeWO₄ (ferberite), MgWO₄ (huanzalaite) and 2M aqueous chloride solutions was experimentally investigated under supercritical hydrothermal conditions of 500 to 800°C, 1 kb and 600°C, 0.5 to 2.0 kb.
The experimental results revealed that the cations were taken into solid phases (ferberite and huanzalaite) selectively in the following order:
Ni²⁺>Mg²⁺≥Fe²⁺>Mn²⁺＝Co²⁺>Zn²⁺>Ca²⁺.
The obtained partition coefficient - ion radius (PC-IR) curves mark a peak around Fe²⁺. However partition coefficients of Zn²⁺, Ni²⁺ and Mg²⁺ deviate from obtained PC-IR curves. Zn²⁺ shows a negative anomaly the same as other minerals with 6- or 8-fold sites. On the other hand, Ni²⁺ represents a positive anomaly. As for Mg²⁺, its partition coefficients locate on the estimated PC-IR curves at 500°C. However Mg²⁺ shows a positive anomaly with increasing temperature

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In order to understand the processes and mechanism for the formation of cerussite from anglesite under the existence of bicarbonate, chemical reaction of anglesite with sodium bicarbonate solution was experimentally examined. Natural anglesite grains between 1.00 and 1.18 mm in diameter were sealed in the teflon bottle which contains aqueous NaHCO₃ solution, and kept at 25, 50 and 75°C for up to 192 hours. A series of experiment with 1/900 mineral/solution weight ratio was carried out with changing temperature (25, 50 and 75°C), initial NaHCO₃ concentration (0.01, 0.05, 0.1 and 0.5 mol/l), and reaction time (4, 8, 12, 24, 96 and 192 hours). The run products were filtered by 0.20μm membrane filters, and the filtrate and residual solid were analyzed.
Regardless of the initial compositions and various conditions, the only identified reaction product was cerussite. Amount of cerussite relative to anglesite increases with the increase in temperature, initial NaHCO₃ concentration and reaction time. Cerussite develops on the surface of initial anglesite grains. The depth of cerussite layer increases with the increase in reaction time, suggesting that the reaction occurs at the interface between solid and solution. The rate of cerussite formation from anglesite for 24 hours increases with the increase of temperature and initial NaHCO₃ concentration, in the range of 1.29 x 10^-7 mol·s^-1·m^-2 for the condition of initial NaHCO₃ 0.01 mol/l-25°C and 7.63 x 10^-7 mol·s^-1·m^-2 for the condition of initial NaHCO₃ 0.5 mol/l-75°C. Thus, formation of cerussite from anglesite proceeds under the existence of bicarbonate even at low temperature.

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U-Pb age of zircon separated from the Ashio rhyolitic welded tuff　was determined, and whole-rock K-Ar ages with different alteration degrees were also dated. The U-Pb age of zircon in the least altered tuff was determined to have 10.25±0.16 Ma, and its whole-rock K-Ar age was dated at 11.3±0.4 Ma. This Miocene age seems to be the youngest among the major rhyolitic activities in the Oya-Ashio mine region; the youngest one brought up the largest amount of copper production in Japan toward the Ashio mine.

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Because the low concerning JOGMEC (Japan Oil, Gas and Metals National Corporation) was revised, JOGMEC taked over the fields of coal and geothermal energy from NEDO (New Energy and Industrial Technology Development Organization) on September, 2012. The cabinet decision was made newly on “Basic Plan on Ocean Policy” on April, 2013. One of the most important plans of the policy is “promotion of the development of energy and mineral resources”. Many projects were financially supported by the special facility of JBIC (Japan Bank for International Cooperation), which had been provided in order to respond to a strong yen from September, 2011 to March, 2013.

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