Roweite occurs as reddish to dark brown granular crystals up to 0.8 mm across in crystalline limestone near gehlenite-spurrite skarns at the Fuka mine, Okayama Prefecture, Japan. It is closely associated with uralborite. 6.011 based on O = 13. The unit cell parameters are a = 9.057(2), b = 13.335(3), c = 8.284(3) Å. The calculated density is 2.92 g cm −3 . The roweite from the Fuka mine was probably formed as a secondary mineral from calcium borates such as uralborite in a reaction with manganese-bearing late hydrothermal solution.

Priceite was found as a mass or a veinlet in crystalline limestone associated with gehlenite-spurrite skarns at the Fuka mine, Okayama Prefecture, Japan. Priceite occurs as grayish white or pale green aggregates of anhedral or prismatic crystals up to 0.5 mm in length in association with shimazakiite, sibirskite, uralborite and calcite. An electron microprobe analysis of priceite gave an empirical formula (Ca O based on O = 13. The unit cell parameters are a = 11.633(7), b = 6.977(3), c = 12.342(5) Å, β = 110.648(7)°. The calculated density is 2.486 g cm −3 . It is likely that priceite from the Fuka mine was formed as a secondary mineral by a late-hydrothermal alteration of shimazakiite at temperature between 100 and 190°C or less.

Calciborite was found as a veinlet or a mass in crystalline limestone associated with gehlenite -spurrite skarns at the Fuka mine, Okayama Prefecture, Japan. Calciborite occurs as milky white aggregates up to 1 mm in diameter with shimazakiite, fluorite, bornite and calcite. An electron microprobe analysis of calciborite gave an empirical formula (Ca 0.999 , respectively. The calciborite from the Fuka mine was probably formed by a reaction of boron -bearing fluids with limestone at a temperature between 250 and 300 °C.

<p>In order to compare the mineral chemical effects of acid rain on surface materials under the present oxygen level and the early Proterozoic or late Archean low oxygen (before the GOE) environmental conditions, artificial chemical weathering experiments using an improved Soxhlet extraction apparatus were conducted for basalt, which had already been covered on the early earth’s surface. Some dozens of polished basalt plates put in the extraction chamber were reacted to HCI, H<sub>2</sub>S0<sub>4</sub> and HN0<sub>3</sub> solutions at pH 4, and CO<sub>2</sub> saturated water, and distilled water at 50℃ for a different period of time up to 950 days in an open system. In the experiment under the low oxygen condition (5×10⁻⁴ PAL), the whole extraction apparatus was placed in the acrylic glove box, and oxygen was removed by the deoxidizer, and it was carried out in the nitrogen gas flow. The basalt was composed mainly of olivine as a phenocryst, and plagioclase, clinopyroxene, ilmenite and glass as a groundmass. The extracted sample solutions were collected, and analyzed using ICP-MS. Morphological, chemistry and altered product of each mineral surface were studied by SEM, EPMA, XRD and microscopy techniques.</p> <p>Under both the low oxygen before the GOE and the present oxygen concentration conditions, SEM images showed remarkable dissolution of olivine surface by the H<sub>2</sub>SO<sub>4</sub>, HNO<sub>3</sub> and HCl solutions. The (Mg + Fe)/Si on the olivine surface and (Na + Ca + K)/ (Al + Si) on the plagioclase surface decreased significantly with increasing experimental period. In chemistry of the extracted solutions, molar ratios of many elements such as Mg, K and Zn tend to be high in the three acidic solutions at pH 4, and low by the CO<sub>2</sub> saturated water and distilled water. The molar ratio is calculated by dividing the cumulative total mole of each extracted element by the mole of individual element in the unaltered basaltic rock. The ratios of Fe, Mg, Ni, Zn and Co near 70 pm in ionic radius are high, and reflect the dissolution from the octahedral coordination of olivine. The ratios of Ca, Na, Sm, Ce, La and Sr near 110 pm are high, and reflect the dissolution from the cavities within the framework of plagioclase. Under the low oxygen condition, major elements such as Fe and Mn, and minor ones such as Zn tend to dissolve easily in all extraction solutions. Ce and Eu in REE, and Nb, Ti, Y and Zr in HFS elements are soluble in pH 4 HCl and H<sub>2</sub>SO<sub>4</sub>, CO<sub>2</sub> saturated water and distilled water under the low oxygen condition. The results suggest that easily extracted elements under the low-oxygen condition of the early Proterozoic or late Archean influenced the evolution of continental crust, land and ocean, and may have contributed to the formation of the early Earth's surface environment.</p>

高知医療センター 1) ICT， 2) 細菌検査室， 3) 感染症科， 4) 泌尿器 科， 5) 看護局， 6) 医療技術局， 7) 薬剤局， 8) 三菱化学メディエン ス高知医療センター検査室， 9) 東邦大学医学部看護学科感染制 御学-152