Mineralogical Journal
Online ISSN : 1881-4174
Print ISSN : 0544-2540
ISSN-L : 0544-2540
Volume 17, Issue 7
Displaying 1-5 of 5 articles from this issue
 
  • Tetsuya SHOJI, Hiroko TSUKADA, Tadashi MARIKO, Hiroaki KANEDA
    1995 Volume 17 Issue 7 Pages 313-321
    Published: 1995
    Released on J-STAGE: March 31, 2007
    JOURNAL FREE ACCESS
    Electron microprobe analysis of grossular-spessartine garnets hydrothermally synthesized from glass at 300–700°C shows that the composition is continuous above 490°C. Below this temperature there is a compositional gap between 70 and 96 mol % spessartine at 480°C and between 55 and 97 mol % at 450°C. The gap extends up to 36 mol % spessartine at 400°C and up to 30 mol % at 300°C on the grossular side, but is not clear on the spessartine side because of the fO2 unbuffered experiments. Hydrothermal treatment of garnet-anorthite-tephroite mixture with bulk composition of Gr33.3 Sp66.7 shows that garnet grows above 430°C, and that no change is recognized at 400°C. These facts indicate that garnet of the grossular-spessartine series forms a complete solid solution above 490°C, and shows a certain indication that they exsolve to Ca-rich and Mn-rich garnets at lower temperatures. The additional experiments indicate that below 415°C the tie-line connecting the two garnets is replaced by the one connecting anorthite and tephroite in the system CaO–MnO–Al2O3–SiO2.
    Download PDF (649K)
  • Katsuhiro TSUKIMURA
    1995 Volume 17 Issue 7 Pages 322-329
    Published: 1995
    Released on J-STAGE: March 31, 2007
    JOURNAL FREE ACCESS
    This paper describes a new hydrothermal solution equipment that allows us to extract a solution from a reaction vessel up to 200°C. The vessel of the equipment is made of Teflon, and is capped by a titanium head accommodating Polyflon filters in the solution exit hole of the head. A quick-connect is screwed into the solution exit hole. The valve of the quick-connect opens when it connects to another quick-connect connecting to a solution-extraction tube. The solution in the vessel is extracted through the tube into a glass bottle filled with water. When the quick-connects are disconnected the valve of the quick connect closes. Because the vessel is free from the solution-extraction tube when it is in a furnace, the vessel can rotate in the furnace to mix a solid and a solution during reaction. This equipment can be used for measuring the solubility of a solid and the minor element distribution between a solid and a solution. Using this equipment, the solubilities of quartz were successfully measured at 150 and 200°C.
    Download PDF (984K)
  • Isao KUSACHI, Chiyoko HENMI, Shoichi KOBAYASHI
    1995 Volume 17 Issue 7 Pages 330-337
    Published: 1995
    Released on J-STAGE: March 31, 2007
    JOURNAL FREE ACCESS
    Frolovite was found in a vein consisting of borate minerals which developed along the boundary between crystalline limestone and skarns at Fuka, Okayama Prefecture. Frolovite occurred as aggregates of granular crystals up to 0.15 mm long and 0.05 mm wide, in association with olshanskyite and calcite. Wet analyses and EPMA gave the empirical formula C a0.998B2.008O8H7.981 on the basis of O=8, which was consistent with the formula Ca[B(OH)4]2 reported by Simonov et al. (1976). X-ray powder data for frolovite from Fuka were determined with accuracy. The reflections were indexed on the triclinic cell reported by Simonov et al. (1976). The unit cell parameters are a=7.764(4), b=5.679(4), c=8.126(5)Å, α=113.15(1), β=101.604(7) and γ=107.86(1)°. It was optically biaxial negative with refractive indices α=1.561, β=1.573, γ=1.584; VHN25 =168 kg/mm2 and a measured density of 2.22 g/cm3.
    It is likely that frolovite at Fuka was formed by an alteration of olshanskyite, where the Ca ion had been removed and water had been added at a low temperature of around 70°C.
    Download PDF (424K)
  • Satoshi MATSUBARA, Akira KATO, Fumihiko MATSUYAMA
    1995 Volume 17 Issue 7 Pages 338-345
    Published: 1995
    Released on J-STAGE: March 31, 2007
    JOURNAL FREE ACCESS
    Visibly zoned grains composed of amber yellow rim and grey black core in a lepidolite-bearing pegmatite from Myokenzan, Ibaraki Prefecture, consist of microlite plus uranmicrolite rim and of stibiotantalite core. The second and third are new to Japan. The associated minerals include lepidolite, albite, quartz and the members of manganocolumbite-manganotantalite series. Microlite is high in Na2O content, and compositionally close to the ideal formula NaCa(Ta,Nb)2O6(F, OH). Uranmicrolite is also high in Na2O and UO2 contents yielding the relation Na>U>Ca. This relation is unique to this species. Stibiotantalite is niobian with Ta : Nb = 3 : 1. The chemical compositions of manganocolumbite-manganotantalite series are around the point of Nb : Ta = 1 : 1 with minor fluctuation, requiring two names. The unit cell parameters of microlite and stibiotantalite are; a=10.440Å and a=4.930, b=11.821, c=5.548Å respectively. Uranmicrolite rims microlite and uranium-rich microlite fills cracks therein. This is interpreted as the later incorporation of uranium-bearing material and its fixation after the formation of microlite.
    Download PDF (1231K)
  • Ernest H. NICKEL
    1995 Volume 17 Issue 7 Pages 346-349
    Published: 1995
    Released on J-STAGE: March 31, 2007
    JOURNAL FREE ACCESS
    Download PDF (272K)
feedback
Top