Mineralogical Journal
Online ISSN : 1881-4174
Print ISSN : 0544-2540
ISSN-L : 0544-2540
4 巻, 4 号
選択された号の論文の4件中1~4を表示しています
  • TADASHI MUTO
    1965 年 4 巻 4 号 p. 245-274
    発行日: 1965年
    公開日: 2008/03/18
    ジャーナル フリー
    The solubilities of ningyoite, autunite, and hydrogen-autunite, all synthetic except autunite, were measured mainly at 25° and 100°C by immersing them in water with pH ranging from 0 to 6. Equilibrium constants of the dissolution reactions of the minerals were obtained by estimating activities of the concerning ions with the aid of the Debye-Hückel limiting law from the uranium concentrations and the pH values of the solutions. The standard free energies of formation of the minerals were then calculated from the equilibrium constants. The values are -948 Kcal for ningyoite CaU(PO4)2•2H2O, -1728 Kcal for autunite Ca(UO2)2(PO4)2•10H2O, and -1598 Kcal for hydrogen-autunite H2(UO2)2(PO4)2•10H2O with probable errors of ±2 Kcal. The standard enthalpy of formation of ningyoite was evaluated to be -1035 ±5 Kcal from the equilibrium constants at 25° and 100°C.
    Stability fields of some uranium minerals in the forms of oxide, carbonate, sulphate, and uranate in addition to the three minerals were considered in Eh-pH diagrams constructed by using the above free energy values together with the available values of the relating compounds and ions. Stability of ningyoite in comparison with uraninite was estimated by examining chemical equilibria of some reactions including them. Ningyoite stably precipitates at lower temperatures around 25°C under neutral or acidic conditions with phosphorus activity around or above 10-8, which seems to be similar to that in supergenic waters, while at higher temperatures around 100°C, only under weakly or moderately acidic conditions with high phosphorus activity around or above 2×10-7. The conditions of the ore solution in the uranium deposits around the Ningyô-tôgé area were discussed by examining equilibrium relations among the paragenetically occurring minerals including ningyoite. The reason why ningyoite has never been found in other uranium ores with high phosphorus content, e. g. phosphorite, is explained from the limitation on pH and temperature for the formation of the mineral.
  • RYOICHI SADANAGA, MASAAKI OHMASA, NOBUO MORIMOTO
    1965 年 4 巻 4 号 p. 275-290
    発行日: 1965年
    公開日: 2008/03/18
    ジャーナル フリー
    The crystal structure of β-chalcocite was determined by employing the X-ray diffraction data taken at 144°C. From its three-dimensional distribution of electron density, it was concluded that copper ions are distributed in the structure among several sites in the interstices of the array of sulphurions in hexagonal closest-packing. This conclusion is in good agreement with the recent study on the same structure made by Buerger and Wuensch. Two dimensional projections of electron density in the crystal were also worked out at four different temperatures. The statistical distribution of copper ions revealed in these experimental results is explained by an assumption that these ions travel via sites at which they form s-p hybrid covalent bonds with the neighbouring sulphur ions.
  • J. D. H. DONNAY, HIROSHI TAKEDA
    1965 年 4 巻 4 号 p. 291-298
    発行日: 1965年
    公開日: 2008/03/18
    ジャーナル フリー
    The system of the crystal-form names according to the proposal of the Fedorov Institute is explained, and adequate Japanese equivalents are given.
  • JUN ITO
    1965 年 4 巻 4 号 p. 299-316
    発行日: 1965年
    公開日: 2008/03/18
    ジャーナル フリー
    Haradaite, a new strontium vanadyl silicate SrVOSi2O6, goldmanite, calcium vanadic garnet, Ca3V2Si3O12 and roscoelite, vanadium mica, KV2AlSi3O10(OH)2 have been hydrothermally synthesized from chemically prepared starting materials at moderate P. T. conditions, ranging over 200°C-800°C and 15, 000-45, 000 psi for 20-96 hour.
    Equilibrium conditions of these minerals as expressed in the VO2-V3O5-V2O3 system and valency states of vanadium have been determined.
feedback
Top