FLUOROKINOSHITALITE AND FLUOROTETRAFERRIPHLOGOPITE : NEW SPECIES OF FLUORO-MICA FROM BAYAN OBO, INNER MONGOLIA, CHINA

• MIYAWAKI RITSURO

  Department of Geology and Paleontology, National Museum of Nature and Science

• SHIMAZAKI HIDEHIKO

  Department of Geology and Paleontology, National Museum of Nature and Science:The University of Tokyo

• SHIGEOKA MASAKO

  Department of Geology and Paleontology, National Museum of Nature and Science

• YOKOYAMA KAZUMI

  Department of Geology and Paleontology, National Museum of Nature and Science

• MATSUBARA SATOSHI

  Department of Geology and Paleontology, National Museum of Nature and Science

• YURIMOTO HISAYOSHI

  Department of Natural History Sciences, Hokkaido University

• YANG ZHUMING

  Institute of Geology and Geophysics, Chinese Academy of Sciences

• ZHANG PEISHAN

  Institute of Geology and Geophysics, Chinese Academy of Sciences

Abstract

Two new species of F-mica, fluorokinoshitalite (BaMg_3Al_2Si_2O_<10>F_2) and fluorotetraferriphlogopite (KMg_3Fe^<3+>Si_3O_<10>F_2) occur in Bayan Obo, Inner Mongolia, China. They form subhedral to euhedral platy crystals in metamorphosed carbonate rocks. They are associated with phlogopite, yangzhumingite, and rare earth minerals such as bastnasite-(Ce), cordylite-(Ce), monazite-(Ce), fluorbritholite-(Ce) and huanghoite-(Ce). Fluorokinoshitalite is transparent and colorless with white streak and pearly luster. Cleavage is perfect on {001}. The calculated density is 3.235g cm^<-3>. Fluorotetraferriphlogopite is brown in color with white to pale brown streak. It is transparent showing pearly luster and perfect cleavage on {001}. The hardness is 3-4 on the Mohs scale. The calculated density is 2.966g cm^<-3>. This mineral is optically biaxial (-) with n=1.576 (min.)-1.582 (max.). It shows reverse pleochroism (Z'=colorless, X'=light brown). Electron microprobe analyses with SIMS for Li gave empirical formulae (based on 12 anions); (Ba_<0.56>Na_<0.25>K_<0.06>)(Mg_<2.76>Fe^<2+>_<0.14>Ti_<0.01>) (Si_<2.73>Al_<1.15>Fe^<3+>_<0.12>)O_<10>[F_<1.72>(OH)_<0.28>] and (K_<0.94>Na_<0.02>Ba_<0.01>)(Mg_<2.62>Li_<0.15>Fe^<+2>_<0.14>_Mn_<0.01>)(Si_<3.33>Fe^<3+>_<0.66>Al_<0.01>)O_<10>[F_<1.65>(OH)_<0.35>] for fluorokinoshitalite and fluorotetraferriphlogopite, respectively. The lattice parameters were refined in the monoclinic system (C2/m) with the XRD data obtained with an IP-Gandolfi camera as; a=5.3161 (11), b=9.2082(15), c=10.044(2) Å, β=100.158(18)°, V=483.97(17) Å^3 (fluorokinoshitalite) and a=5.325(3), b=9.217(5), c=10.192(7) Å, β=100.03(5)°, V=492.6(5) Å^3 (fluorotetraferriphlogopite).

Journal

• Clay Science

  Clay Science 15 (1), 13-18, 2011

  The Clay Science Society of Japan

Keywords

• Fluorokinoshitalite
• Fluorotetraferriphlogopite
• New mineral
• Bayan Obo

Details

• CRID: 1390282679088450560
• NII Article ID: 110008661168
• NII Book ID: AA00607148
• DOI: 10.11362/jcssjclayscience.15.1_13
• ISSN: 21863555
• ISSN: 00098574
• Text Lang: en
• Data Source:
  • JaLC
  • CiNii Articles
• Abstract License Flag: Disallowed