Uralborite from Fuka, Okayama Prefecture, Japan.

• KUSACHI Isao

  Department of Earth Sciences, Faculty of Education, Okayama University

• SHIRAGA Kanako

  Department of Earth Sciences, Faculty of Education, Okayama University

• KOBAYASHI Shoichi

  Division of Earth Sciences, Kurashiki University of Science and the Arts

• YAMAKAWA Junji

  Department of Earth Science, Faculty of Sciences, Okayama University

• TAKECHI Yasushi

  Kurashiki Museum of Natural History

抄録

Uralborite, CaB₂O₂(OH)₄, was found in a vein consisting of borate minerals that cut into crystalline limestone at Fuka, Okayama Prefecture, Japan. It occurs as aggregates of fibrous crystals up to 0.2 mm long and as euhedral crystals up to 7 mm long and 3 mm wide, in association with sibirskite, borcarite, fluorite and calcite.<br>    Electron microprobe analyses and ICP gave the empirical formula Ca_1.006B_2.019O_2.069(OH)_3.931 on the basis of O=6. X-ray powder diffraction were indexed on the monoclinic cell, a=6.923(1), b=12.326(1), c=9.831(1)Å, β=97.09(1)°, determined by a single crystal method. The mineral was optically biaxial positive with refractive indices α=1.605(2), β=1.611(2), γ=1.618(2). The Vickers microhardness was 372 kg mm⁻² and the Moh's scale of hardness was 4.5. The density was 2.58(2) g cm⁻¹. It is likely that uralborite at Fuka was formed as a secondary mineral by a late-hydrothermal alteration of sibirskite.

収録刊行物

• Journal of Mineralogical and Petrological Sciences

  Journal of Mineralogical and Petrological Sciences 95 (4), 43-47, 2000

  一般社団法人　日本鉱物科学会

キーワード

• Geology
• Geophysics

詳細情報

• CRID: 1390001206546430976
• NII論文ID: 10011128862
• NII書誌ID: AA11460926
• DOI: 10.2465/jmps.95.43
• BIBCODE: 2005JMPeS..95...43K
• COI: 1:CAS:528:DC%2BD3cXltlKqtrg%3D
• ISSN: 13493825
• ISSN: 13456296
• ISSN: http://id.crossref.org/issn/13456296
• 本文言語コード: en
• データソース種別:
  • JaLC
  • Crossref
  • CiNii Articles
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